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The ESA has announced that Gaia’s primary mission is coming to an end. The spacecraft’s fuel is running low, and the sky-scanning phase of its mission is over. The ground-breaking mission has taken more than three trillion observations of two billion objects, mostly stars.

The ESA launched Gaia in December 2013. It’s an astrometry mission that measures the positions, motions, and distances of stars with extreme accuracy. It created the largest and most accurate 3D map of space ever, including about one billion objects, mostly stars but also quasars, comets, asteroids, and planets.

Gaia’s mission lasted twice as long as expected, and its data has changed astronomy. It serves as the foundation for many new discoveries and insights into the Milky Way. Astronomy and astrophysics would be far behind where they are now if it weren’t for Gaia. Regular Universe Today readers have encountered its data frequently.

“Today marks the end of science observations and we are celebrating this incredible mission that has exceeded all our expectations, lasting for almost twice its originally foreseen lifetime,” says ESA Director of Science Carole Mundell. “The treasure trove of data collected by Gaia has given us unique insights into the origin and evolution of our Milky Way galaxy, and has also transformed astrophysics and Solar System science in ways that we are yet to fully appreciate. Gaia built on unique European excellence in astrometry and will leave a long-lasting legacy for future generations.”

Gaia hasn’t always had it easy at its position at the Sun-Earth L2 Lagrange point, about 1.5 million kilometres from Earth. In April 2024, a tiny micrometeorite smaller than a grain of sand struck, puncturing a tiny hole in the satellite’s protective cover. The hole allowed a tiny bit of sunlight into the spacecraft, disrupting its sensors. In May 2024, a solar storm struck, and it suffered an electronics malfunction that led to an inordinately high number of false detections. In both cases, Gaia recovered and continued normal operations.

Gaia has three instruments that allow it to be so accurate. Its astrometric instrument (ASTRO) determines the positions of stars in the sky. By measuring the same stars multiple times over different years, Gaia can measure a star’s position and proper motion.

Gaia’s radial velocity spectrometer (RVS) measures the Doppler shift of a star’s absorption lines. This reveals the star’s velocity along Gaia’s line of sight.

The photometric instrument (BP/RP) provides colour information on stars, allowing astronomers to measure critical stellar characteristics like mass, chemical composition, and temperature.

These instruments have worked together to create the largest and most accurate map of the Milky Way ever.

A model image of what our home galaxy, the Milky Way, might look like face-on: as viewed from above the disc of the galaxy, with its spiral arms and bulge in full view. In the centre of the galaxy, the bulge shines as a hazy oval, emitting a faint golden gleam. Starting at the central bulge, several glistening spiral arms coil outwards, creating a perfectly circle-shaped spiral. They give the impression of someone having sprinkled pastel purple glitter on the pitch-black background in the shape of sparkling, curled-up snakes. Image Credit: ESA/Gaia/DPAC, Stefan Payne-Wardenaar

Among its other achievements, Gaia has captured pinpoint precision orbits of more than 150,000 asteroids, accurate enough to uncover possible moons. It also discovered a new type of black hole revealed only through its gravitational influence on nearby stars.

Though its science operations are at an end, it still has data to deliver.

“After 11 years in space and surviving micrometeorite impacts and solar storms along the way, Gaia has finished collecting science data. Now all eyes turn towards the preparation of the next data releases,” says Gaia Project Scientist Johannes Sahlmann.

“This is the Gaia release the community has been waiting for, and it’s exciting to think this only covers half of the collected data.”

Antonella Vallenari, Deputy Chair of DPAC, Istituto Nazionale di Astrofisica (INAF), Padua, Italy.

Gaia’s Data Release 4 (DR4) is expected in 2026. The volume and quality of data have increased with each DR. DR 4 should contain 500 terabytes of data covering the mission’s first 5.5 years, corresponding to the length of the mission’s originally foreseen duration.

“This is the Gaia release the community has been waiting for, and it’s exciting to think this only covers half of the collected data,” says Antonella Vallenari, Deputy Chair of DPAC based at the Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory of Padua, Italy. “Even though the mission has now stopped collecting data, it will be business as usual for us for many years to come as we make these incredible datasets ready for use.”

The data release will feature more binary stars and exoplanets, among other things.

The Milky Way. This image is constructed from data from the ESA’s Gaia mission, which is mapping over one billion of the galaxy’s stars. Image Credit: ESA/Gaia/DPAC

Gaia’s final data release, DR5, is a few years away. “Over the next months we will continue to downlink every last drop of data from Gaia, and at the same time the processing teams will ramp up their preparations for the fifth and final major data release at the end of this decade, covering the full 10.5 years of mission data,” says Rocio Guerra, Gaia Science Operations Team Leader based at ESA’s European Space Astronomy Centre (ESAC) near Madrid in Spain.

Though the fuel that allows it to point itself with such accuracy is almost gone, Gaia won’t meet its demise just yet. It still has enough fuel for about 15 days of operations. Instead of using its final 15 days to take more astrometric measurements, it’s going to do some technology testing.

“The Gaia spacecraft has been constructed using a wide range of technologies which have been combined to create a unique machine that operates in a very stable environment,” the ESA explains. “The spacecraft’s stability is essential for the science observations. These technology tests would have disrupted the spacecraft for an extended period and, therefore, could not be performed during the normal science observation campaign.”

These tests will teach engineers more about Gaia’s instruments and will allow engineers to study their behaviour and the behaviour of the spacecraft as a whole. The goal is to improve the calibrations for future Gaia data releases. They will also inform the design of the next mission.

“Some of the Gaia technologies have already been re-used, for example the mirror-drive electronics and cold-gas thrusters on EUCLID,” the ESA writes. Other future missions like LISA will require extreme accuracy, and the results of these tests can help them achieve that.

Once its testing is complete, Gaia will be placed in a heliocentric orbit far away from Earth’s influence. At the end of March 2025, it will be passivated to avoid any potential harm or disruption to other spacecraft.

Though the mission will end, Gaia’s data will be used for decades. So, in that sense, it will live on.

The post The Gaia Mission’s Science Operations are Over appeared first on Universe Today.

Supermassive black holes can have trillions of times more mass than the Sun, only exist in specific locations, and could number in the trillions. How can objects like that be hiding? They’re shielded from our view by thick columns of gas and dust.

However, astronomers are developing a way to find them: by looking for donuts that glow in the infrared.

It seems almost certain that large galaxies like our own Milky Way host supermassive black holes (SMBHs) in their centers. They grow through mergers with other SMBHs and through accretion. When they’re actively accreting material, they’re called Active Galactic Nuclei (AGN) and become so bright they can outshine all of the stars in their entire galaxy. The most luminous AGN are called quasars.

SMBHs, like all black holes, emit no light themselves. Instead, the light comes from the torus of swirling gas and dust that forms an accretion ring around the SMBH. The gas and dust become superheated and emit electromagnetic radiation. So far, scientists have only imaged two SMBHs, both with the Event Horizon Telescope (EHT). (To be clear, the EHT doesn’t actually “see” the SMBH. Instead, it sees the light coming from the accretion disk and the shadow the SMBH casts on the disk.)

The first ever actual image of a black hole was taken in 2019. This shows the black hole at the heart of galaxy M87. Image Credit: Event Horizon Telescope Collaboration

Even without seeing them, astronomers are pretty certain that most large galaxies host an SMBH. How? Stars near the center of galaxies move in unusual ways as if they’re under the influence of an extremely massive object. The intense radiation from AGN is also strong evidence of an SMBH. Galaxy formation and evolution models and gravitational lensing provide additional evidence.

However, astronomers still want to find more of them so they can confirm their models or adapt them to suit observational results. The problem is that many of them are hidden from view by gas and dust. If that gas and dust are thick and dense enough, they act as a veil, blocking even low-energy X-ray light. That means our view of the galaxy centre is obscured, even if it is an AGN.

Whether or not we can see the centre of a galaxy like this depends on our viewing. From a “side” view, the torus blocks it out, while from a “top” or “bottom” view, it doesn’t.

Astronomers want to understand how many SMBHs there are in the Universe, but obviously, there’s no way to find them and count them all. What they hope to do is determine the ratio between hidden and unhidden SMBHs. To do that, they need a large enough sample to extrapolate from. That way, they can get a more accurate idea of how many SMBHs there are.

A new survey using data from multiple NASA telescopes has advanced our understanding of SMBHs. The survey and its results are detailed in a paper titled “The NuSTAR Local AGN NH Distribution Survey (NuLANDS). I. Toward a Truly Representative Column Density Distribution in the Local Universe.” It’s published in The Astrophysical Journal, and the lead author is Peter G. Boorman, an astrophysicist from the Cahill Center for Astrophysics at the California Institute of Technology.

The NuLANDS aims to find the thick dust and gas that obscures AGN. Previous efforts to detect AGN have been hampered by relying on hard X-rays, the highest-energy portion of the X-ray spectrum, often defined as X-rays with energies greater than 10 kiloelectronvolts (keV). Accretion disks around SMBHs can be heated to extremely high temperatures and emit hard X-rays.

However, thick enough gas and dust can block even hard X-rays. If the column density of the gas is too high, no hard X-rays can get through. “Hard X-ray-selected samples of active galactic nuclei (AGN) provide one of the cleanest views of supermassive black hole accretion but are biased against objects obscured by Compton-thick gas column densities of NH > 1024 cm-2,” the authors write in their paper. Compton-thick means thick enough to obscure an AGN.

The thick gas and dust that block hard X-rays absorb them and then re-emit them as lower-energy infrared light. This creates a glowing torus, or donut, of gas and dust. This is where IRAS comes in.

IRAS was the Infrared Astronomical Satellite, launched in January 1983 and operated for 10 months. It performed an infrared survey of the entire sky, and it spotted the infrared emissions from the toruses around SMBHs. Critically, it spotted these toruses whether they were face-on or edge-on.

However, IRAS didn’t discriminate against infrared sources. It also spotted galaxies undergoing rapid star formation, which emit similar infrared light as AGN. In this new research, the authors used ground-based telescopes to differentiate between the two.

At that stage, the researchers had a sample of toruses around SMBHs emitting infrared light. However, they didn’t know if they were seeing them face-on or edge-on. Remember, their goal was to determine how many SMBHs are hidden and how many aren’t. With a large enough sample containing good data, they could extrapolate how many SMBHs there are and whether all large galaxies have one.

This is where another NASA satellite comes in. NuSTAR is an X-ray space telescope that was launched in June 2012 and is still operating. One of its primary goals was to detect SMBHs one billion times more massive than the Sun.

An artist’s illustration of NASA’s NuSTAR X-ray satellite. Image Credit: NASA/JPL-Caltech

NuSTAR can detect high-energy X-rays that pass through thick dust and gas, so it can detect edge-on SMBHs. However, it can use hours of observation time to detect these X-rays, so for it to be effective, it has to know where to look first. That’s what IRAS helped with.

“It amazes me how useful IRAS and NuSTAR were for this project, especially despite IRAS being operational over 40 years ago,” said lead author Boorman. “I think it shows the legacy value of telescope archives and the benefit of using multiple instruments and wavelengths of light together.”

In their NuLANDS survey, the researchers looked at 122 nearby AGN chosen for their warm infrared colours. “To tackle this issue, we present the NuSTAR Local AGN NH Distribution Survey (NuLANDS)—a legacy sample of 122 nearby (z < 0.044) AGN primarily selected to have warm infrared colors from IRAS between 25 and 60 ?m,” the authors write.

Their sample of galaxies is also biased towards those whose AGN is obscured by something close to them rather than by some large-scale feature of the galaxy itself. “By construction, our sample will miss sources affected by severe narrow-line reddening, and thus segregates sources dominated by small-scale nuclear obscuration from large-scale host-galaxy obscuration,” the authors explain.

The researchers found that 35% ± 9% of galaxies have Compton-thick dust, meaning their AGN and SMBH are obscured. So, about one-third of the Universe’s SMBHs are obscured. However, these are only the first results from NuLANDS, and while 122 AGN is a sizeable survey, there’s more to come.

These results support some of the thinking around SMBHs, their masses, and their numbers. SMBHs must consume an enormous amount of material to reach their enormous sizes. That means many of them should be obscured by the very dust they’ll eventually consume. Boorman and his co-authors say their results support this idea.

“If we didn’t have black holes, galaxies would be much larger,” said study co-author Poshak Gandhi, a professor of astrophysics at the University of Southampton in the UK. That’s for two reasons. First, they consume material that would otherwise form more stars. Second, sometimes too much material falls toward the black hole, and they belch up the excess. That ejected material can disperse the clouds of gas where stars form, slowing the galaxy’s star formation.

“So if we didn’t have a supermassive black hole in our Milky Way galaxy, there might be many more stars in the sky. That’s just one example of how black holes can influence a galaxy’s evolution,” said Gandhi.

The post About a Third of Supermassive Black Holes are Hiding appeared first on Universe Today.

Water is the essence of life. Every living thing on Earth contains water within it. The Earth is rich with life because it is rich with water. This fundamental connection between water and life is partly due to water’s extraordinary properties, but part of it is due to the fact that water is one of the most abundant molecules in the Universe. Made from one part oxygen and two parts hydrogen, its structure is simple and strong. The hydrogen comes from the primordial fire of the Big Bang and is by far the most common element. Oxygen is created in the cores of large stars, along with carbon and nitrogen, as part of the CNO fusion cycle.

Because of its origin, we’ve generally thought that oxygen (and correspondingly water) grew in abundance over time. From the first stars to the present day, each generation cast oxygen into space in its dying moments. So, while water was rare in the early Universe, it is relatively common now. But a new study suggests that isn’t the case.

Astronomers categorize stars into populations depending on their age and metallicity, where “metals” are any elements other than hydrogen and helium. The youngest and most metal-rich stars, such as the Sun, are called Population I. Older stars with fewer metals are Population II. The oldest stars, the very first stars to appear in the Universe, are known as Population III. Though we haven’t observed Pop III stars directly, they would have been enormous stars made entirely of hydrogen and helium. The first seeds of everything we see around us, from oceans to trees to beloved friends, formed within these first stars. A new study on the arXiv argues that Pop III stars also flooded the cosmos with water.

In their study, the team modeled the explosions of small (13 solar mass) and large (200 solar mass) early stars. The large stars would have been the very first stars formed from primordial clouds, while the smaller stars would have been the first stars to form in early stellar nurseries. Not quite Pop III stars, but with very low metallicity. When the smaller stars died, they exploded as typical supernovae, but when the large stars died, they exploded as brilliant pair-instability supernovae.

Based on simulations, these stars would have greatly enriched the environment with water. The molecular clouds formed from the remnants of these stars had 10 to 30 times the water fraction of diffuse molecular clouds seen in the Milky Way today. Based on this, the team argues that by 100 to 200 million years after the Big Bang, there was enough water and other elements in molecular clouds for life to form.

Whether life actually did appear in the Universe so early is an unanswered question. There is also the fact that while water formed early, ionization and other astrophysical processes may have broken up many of these molecules. Water might have been plentiful early on, but the Universe entered a dry period before Pop II and Pop I stars generated the water levels we see today. But it’s possible that much of the water around us came from the very first stars.

Reference: Whalen, Daniel J., Muhammad A. Latif, and Christopher Jessop. “Abundant Water from Early Supernovae at Cosmic Dawn.” arXiv preprint arXiv:2501.02051 (2025).

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There’s plenty of action at the center of the galaxy, where a supermassive black hole (SMBH) known as Sagittarius A* (Sgr A*) literally holds the galaxy together. Part of that action is the creation of gigantic flares from Sgr A*, which can give off energy equivalent to 10 times the Sun’s annual energy output. However, scientists have been missing a key feature of these flares for decades – what they look like in the mid-infrared range. But now, a team led by researchers at Harvard’s Center for Astrophysics and the Max Planck Institute for Radio Astronomy has published a paper that details what a flare looks like in those frequencies for the first time.

Astronomers have been observing Sgr A* since the 1990s and have known about the flares, which were initially seen as variances in the SMBH’s brightness. It has been observed with all manner of telescopes, including the Chandra X-ray observatory and, perhaps most famously, the Event Horizon Telescope, which was responsible for the famous first image of M87*, another black hole at the center of the Messier galaxy. EHT also released an image from Sgr A* itself in May of 2022.

So far, those observations have been in visible light through infrared and from far infrared up through X-rays. There has always been a gap in the middle of the infrared range. Several factors explain this gap.

Fraser talks about imaging Sgr A*

First, Sgr A* is relatively weak in the mid-infrared range compared to other ranges, so it doesn’t stand out as much against the background noise of the universe. Second, much of the mid-infrared emissions get obscured by the dust cloud surrounding the SMBH at the galaxy’s center, blocking it from detectors at Earth 28,000 light years away. Third, there were technological limitations to infrared sensors themselves. There were ground-based telescopes that could have detected the signal, but the Earth’s atmosphere blocked even more of it.

That required scientists to wait for the long-delayed James Webb Space Telescope (JWST). When it finally launched in late 2021, it was only a matter of time before they would get observational time to watch Sgr A* and hopefully observe a flare with the most powerful infrared detector ever launched into orbit. 

JWST did indeed get observational time with Sgr A* and saw a flare, representing the first-ever recording of a flare in the mid-infrared range. But the research team didn’t stop there – they were also watching with several other telescopes for confirmation of the JWST signal.

Fraser talks about other features of Sgr A*

They didn’t find any in the X-ray range with Chandra, though that was probably because the flare wasn’t strong enough to emit a significant amount of X-rays. But they did see a signal from the Sub-Millimeter Array (SMA) in Hawai’i, which detected radio waves following along about 10 minutes behind the detected mid-infrared signal.

That confirmation was necessary because it allowed the experimentalists to provide even more insight about the same flare to the theoreticians. Their job is then to confirm the models and simulations of what causes the flares in the first place. The current theory is that they occur when magnetic field lines in the SMBH’s accretion disk join up and emit massive amounts of radiation in a process known as synchrotron emission. In synchrotron emission, a bunch of charged particles – typically electrons – get pushed down the magnetic field lines like they were part of a massive particle accelerator.

The data from JWST fits nicely into that theory. However, there appear to be additional unanswered questions about whether that feature was specific to Sgr A* or whether it could be observed for other SMBHs such as M87*. For now, that remains to be seen, though given the interest in this particular black hole in this specific wavelength, while this might have been the first study published on the topic, it probably won’t be the last.

Learn More:
CfA – Scientists Make First-Ever Detection of Mid-IR Flares in Sgr A*
von Fellenberg et al – First mid-infrared detection and modeling of a flare from Sgr A*
UT – Echoes of Flares from the Milky Way’s Supermassive Black Hole
UT – A Black Hole Emitted a Flare Away From us, but its Intense Gravity Redirected the Blast Back in our Direction

Lead Image:
This artist’s conception of the mid-IR flare in Sgr A* captures the variability, or changing intensity, of the flare as the black hole’s magnetic field lines approach each other. The byproduct of this magnetic reconnection is synchrotron emission. The emission seen in the flare intensifies as energized electrons travel along the SMBH’s magnetic field lines at close to the speed of light. The labels mark how the flare’s spectral index changes from the beginning to the end of the flare.
Credit: CfA/Mel Weiss

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A tiny asteroid loitering in a near-Earth orbit for a few months last year may have an intriguing origin on our Moon. Its characteristics led scientists to ask: is it a chip off the old lunar block, making a pass by Earth for a visit?

The object is known as Near-Earth Asteroid (NEA) 2024 PT5 (or PT5, for short) and its orbit is very similar to Earth’s. Oddly enough, that region often gets littered with rocket bodies. Interestingly, it’s also a region where debris blasted off the Moon during impacts tends to collect. So, could PT5 have come from the Moon? There’s a good chance that it did but how do we know this?

An artist’s impression of a lunar explosion, caused by the impact of a meteorite on the surface of the Moon. Such an impact could have created asteroid PT5. Credit: NASA/Jennifer Harbaugh

Planetary scientists have long studied Near-Earth objects (NEOs) and NEAs to understand their origins. One way to do that is to determine a relationship between their current orbits, properties, and sources, One such origin is the Main Asteroid Belt, but it’s not the only place where asteroids emerge. Each object is a special case, and scientists compare them with known meteorites. Of course, you need some data about the object’s physical characteristics—including its reflectance and albedo. Those two properties can often tell you what part of an asteroid population the object came from. They’re particularly important if there are no physical samples available for analysis.

Looking at Spectra of the Suspected Moon Chunk

A team of observers used the Lowell Discovery Telescope in Flagstaff, Arizona, to take reflectance spectra of PT5. This 10-meter-wide chunk of space rock was first discovered in August of 2024 by a survey project in South Africa. Its orbit made it a perfect target for another survey called MANOS (Mission Accessible Near-Earth Object Survey). The Lowell observations took place a week later to determine reflectance properties. Those are useful to figure out its origin—either natural or artificial. Subsequent observations of the object characterized its rotation and revealed it has a rocky, silicate-rich composition. That ruled out an artificial origin.

The reflectance spectrum from the Lowell telescope does give a match to known lunar samples. PT5 does not match any known asteroid types, however. For example, it looks to be pyroxene-rich, which indicates the rock came from an igneous or possibly metamorphic environment. Other asteroids aren’t the same—they tend to be richer in olivine. Based on that data and its tumbling motion, scientists conclude that it is ejecta from an impact on the Moon. If that’s the case, it’s only the second time a NEA has been found that came from the Moon.

Reflectance data from a MANOS survey of NEA 2024 PT5 made on January 7, 2025. Courtesy MANOS/Lowell Observatory.

If only one existed, we could say it’s a space oddity. However, the presence of two such objects changes the story. It also suggests that there’s a whole population out there waiting to be observed.

What PT5 Means

So, let’s say there is this collection of lunar chunks floating around out there. They can give insight into how impacts affect the Moon or other bodies such as Earth and Mars. They would also help identify the sources of other asteroids and meteorites from this under-studied population of near-Earth objects. In a paper discussing PT5, authors Theodore Kareta of Lowell Observatory, Oscar Fuentes-Munoz from NASA JPL, and others, describe their study of this rock, its orbit, and physical characteristics. They write, “If there really is a population of Moon Rocks out there waiting to be discovered on near-Earth orbits, they almost certainly are rare members of the NEO population.”

There may well be only about 16 currently known NEOs that could have come from the Moon, but there could be more. Now, the challenge is to separate them from the general population of near-Earth objects and subject them to further study. Since the orbits of lunar ejecta pieces tend to evolve into Aten- or Apollo-type orbits, the authors point out there could be between 5 and 10 times more of these lunar chips off the old block in the neighborhood. (Aten asteroids are a group known as “Earth-crossing” asteroids because their orbits cross our planet’s orbit. Apollo asteroids also follow orbits that cross ours.)

Three classes of asteroids that pass near Earth or cross its orbit are Apollo, Aten and Amor. Apollo asteroids like 2014 SC324 routinely cross Earth’s orbit, Atens also cross but have different orbital characteristics and Amors cross Mars’ orbit but miss Earth’s. Credit: ESA Future Observations of Suspected Moon Pieces

If there is a larger population of lunar-sourced asteroids in near-Earth-type orbits, then the next step is to figure out ways to find them. Certainly, asteroid surveys will help, along with further observations of their reflectance and charts of their orbits. Since these asteroids are generally thought to be relatively small, it will take a new generation of larger telescopes and observational techniques to find them.

Probably one of the greatest results of the search for these objects is what they can tell us about impact histories in the inner solar systems. The paper’s authors point this out. “First at Mars and now at the Earth, the impact histories of the terrestrial planets appear to be partially encoded in the asteroids that orbit nearby to them. Future work to discover more of and measure the properties of this population of near-Earth objects which are sourced by the Moon will be critical to link asteroid and lunar science in the era of Artemis and the Vera Rubin Observatory’s LSST.”

The next chance to observe PT5 is coming up this month when it lingers near Earth again. NASA has plans to track it with radar and undoubtedly others will be studying it to understand more about this “mini-Moon”.

For More Information

On The Lunar Origin of Near-Earth Asteroid 2024 PT5
NASA to Track Asteroid 2024 PT5 on Next Close Pass, January 2025

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A fuzzy form of dark matter may clump up to become the cores of galaxies, according to new research.

The traditional dark matter hypothesis, that it’s some form of cold, massive particle that hardly ever interacts with itself or with normal matter, has some difficulties. In particular, it can’t quite explain the dense cores of galaxies. Cold, heavy dark matter tends to produce extremely dense cores, far denser than what we observe.

But dark matter might be something else. Recently astronomers have hypothesized that dark matter might instead be incredibly light, far lighter than any known particle. This “fuzzy” dark matter would allow the quantum wave nature of the particles to manifest on macroscopic – even galactic – scales, allowing them to form large, diffuse clumps known as “dark stars.”

Dark stars can be incredibly huge, stretching for thousands of light-years, while still having relatively low density. This would match observations of galaxy cores, which makes this an intriguing hypothesis to follow.

In a recent letter appearing in the preprint server arXiv in December, an international collaboration of astrophysicists explored how galaxies might evolve in response to fuzzy dark matter. For this first step, they did not attempt to fully recreate an entire complex galaxy. Instead they built a simple toy model containing only two components: a large fraction of fuzzy dark matter and a smaller fraction of a simple, ideal gas.

They then simulated how these two components would interact with each other and evolve. They found that no matter how they start off, normal matter and fuzzy dark matter quickly find an equilibrium, with the two kinds of matter mixing together to make a large, stable core, surrounded by a cloud of dark matter.

The researchers pointed out that this would serve as the ideal representation of a galactic core, which contains higher – but not too high – densities of normal matter. This is the first step to confirming a key prediction of the fuzzy dark matter model. However, there is still a lot of work to be done. The next step is to build even more realistic simulations of the growth and evolution of galaxies, tracking how fuzzy dark matter, and the dark stars they create, influences their local environments. Then we can take those results and compare to observations to see if this idea is worth investigating even more.

The post Galaxy Cores May be Giant Fuzzy Dark Stars appeared first on Universe Today.

After the Big Bang came the Dark Ages, a period lasting hundreds of millions of years when the universe was largely without light. It ended in the epoch of reionization when neutral hydrogen atoms became charged for the first time and the first generation of stars started to form. The question that has perplexed astronomers is what caused the first hydrogen atoms to charge. A team of researchers have observed an early quasar that pumped out enormous amounts of x-ray radiation helping to drive the reionization. 

The universe began with the Big Bang around 13.8 billion years ago, starting as a hot, dense point that was infinitely small. In the first few minutes, light elements like hydrogen and helium formed, and a few hundred million years later – possibly as early as 380,000 years, the Cosmic Microwave Background (CMB) marked the end of the Dark Ages. Gravity then pulled matter together, forming the first stars and galaxies during the Epoch of Reionization. These early stars ionized hydrogen, making the universe transparent. Over billions of years, galaxies merged and structures formed, with our solar system emerging around 4.6 billion years ago. 

The full-sky image of the temperature fluctuations (shown as color differences) in the cosmic microwave background, made from nine years of WMAP observations. These are the seeds of galaxies, from a time when the universe was under 400,000 years old. Credit: NASA/WMAP

The transition between the Dark Age and the Reionization phase has been the subject of study by a team of astronomers from Yale University. They have detected intense periods of brightening and dimming of a quasar about 12 billion light years away. The observation sheds some light on the accelerated rate of growth experienced by some objects in the early universe.

The quasar identified by the team goes by the catchy title J1429+5447. It’s found in the constellation of Lyra and is so far away that its light takes 12 billion years to reach us, this means we see it now as it was just 1.6 billion years after the Big Bang. Studying it gives us a real insight into the early evolution of the universe. At its centre is a supermassive black hole which accretes matter and in the process emits intense amounts of radiation across the whole electromagnetic spectrum. The team announced their discovery on 14 January at a meeting of the American Astronomical Society. 

Artist’s impression of a quasar core. Quasars are powered by interactions between supermassive black holes and their accretion disks at the hearts of galaxies. JWST observed one in infrared light to reveal its feeding mechanism. Courtesy T. Mueller/MPIA.

Using NuSTAR, an X-ray space telescope to study the quasar they compared their observations with previous studies 4 months earlier using the Chandra X-ray telescope. To their surprise, in just 4 months, the X-ray emissions from the quasar doubled! 

The spectral ranges of the XMM-Newton and NuSTAR Telescopes. (Credits: NASA, ESA)

Meg Urry, Professor of Physics and Astronomy and co-author explained ‘The level fo X-ray variability in terms of intensity and rapidity is extreme.  It is almost certainly explained by a jet pointing toward — a cone in which particles are transported up to a million light years away from the central, supermassive black hole. Because the jet moves at nearly the speed of light, effects of Einstein’s theory of special relativity speed up and amplify the variability.”

The team believe these early quasars like J1429+5447 provided the energy to end the Dark Ages and herald in the Reionisation period. Their study has revealed how crucial quasars were to the early evolution of the universe.

Source : This quasar may have helped turn the lights on for the universe

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When a new space telescope is launched, it’s designed to address specific issues in astronomy and provide critical answers to important questions. The JWST was built with four overarching science goals in mind. However, when anticipating new telescopes, astronomers are quick to point out that they’re also excited by the unexpected discoveries that new telescopes make.

There has been no shortage of unexpected discoveries regarding the JWST, especially regarding the very early Universe.

In December 2022, after the JWST had been performing science operations for just six months, the telescope revealed the presence of small red objects in the high-redshift sky. Astronomers called them Little Red Dots (LRDs). The nature of these objects wasn’t obvious, but they’re abundant, and astronomers are curious about what they can tell us about the early Universe.

Recently, a team of researchers compiled a large sample of these LRDs. Most of them existed only 1.5 billion years after the Big Bang. According to observations, a large number of the LRDs may contain growing supermassive black holes (SMBHs). There is no class of corresponding objects at lower redshifts, which only deepens their mysterious nature.

The new research is “The Rise of Faint, Red AGN at z>4: A Sample of Little Red Dots in the JWST Extragalactic Legacy Fields.” It’s been accepted for publication in The Astrophysical Journal, and the lead author is Dale Kocevski of Colby College in Waterville, Maine. The paper is available on the pre-print server arxiv.org.

“We’re confounded by this new population of objects that Webb has found. We don’t see analogs of them at lower redshifts, which is why we haven’t seen them prior to Webb,” said lead author Kocevski. “There’s a substantial amount of work being done to try to determine the nature of these little red dots and whether their light is dominated by accreting black holes.”

The JWST has generated an enormous amount of data during its observations. The astronomers behind the sample of LRDs used publicly available data from the CEERS, PRIMER, JADES, UNCOVER and NGDEEP surveys. While they’re not the first to probe datasets for LRDs, the team used a different methodology that identified LRDs over a wider redshift range. They identified 341 LRDs spanning from about redshift 2 to 11. The researchers found that LRDs emerged in large numbers only 600 million years after the Big Bang, before their number rapidly around 1.5 billion years after the Big Bang.

These images from the research show a subset of the 341 Little Red Dots from the various surveys. Image Credit: Kocevski et al. 2024.

Fortunately, some spectroscopic data are already available for a portion of the LRDs in the Red Unknowns: Bright Infrared Extragalactic Survey (RUBIES), which contains JWST/NIRSpec spectroscopy of red sources. The spectroscopic data showed that about 70% of the LRDs show evidence of rapidly rotating gas. The gas is moving at about 1,000 km per second, indicating that these could be accretion disks around supermassive black holes.

The conclusion seems pretty clear: LRDs are active galactic nuclei (AGN), which are black holes that are actively feeding. But why do they peter out after about 1.5 billion years after the Big Bang?

“The most exciting thing for me is the redshift distributions. These really red, high-redshift sources basically stop existing at a certain point after the big bang,” said Steven Finkelstein, a co-author of the study at the University of Texas at Austin. “If they are growing black holes, and we think at least 70 percent of them are, this hints at an era of obscured black hole growth in the early universe.”

Most of us remember when some overeager headlines claimed that the JWST had “broken cosmology.” The discovery of LRDs was responsible for some of this thinking. If the light coming from the LRDs was from stars, then some galaxies had to have grown very large very fast. Our theories couldn’t account for them.

If these results are true, then the light is coming from active galactic nuclei rather than large, rapidly growing galaxies. In this case, our theories are safe (for now).

“This is how you solve the universe-breaking problem,” said Anthony Taylor, a co-author of the study at the University of Texas at Austin.

In their paper, the authors highlight some of their important points.

“One of our primary findings is that the red compact objects that have come to be known as little red dots appear in large numbers at z > 4,” they write. “The redshift distribution that we observe for our sample of LRDs may provide insight into the nature of their obscuration and the mechanisms fueling their nuclear activity.”

This figure shows the redshift distribution of the final sample of LRDs in the research. Image Credit: Kocevski et al. 2024.

Their obscuration could result from what’s called “inside-out growth.” In that model, stars begin forming in a galaxy’s central regions first, and they are created more rapidly in those regions. Eventually, star birth moves outward to a galaxy’s periphery. This is because gas collapses inward due to gravity, fuelling star birth in the center. That same collapsing gas could also trigger the concurrent growth of the galaxy’s SMBH. This can also explain the red colour we see. “The rapid accumulation of metals in the proto-bulge then provides the reddening we observe,” the authors write.

As star birth moves outward, less dust is deposited near the AGN, meaning that over time, there are fewer LRDs.

However, inside-out growth is only one potential explanation for LRDs, though it’s a good fit with much of the existing data. The team intends to follow up on this work with mid-infrared imaging and spectroscopy. That will help them understand the number density of these faint AGN and shed more light on what’s obscuring them.

“There’s always two or more potential ways to explain the confounding properties of little red dots,” said Kocevski. “It’s a continuous exchange between models and observations, finding a balance between what aligns well between the two and what conflicts.”

Whatever exactly is going on with LRDs, the issue shows how powerful unexpected discoveries can be. It also shows, again, how valuable the JWST is.

“While much remains to be determined about the nature of LRDs, the prevalence of broad emission lines in their spectra suggests this population is shedding light on a phase of obscured black hole growth in the early universe that was largely undetected prior to the JWST era,” the authors conclude.

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I’ve lost count of the number of times I have seen the Ring Nebula. It’s a favourite amongst stargazers around the globe and is surely one of the most well known objects in the night sky. The remains of a Sun-like star, its outer layers have drifted out into space leaving behind a the stellar corpse, a white dwarf. It looks like a giant smoke ring in the sky but what is its true shape? A team of astronomers have mapped carbon monoxide that surrounds the nebula and built a 3D model to reveal its shape. 

The Ring Nebula is a wonderful example of a planetary nebula. It’s located in the constellation Lyra, about 2,000 light-years from Earth and its progenitor star shed its outer layers 6,000 years ago leaving behind the core to become a hot white dwarf. Intense ultraviolet radiation from the white dwarf excites the surrounding gas, causing it to emit green and blue light due to ionized oxygen and nitrogen. It was discovered by Charles Messier who was hunting for comets and, as he spotted objects which clearly weren’t comets he cataloged them. The Ring Nebula is the 57th object in his catalogue so it has the designation M57.

JWST/NIRcam composite image of the Ring Nebula. The images clearly show the main ring, surrounded by a faint halo and with many delicate structures. The interior of the ring is filled with hot gas. The star which ejected all this material is visible at the very center. Courtesy JWST/University of Manchester.

A team of astronomers led by Chester F. Carlson from the Rochester Institute of Technology and Professor Joel Kastner from the Centre for Imaging Science and School of Physics and Astronomy have been exploring the shape of M57. They used the Submillimeter Array (SMA) to map the emission of carbon monoxide gas in the nebula. The carbon monoxide surrounds the hot gas and dust that appears in classic images we are all familiar with seeing. 

The Submillimeter Array (SMA) is a radio telescope located on top of Mauna Kea in Hawaii and was designed to observe the universe at submillimeter wavelengths. It is made up of eight 6-meter radio dishes arranged as an interferometer. It enables astronomers to capture high-resolution images of distant objects such as star-forming regions, galaxies, and molecular clouds by detecting the emission of faint submillimeter radiation.

This image shows two of the Atacama Large Millimeter/submillimeter Array (ALMA) 12-metre antennas. ALMA has 66 antennas that work together as an interferometer. (Credit : Iztok Bonina/ESO)

For decades, since the nebula was first photographed in 1886, astronomers have been wondering just what shape the nebula was. A dust ring shape or something resembling a soap bubble structure were the favourite models but the results from SMA observations reveal an ellipsoid structure. The team were able to draw this conclusion from analysing the velocity and location of carbon monoxide molecules from the SMA data. They would have been ejected by the star in its death-throws to reveal its shape to us today. 

The findings are similar reminiscent of observations of the Southern Ring Nebula in the constellation Vela. It was one of the first objects observed by the JWST and the results revealed more about its structure just like its more familiar northern counterpart. One slight difference is that the team observing M57 didn’t expect that the SMA data would also reveal the influence of a companion star to the progenitor red giant. They found high velocity concentrations of gas that were ejected out each end of the ellipsoidal nebula. 

Source : RIT professor leads research showing true structure of the iconic Ring Nebula

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Climate scientists must fear sounding like a broken record when discussing new record temperatures yearly. But once again, last year was the hottest one ever recorded, according to a new study by NASA scientists.

Anyone paying close attention to climate news would not be surprised. From June 2023 through August 2024, every consecutive month broke a new monthly temperature record. That is 15 straight months of consistently high temperatures. 

Such a streak directly translates into the year’s overall temperature, but just how bad was it? The Paris Agreement on climate change, signed by 195 countries and the European Union, attempts to limit the global rise in temperatures to 1.5? over a baseline temperature from the middle of last century (1951-1980). 2024 was already 1.28? above it. 

That’s not a great start, but the data gets even more dire for the climate-conscious. Temperatures in 2024 were already 1.47? above a baseline of temperatures from 1850-1900, a time before the industrial revolution, or automobile transportation, had taken off. Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, says, “That’s halfway to Pliocene-level warmth in just 150 years.”, referring to a geological period where a baseline temperature of just 1.5? above the Earth’s 2024 average resulted in sea levels that were tens of meters higher than total.

Such a sea level rise would devastate population centers home to literally billions of people and have such a dramatic effect on sea and wildlife that it’d be hard to predict the consequences. But it’s not like any of this information is new—it’s just worth reinforcing.

Even with reinforcement, more action is needed to solve the problem. The last ten years have been the warmest on record. While there is some variability between years, the trend in warming temperatures is obvious. Despite that, in 2022 and 2023, there were record releases of carbon dioxide from fossil fuels.

Even 12 years ago, Fraser and Pamela were discussing climate change and what it meant for the planet.

Additional effects could have impacted such a hot year in 2024. A NASA press release mentions everything from El Niño to volcanoes in Tonga to improved sulfur dioxide emissions from cargo ships. All undoubtedly impact the climate, but the contribution of each is difficult to tease out.

NASA’s global temperature assessment is based on data from thousands of weather stations scattered throughout the globe, both on land and sea. The same data was analyzed by other organizations, such as the US’s National Oceanic and Atmospheric Administration, Berkeley Earth, the Hadley Centre, and Copernicus Climate Services. Each used slightly different methodologies and models to determine the Earth’s temperature last year. Still, each showed a trend toward hotter temperatures – which most scientists take as unambiguous proof that the planet is getting hotter.

However, many naysayers still can’t see the forest for the trees, as a nasty cold snap could convince them of the illusion of “global warming” in general. However, the world’s overall temperature shift is getting drastic enough that local areas are literally starting to feel the heat. Schmidt said, “When changes happen in the climate, you see it first in the global mean, then you see it at the continental scale, and then at the regional scale. Now we’re seeing it at the local level.”

The fires currently threatening NASA’s Jet Propulsion Laboratory in Pasadena are just one symptom of the ongoing environmental challenges facing the world. This NASA report is just the most recent in a long line of reports that all point to the same conclusion—the world is getting warmer, and we humans are likely the ones causing it. 

Learn More:
NASA – Temperatures Rising: NASA Confirms 2024 Warmest Year on Record
UT – NASA Confirms that 2023 was the Hottest Year on Record
UT – NASA Confirms That 2023 was the Hottest Summer on Record
UT – Global Temperatures Continue to Rise

Lead Image:
This map of Earth in 2024 shows global surface temperature anomalies, or how much warmer or cooler each region of the planet was compared to the average from 1951 to 1980. Normal temperatures are shown in white, higher-than-normal temperatures in red and orange, and lower-than-normal temperatures in blue. An animated version of this map shows global temperature anomalies changing over time, dating back to 1880. Download this visualization from NASA Goddard’s Scientific Visualization Studio: https://svs.gsfc.nasa.gov/5450.
Credit: NASA’s Scientific Visualization Studio

The post It’s Official, 2024 Was the Hottest Year on Record appeared first on Universe Today.

Carbon-rich cosmic dust comes from different sources and spreads out into space, where it’s necessary for life and for the formation of rocky planets like ours. When astronomers aim their telescopes at objects in the sky, they often have to contend with this cosmic dust that obscures their targets and confounds their observations.

One reason the JWST was built is to see through some of this dust with its infrared vision and unlock new insights into astrophysical processes. In new work, the JWST was tasked with observing the dust itself.

The Wolf–Rayet binary WR 140 is about 5,000 light-years away in the constellation Cygnus. In 2022, researchers published results in Nature Astronomy revealing details about the binary star. The results showed that the stellar winds from both stars regularly collide, producing rings of carbon-rich dust that expand outward from the stars.

“We are used to thinking about events in space taking place slowly, over millions or billions of years. In this system, the observatory is showing that the dust shells are expanding from one year to the next.”

Jennifer Hoffman, co-author, University of Denver

“Massive colliding-wind binaries that host a Wolf–Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium,” the authors wrote, noting that the dust’s chemical composition and how it survives are still not understood. “The carbon-rich Wolf–Rayet binary WR 140 presents an ideal astrophysical laboratory for investigating these questions, given its well-defined orbital period and predictable dust-formation episodes every 7.93?years around periastron passage,” the authors explained in their research.

The environment near these stars when they’re close to one another is chaotic, even hostile. The winds from these evolved stars are chemically rich, and when the stronger wind from the WR star collides with the wind from the OB star, the gas is compressed, and dust is produced. Since the dust is only produced at periastron, the dust forms discrete rings. “Galactic colliding-wind WC (Wolf-Rayet stars of the carbon sequence) binaries with resolvable circumstellar dust nebulae, therefore, provide important laboratories to study this dust-formation process, where observations over the past few decades have demonstrated how dust formation is regulated by the orbit of the binary system,” the authors of the 2022 paper explain.

The pair of massive stars, one a Wolf-Rayet and one an OB star, orbit one another and reach periastron every 7.93 years. That’s when the powerful stellar winds from both stars collide. Astronomers think that evolved Wolf-Rayet stars and their colliding winds might be responsible for some of the first carbonaceous dust grains and organic material in the Universe.

The JWST captured the original 2022 images about 5.5 years after the last periastron in 2016. Now, about 14 months after the JWST’s initial look at WR 140, the space telescope has taken another long look at the interacting binary and its concentric rings of expanding carbon-rich dust. The images show how much the rings have expanded in less than two years time.

“The telescope confirmed that these dust shells are real, and its data also showed that the dust shells are moving outward at consistent velocities, revealing visible changes over incredibly short periods of time,” said Emma Lieb, the lead author of the new paper and a doctoral student at the University of Denver in Colorado.

Compare the two mid-infrared images taken by the James Webb Space Telescope of Wolf-Rayet 140, a system of dust shells ejected by two massive stars that are in an elongated orbit. In the top right of the first two images, two triangles are matched up to show how much the rings have moved in 14 months. The dust is moving away from the stars at more than 2,600 km per second, about 1% of the speed of light. The rings of carbon-rich dust are created for a few months every eight years. Image Credit: NASA, ESA, CSA, STScI, E. Lieb (University of Denver), R. Lau (NSF NOIRLab), J. Hoffman (University of Denver)

It’s relatively rare to see astronomical objects exhibit change on short timescales like this. For only 14 months, every eight years, the stellar winds collide and produce the visible carbon-rich dust rings. While WR binaries are known to produce carbon-rich dust, most pairs aren’t this active and their periastrons are much further apart in time.

“We are used to thinking about events in space taking place slowly, over millions or billions of years,” added Jennifer Hoffman, a co-author and a professor at the University of Denver. “In this system, the observatory is showing that the dust shells are expanding from one year to the next.”

“Seeing the real-time movement of these shells between Webb’s observations that were taken only 13 months apart is truly remarkable,” said Olivia Jones, a co-author at the UK Astronomy Technology Centre, Edinburgh. “These new results are giving us a first glimpse of the potential role of such massive binaries as factories of dust in the Universe.”

Astronomers have spotted other WC stars producing dust rings. However, WR 140 exceeds them all. “The extent of these distant circumstellar shells detected around WR 140 exceeds that of all other known dust-forming WC systems by factors of 4 or greater,” the authors of the 2022 paper explain.

The stars follow wide, elongated orbits, and when their winds collide every eight years, they produce carbon-rich dust for several months. The JWST’s powerful MIRI imaged dust rings that date back more than 130 years. Shells older than that have dissipated into interstellar space and are no longer coherent and visible. Some of that material may have already been taken up in star formation.

Thanks to MIRI, the researchers learned that WR 140 will likely generate tens of thousands of dust shells over hundreds of thousands of years.

“Mid-infrared observations are absolutely crucial for this analysis, since the dust in this system is fairly cool. Near-infrared and visible-light observations would only show the shells that are closest to the star,” explained Ryan Lau, a co-author and astronomer at NSF NOIRLab in Tucson, Arizona. Lau led the initial research on this system in 2022. “With these incredible new details, the telescope is also allowing us to study exactly when the stars are forming dust — almost to the day.”

These JWST images don’t show it, but not all of the dust is in the form of rings. Some of it is in clouds larger than our entire Solar System. Some of it floats freely as individual dust particles, each one only one-hundredth the width of a human hair. In all cases, the dust is carbon-rich and moving at the same speed.

One estimate says that the rings are about 1.4 trillion km apart. For comparison, if our Sun were creating these shells, one shell would be about five percent of the distance to Alpha Centauri, our nearest neighbour, before the next shell was created.

Eventually, the creation of carbon-rich dust shells will cease. Most WR stars end their lives as supernovae, with some possibly collapsing directly into black holes.

But that’s in the distant future. In humanity’s direct future, WR 140 will keep producing these carbon-rich dust shells, and the JWST will keep watching this natural laboratory to see how it all happens.

The post The Webb Shows Us Where Cosmic Dust Comes From appeared first on Universe Today.

Jupiter’s clouds aren’t what we thought they were. Planetary atmosphere experts have studied them for many years, uncovering new and puzzling mysteries. Recently, several researchers banded together to solve a long-standing mystery about those clouds. It turns out they aren’t made of ammonia ice, which is what everyone has thought for years. Instead, they seem to be largely a mix of smog and ammonium hydrosulfide. That compound forms in the atmosphere as hydrogen sulfide gas passes through ammonia.

Most of us are familiar with the Jovian clouds and know that ammonia and water are involved in their formation. There’s precipitation, meaning that ammonia and other substances “rain out.” Then, they evaporate. Most of the clouds we do see are thought to be mainly ammonia ice, contaminated with other materials that lend color to the clouds. Ammonia is an important “tracer” of activity in Jupiter’s atmosphere and scientists have studied its presence for years. Most of those measurements come from spacecraft instruments and large ground-based telescopes outfitted with special filters and spectroscopes. Even those observations, however, are limited when it comes to determining their positions in the atmosphere. Also, temporal coverage is limited.

Getting observation time to track the presence of ammonia, and there are only so many spacecraft to go around. Plus, the methods for analyzing the observations are complex and time-consuming. What if there was a quick and cost-effective way to get continual observations of the Jovian clouds? Could smaller telescopes used by amateur astronomers be effective enough to chart variations in the amounts of ammonia in and above Jupiter’s clouds over time? If so, that would fill in a huge gap in Jupiter atmospheric observations.

Measuring Those Clouds

The saga of the Jovian clouds began when Dr. Steven Hill, a space weather forecasting expert, tried a fresh approach and made backyard observations of the gas giant’s clouds in 2020-2021 and 2022-2023. He was able to compare images that show absorption in the atmosphere due to ammonia and methane gases. He also determined variations in the amount of ammonia in and above the cloud tops.

With time on big observatory scopes at such a premium, Hill used a 0.28-meter Celestron Schmidt-Cassegrain telescope, outfitted with a ZWO ASI120MM CMOS camera. He used a 647-nm ammonia band filter first. Later on he applied a 619-nm methane band filter. The idea was to detect individual ammonia abundance features. “I always like to push my observations to see what physical measurements I can make with modest, commercial equipment,” said Hill. “The hope is that I can find new ways for amateurs to make useful contributions to professional work. But I certainly did not expect an outcome as productive as this project has been!”

Applying Hill’s Approach to Jupiter’s Clouds

It turns out Hill’s technique is easier and less expensive than the more complex observational and statistical methods scientists use to map clouds. It can be used in professional research to zero in on specific regions of the atmosphere. The approach also gives citizen scientists with backyard-type telescopes a way to track ammonia and cloud-top pressure variations across features in Jupiter’s atmosphere. That includes Jupiter’s cloud bands, its fast-moving small storms, and even the larger features such as the Great Red Spot.

Planetary atmosphere expert Professor Patrick Irwin at the University of Oxford in England, who co-wrote a paper with Hill about the observations, emphasized the advantage of doing such observations. “I am astonished that such a simple method is able to probe so deep in the atmosphere and demonstrate so clearly that the main clouds cannot be pure ammonia ice,” he said. “These results show that an innovative amateur using a modern camera and special filters can open a new window on Jupiter’s atmosphere and contribute to understanding the nature of Jupiter’s long-mysterious clouds and how the atmosphere circulates.”

Insights into Jupiter’s Clouds

Hill’s initial results showed that the clouds he studied lay in a region of Jupiter’s warm atmosphere that doesn’t allow ammonia ice to exist. In their follow-up study, Irwin and his colleagues applied Hill’s method to observations using the Multi Unit Spectroscopic Explorer on the Very Large Telescope in Chile. Doing spectroscopy allows scientists to measure the visible light fingerprints of the gases in the Jovian atmosphere and chart the distribution of ammonia and the height of its clouds. They also simulated how light interacts with those gases and clouds using a computer model.

Projected variations of ammonia abundance in Jupiter’s clouds, as well as cloud-top pressure near the Great Red Spot and the North Equatorial Dark features. These were made following Hill’s methodology. Courtesy Irwin, et al./JGR.

It turns out that the Jovian clouds observed through Hill’s backyard telescope had to be much deeper than previously thought. They lie in an atmospheric region with higher pressures and higher temperatures. That means the region is too warm to allow ammonia to condense. Chemical reactions created by sunlight’s effect on the gases are very active in Jupiter’s atmosphere. In small regions, where convection (heat transport from one region to another) is especially strong, the updrafts may be fast enough to form fresh ammonia ice. Such regions do exist and have been spotted by spacecraft over the years.

Irwin’s team suggests that when moist, ammonia-rich air gets raised upwards, ammonia gets destroyed. It could also be mixed with photochemical products faster than ammonia ice can form. That means the main cloud deck may actually be composed of ammonium hydrosulphide mixed with photochemical, smoggy products. That’s what produces the red and brown colors we see in Jupiter images. And, this method also works for observations of ammonia clouds in Saturn’s atmosphere. Further work should help determine if the same photochemical processes exist there.

For More Information

Citizen Science Reveals Insight into Jupiter
Clouds and Ammonia in the Atmospheres of Jupiter and Saturn Determined From a Band-Depth Analysis of VLT/MUSE Observations
Spatial Variations of Jovian Tropospheric Ammonia via Ground-Based Imaging

The post Jupiter’s Clouds Contain Smoggy Ammonium Hydrosulphide, Not Ammonia Ice appeared first on Universe Today.

There is a gravitational monster at the heart of our galaxy. Known as Sagittarius A*, it is a supermassive black hole with a mass of more than four million Suns. Long-term observations of the stars closely orbiting Sag A* place it at about 4.3 solar masses, give or take 100,000 or so. Observations of light near its horizon by the Event Horizon Telescope pin the mass down to 4.297 solar masses, give or take about 10,000. Those results are astoundingly precise given how difficult the mass is to measure, but suppose we could determine the mass of our galaxy’s black hole to within a single solar mass. That might be possible with gravitational wave astronomy.

Gravitational wave astronomy is still in its infancy. Presently, our gravitational wave observatories are only sensitive enough to detect the mergers of stellar-mass black holes and neutron stars within the Milky Way. We aren’t able to detect the mergers of supermassive black holes, nor the gravitational waves when a star is consumed by a supermassive black hole. But in the not-too-distant future, we will have space-based gravitational observatories such as LISA. They will be orders of magnitude more sensitive than what we currently have. And as a recent study shows, these new observatories should be sensitive enough to give us ultra-precise measurements of a black hole’s mass and rotation.

The idea behind this work is to focus on brown dwarfs. These objects straddle the mass range between planets and stars. Too large to be a planet, but too small to ignite core fusion like a star. Brown dwarfs have masses between 13 and 78 Jupiters and tend to be roughly the size of our Jovian neighbor. They aren’t quite as common as red dwarf stars, but should be fairly common within the center of our galaxy. That means some brown dwarfs should approach very close to Sag A*. Some of them will surely be gravitationally trapped by the black hole, slowly spiraling ever closer to its event horizon and oblivion. These are the ones the article focuses upon.

The gravitational chirp of a black hole merger. Credit: LIGO

Even the largest brown dwarfs have less than a hundredth the mass of the Sun. They are like specks of dust compared to Sag A*. This means the gravitational dance between a brown dwarf and black hole is an example of an extremely large mass-ratio inspiral (XMRI). The gravitational waves produced by this dance would be small perturbations of the black hole, and as such would be critically dependent on the precise mass and spin of the black hole.

To show just how precise those measurements might be, the team looked at the estimated statistics for brown dwarfs near Sag A* as well as the strength of their gravitational signals. They found that within a typical range of mass and orbital eccentricity, an observatory such as LISA should be able to observe about 20 inspiraling brown dwarfs. This would allow us to determine the mass of Sag A* to better than one part in a million and its spin to one part in 10,000. Those estimates are at the best-case end of what is likely, but it shows that as gravitational wave astronomy improves, we are going to make some outstanding observations.

Reference: Vázquez-Aceves, Verónica, Yiren Lin, and Alejandro Torres-Orjuela. “SgrA* spin and mass estimates through the detection of multiple extremely large mass-ratio inspirals.” arXiv preprint arXiv:2412.20738 (2024).

The post Here's How We Could Measure the Mass of SgrA* to Within One Solar Mass appeared first on Universe Today.

The problem with debating a flat-Earther is that they didn’t arrive at their conclusions from the weight evidence, so using the evidence isn’t going to work to change their minds.

That said, the evidence for the curved Earth is abundant. Besides the enormous body of photographic documentation, it’s even possible to do the experiment yourself. For example, I recently flew from New York City to Doha, from there to Singapore, then to Brisbane, then to Dallas, then back home. I followed an eastward course for my entire journey, and ended up back where I started. That’s only possible on a globe.

On that journey I got to enjoy plenty of views of the night sky, and one of the most striking features was that the sky was different. On a flat Earth, everyone would get the same view of the sky, but there were stars that I could only see at home and couldn’t on my trip, and vice versa.

And lastly, during a lunar eclipse the shadow of the Earth passes over the Moon. That shadow is always a circle, and only spheres are capable of casting circular shadows 100% of the time, regardless of angle.

But like I said, it’s not about the evidence. People who believe that the Earth is flat think that we are being lied to by scientists and political leaders. Many people don’t trust their society, and especially leaders of that society. And most especially elite leaders of that society. Scientists are indeed elite leaders of the government, academia, and other powerful institutions. By claiming that the Earth is flat, people are really expressing a deep distrust of scientists and science itself.

Distrust in science is a deep, thorny issue. But one way to rebuild trust is to simply listen. I know it sounds counter-intuitive, but studies have shown that people tend to trust other people, not necessarily the facts. So if you encounter a flat-Earth, as I have many times, don’t bother getting in a debate. Instead, change the subject so that you focus on something you find wonderful or extraordinary about the universe or about science. Maybe it’s an exciting new observation, or a clever experimental result, or an example of a real-world impact from scientific learning.

By building bridges based on shared wonder, awe, and curiosity, we can defuse the tension, moving around the flashpoint caused by a triggering proclamation and instead focusing on common ground. That’s the only place where trust can take root. And once trust is established, the question of the geometry of the Earth simply fades into the background.

The post How to Debate a Flat-Earther appeared first on Universe Today.

The traditional theory of black hole formation seems to struggle to explain how black holes can merge into larger more massive black holes yet they have been seen with LIGO. It’s possible that they may have formed at the beginning of time and if so, then they may be a worthy candidate to explain dark matter but only if there are enough of them. A team of researchers recently searched for microlensing events from black holes in the Large Magellanic Cloud but didn’t find enough to account for more than a fraction of dark matter. 

Classical black hole formation theory explains how they from the remnants of massive stars that have reached the end of their life and exhausted their fuel. When a star with a mass greater than about 20 times that of the Sun reaches the end of its life, it undergoes a supernova explosion, ejecting most of its outer layers into space. 

3D rendering of a rapidly spinning black hole’s accretion disk and a resulting black hole-powered jet. Credit: Ore Gottlieb et al. (2024)

The core that is left behind is no longer supported by the pressure from nuclear fusion so it collapses under its own gravity. If the core’s mass is sufficient, typically several times the mass of the Sun, it will continue to collapse into a singularity—an infinitely dense point with an extremely strong gravitational pull. This process creates a black hole, characterised by the event horizon, a boundary beyond which nothing, not even light, can escape its gravity.

That’s a widely accepted description of the formation of black holes. However a recent set of observations using gravity wave detectors has identified some massive black holes. When compared to those that can be seen in the Milky Way they bare little resemblance. One possible explanation suggests that they may have instead formed from fluctuations in density during an earlier part of the universe’s history. These are known as primordial black holes and some theories suggest that they may account for dark matter. Possibly even up to 100% of the dark matter to account for the observed black hole merger rates. If they exist in the dark matter halo of the Milky Way then they should be observable by gravitational microlensing events. 

Image from NASA’s Hubble Space Telescope of a galaxy cluster that could contain dark matter (blue-shaded region). (Credit: NASA, ESA, M. J. Jee and H. Ford et al. (Johns Hopkins Univ.))

Previous studies have failed to identify such events but the team believe the observations were not sensitive enough. The paper published by Przemek Mroz from the University of Warsaw and team offer their findings of long-timescale microlensing events (events that occur over extended periods of times from weeks sometimes even years) in the Large Magellanic Cloud over the 20 years of the OGLE (Optical Gravitational Lensing Experiment) survey. The survey began in 1992 and is a long term study to detect microlensing events and observe variable phenomenon such as variable stars and supernova. It’s based at the Las Campanas Observatory in Chile and using the 1.3 metre telescope to monitor sections of sky. 

The Large Magellanic cloud. Credit: CTIO/NOIRLab/NSF/AURA/SMASH/D. Nidever (Montana State University) Image processing: Travis Rector (University of Alaska Anchorage), Mahdi Zamani & Davide de Martin.

Having analysed the 20 years of data they found no events within the timescales longer than a year. Other shorter period events were identified but these are more likely down to stellar events than supermassive primordial black holes (PMB.) They find therefore, that PMB’s up to 6.3 million solar masses cannot make up more than 1% of dark matter. Those in the larger category up to 860 million solar masses cannot compose any more than 10% of dark matter. The unmistakable conclusion is that PMBs, based on the observations in the Large Magellanic Cloud, cannot account for a significant fraction of dark matter.

Source : No massive black holes in the Milky Way halo

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Fast Radio Bursts (FRBs) are mysterious pulses of energy that can last from a fraction of a millisecond to about three seconds. Most of them come from outside the galaxy, although one has been detected coming from a source inside the Milky Way. Some of them also repeat, which only adds to their mystery.

Though astrophysicists think that a high-energy astrophysical process is the likely source of FRBs, they aren’t certain how they’re generated. Researchers used gravitational waves (GWs) to observe one nearby, known source of FRBs to try to understand them better.

The only confirmed FRB source in the Milky Way is a neutron star with a powerful magnetic field—a magnetar—named SGR 1935+2154. Its FRB was detected in 2020 and was the first one to be connected to a source. Though SGR 1935+2154 is around 20,000 light-years away, it’s still close enough to be studied.

In new research in The Astrophysical Journal, scientists used the British-German GEO600 gravitational wave detector to probe any connections between the FRBs and gravitational waves. The research is “A Search Using GEO600 for Gravitational Waves Coincident with Fast Radio Bursts from SGR 1935+2154,” and the lead author is A. G. Abac. Abac is from the Max Planck Institute for Gravitational Physics.

FRBs are extraordinarily energetic, and so are magnetars. Connecting an FRB with the magnetar SGR 1935-2154 is a big step in understanding FRBs, although there are still a whole host of unanswered questions. Some magnetars repeatedly emit FRBs and also glow in X-rays. Magnetars can experience powerful star quakes when tension in their crusts is released, and the released energy shakes the magnetar’s magnetic field, releasing the FRBs and X-rays. Researchers have wondered if those same quakes might generate gravitational waves.

Artist’s conception of a starquake cracking the surface of a neutron star. Credit: Darlene McElroy of LANL

Can observing the magnetar for GWs open a window into magnetars and the processes that generate FRBs?

“Observing fast radio bursts and gravitational waves from a magnetar at almost simultaneously would be the evidence we have been looking for for a long time,” said James Lough, lead scientist of the German-British gravitational-wave detector GEO600 at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute; AEI) in Hanover. A simultaneous observation of FRBs and GWs could confirm the common origin in the stellar quakes generated by the neutron star. “That’s why we worked with an international team to analyze data we took with GEO600 while a magnetar on our cosmic doorstep was emitting fast radio bursts,” adds Lough.

If the magnetar is generating GWs, they’ll be strong when they reach our detectors, and their effects should be easier to observe. Between April 2020 and October 2022, SGR 1935+2154 generated three episodes of FRBs, and GEO600 was listening. The GW detector is part of the global network of GW detectors.

The GEO600 GW detector is near Hanover, Germany. While other GW detectors suffered shutdowns during the COVID-19 pandemic, GEO600 continued to operate. LIGO, for example, resumed operations post-pandemic, including some new upgrades. Image Credit: Max Planck Institute for Gravitational Physics (Albert Einstein Institute)/Milde Marketing

“It was essential that GEO600 could continue observing while all the other detectors were in an upgrade phase,” explained Lough. “Otherwise, we would have missed the opportunity of having gravitational-wave data during these fascinating events occurring so close to us.”

Unfortunately, careful analysis of GEO600’s data showed no evidence of GWs. However, the detector’s observations were still valuable. Since the magnetar is so close to us, even the lack of detection provided some new information.

This isn’t the first time that scientists have used GW detectors to search for GWs emitted simultaneously with FRBs, as well as for GWs from magnetar bursts and pulsar glitches. Different researchers have used the more powerful LIGO, Virgo, and KAGRA (LVK) collaborations to find them without success. “While no detections were found in these studies, the searches have established upper limits on GW energy that may have been emitted in association with these events,” the authors write in their research.

This illustration shows the merger of two supermassive black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. Image Credit: LIGO/T. Pyle

The LVK detectors are larger and more powerful than GEO600. Their data shows that the maximum possible gravitational-wave energy that could have been emitted during the magnetar’s 2020 to 2022 FRBs without being detected must have been up to 10,000 times smaller than astronomers had concluded from previous studies.

Different models explain how GWs are produced in FRBs, and the GW observations aren’t yet sensitive enough to distinguish between them. However, by establishing limits for the strength of the GWs, the GW observations are still providing information that is helping scientists refine their models.

The attempt to link GWs and FRBs is really only beginning. While LIGO/Virgo weren’t able to observe the magnetar during its last FRBs, they will hopefully be operational during the next episode. This time, their effectiveness and sensitivity will have been upgraded.

For a long time, astrophysicists have theorized that magnetars are the source of FRBs, and the detection of FRBs from SGR 1935+2154 confirms this, at least for some FRBs. However, the exact mechanism behind their generation remains elusive. “The relationship between these magnetar bursts and FRBs is poorly understood, but are likely to be caused by different physical processes, even if the underlying magnetar behaviour may be related,” the authors write in their conclusion.

If future GW observations of the magnetar with the upgraded LIGO/Virgo and KAGRA observatories can show that GWs are emitted simultaneously with FRBs, that will be a huge development. “Given the increased sensitivity of these detectors compared to GEO600, any SGR 1935+2154 FRB during the remainder of O4 (Observing Run 4) could provide another opportunity to probe the GW-FRB connection,” the authors of the study explain.

“Things could get exciting really soon. We hope that the magnetar, which has been quiet for two years and has not emitted any radio bursts, will become active again in the next few months,” says Karsten Danzmann, director at the AEI and director of the Institute for Gravitational Physics at Leibniz University Hannover. The international detector network is partway through an observing run that will continue until June 2025. “With the data from the more sensitive instruments, we will be able to look even more closely whether the fast radio burst of magnetars are accompanied by gravitational waves and thus perhaps solve a very old mystery,” says Danzmann.

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The Sun can kill. Until Earth developed its ozone layer hundreds of millions of years ago, life couldn’t venture out onto dry land for fear of exposure to the Sun’s deadly ultraviolet radiation. Even now, the 1% of its UV radiation that reaches the surface can cause cancer and even death.

Astronauts outside of Earth’s protective ozone layer and magnetic shield are exposed to far more radiation than on the planet’s surface. Exposure to radiation from the Sun and elsewhere in the cosmos is one of the main hurdles that must be cleared in long-duration space travel or missions to the lunar and Martian surfaces.

Unfortunately, there’s no harmonized approach to understanding the complexity of the hazard and protecting astronauts from it.

Astronauts haven’t gone further into space than the ISS for decades. But if Artemis lives up to its promise, they’re about to leave Earth and its protective environment behind. Artemis will land astronauts on the Moon, which could be an intermediate step to an eventual landing on Mars. What hazards does radiation pose, and how can astronauts be protected?

A new research editorial in the Journal of Medical Physics examines the issue. It is titled “System of radiological protection: Towards a consistent framework on Earth and in space.” The lead author is Werner Rühm from the Federal Office for Radiation Protection, München (Neuherberg), Germany. The same issue of the Journal of Medical Physics contains several other articles about radiation exposure. Together, they’re part of a research effort by the International Commission on Radiological Protection (ICRP) to update and harmonize radiation exposure guidelines.

The term ‘radiation’ is descriptive enough that most of us recognize the potential threat. However, when it comes to variable space environments and human physiology, the word holds a lot more detail. The authors use the term ‘mixed radiation field’ to describe the radiation environment astronauts must endure.

“The mixed-radiation field outside and within a space vehicle is of particular complexity involving not only low-linear energy transfer (LET) radiation such as gamma radiation, electrons, and positrons but also high-LET radiation such as neutrons and heavy ions,” the authors write. The components of the field contain a wide span of particles with different energy levels. “The quantitative and even qualitative risks of exposure to the combined impact of a complex radiation environment, microgravity, and other stressors remain unclear,” they explain.

One problem in preparing for exposure to these mixed radiation fields is the different approaches taken by different countries and space agencies.

NASA astronauts exploring Mars on future missions, perhaps starting in the 2030s, will require protection from long-term exposure to the cancer-causing space radiation environment. Credit: NASA.

According to lead author Rühm, this disharmony is caused by “the complex and dynamic radiation environments and an incomplete understanding of their biological consequences. Because of this, space agencies follow somewhat different concepts to quantify radiation doses and their resulting health effects.”

This paper and its companions are part of an effort to unify our understanding of radiation and its hazards and to harmonize the various approaches to dealing with them. The goal is to develop a “consistent radiological protection framework.” To do that, the authors explain that several questions need answers:

• Which radiation-induced health effects should be considered?
• What dose quantities are the best for the radiological protection of astronauts?
• Which metrics should be used to quantify radiation-related health risks?
• How do we address sex and age differences in radiation risk?
• What kind of protection criteria should be applied?
• How do we decide on the tolerability of radiation-induced risks, given that astronauts are exposed to many other occupation-related risks?
• How do we deal with the fact that increased health risks due to radiation exposure may persist after an astronaut’s career ends?
• How do we communicate radiation risk and make a comparison with other health hazards in a meaningful way?
• How do we harmonize national radiological protection guidelines, given that different subpopulations might have different levels of risk tolerance?

This list of questions vividly illustrates the complexity of the radiation exposure problem. Answering them will help harmonize the approach to radiation on space missions.

Rühm and his colleagues want to support space agencies as they harmonize and coordinate their guidelines for astronauts’ exposure to radiation. The goal is to develop an approach consistent with the thorough guidelines followed here on Earth.

The difference between how males and females respond to radiation illustrates one of the problems in developing radiation exposure guidelines. In past decades, much medical research was based on males and the results were applied to females as well. According to Rühm, the same thing has happened with radiation.

“It is worth mentioning that on Earth, the System developed by ICRP does not include any systematic differentiation between recommendations on limits for males and females,” the authors write. This is in spite of the fact that it is “well known that there are individual differences in radiation sensitivity between males and females.” The difference is largely because reproductive tissue is more susceptible to radiation than other tissue, and women have more of it.

This infographic shows how men’s and women’s bodies react differently to spaceflight. It’s also becoming well-known that women are more sensitive to radiation exposure. Image Credit: NASA/NSBRI

NASA has developed a different approach to radiation exposure because of this. “This standard is based on a REID (Risk of Exposure-Induced Death) of 3% calculated for cancer mortality in the most vulnerable group of astronauts––35-year-old females,” the authors write. Scientists understand that females are more vulnerable to radiation than males and that younger females are more sensitive than older females. It’s worth noting that astronauts are unlikely to be under the age of 35.

The difference between the sexes isn’t the only thing that needs to be addressed when it comes to astronauts’ exposure to radiation. Different sub-populations might have different risk factors; there are lifestyle-related risks, different mission architectures hold different risks, and many other factors come into play. Harmonizing an approach with all of these different factors is a daunting task.

Difficult or not—and there’s nothing easy about space travel—a harmonized and coordinated approach to understanding the radiation risk is the logical next step. Artemis itself is a collaboration between different nations and agencies, and it’s only fair to the astronauts themselves that they have the same protections and considerations when it comes to radiation exposure.

Rühm and his colleagues hope that their work will help lead to a harmonized approach to assessing the radiation hazards faced by astronauts in mixed radiation fields. We owe it to the people willing to put their lives on the line and serve as astronauts.

“Adventurous people have always tried to widen their horizon, this is part of our very nature as humans,” Rühm says. “Our work contributes to and supports one of the most exciting and challenging human endeavors ever undertaken.”

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In February 2016, scientists working for the Laser Interferometer Gravitational-Wave Observatory (LIGO) made history by announcing the first-ever detection of gravitational waves (GW). These waves, predicted by Einstein’s Theory of General Relativity, are created when massive objects collide (neutron stars or black holes), causing ripples in spacetime that can be detected millions or billions of light years away. Since their discovery, astrophysicists have been finding applications for GW astronomy, which include probing the interiors of neutron stars.

For instance, scientists believe that probing the continuous gravitational wave (CW) emissions from neutron stars will reveal data on their internal structure and equation of state and can provide tests of General Relativity. In a recent study, members of the LIGO-Virgo-KAGRA (LVK) Collaboration conducted a search for CWs from 45 known pulsars. While their results showed no signs of CWs emanating from their sample of pulsars, their work does establish upper and lower limits on the signal amplitude, potentially aiding future searches.

The LVK Collaboration is an international consortium of scientists from hundreds of universities and institutes worldwide. This collaboration combines data from the Laser Interferometer Gravitational-Wave Observatory’s (LIGO) twin observatories, the Virgo Observatory, and the Kamioka Gravitational Wave Detector (KAGRA). The preprint of the paper, “Search for continuous gravitational waves from known pulsars in the first part of the fourth LIGO-Virgo-KAGRA observing run,” recently appeared online.

First discovered in 1967, pulsars are a class of neutron stars that have strong magnetic fields, causing them to emit beams of electromagnetic radiation from their poles. They also rotate rapidly, creating a strobing effect reminiscent of a lighthouse. Given their stability and predictability, pulsars present an opportunity to search for continuous gravitational waves (CWs). Unlike transient GW, which are produced by binary black hole and neutron star mergers, CWs are long-lasting signals expected to come from massive, spinning objects (like pulsars).

To date, all GW events observed by astronomers have been transient in nature. To find evidence of these events, the team searched for signals from 45 known pulsars (and a narrowband search for 16 pulsars) from the first part of the fourth LIGO-Virgo-KAGRA observing run (O4a). They also employed three independent data analysis methods and two different emission models. As they indicated in their paper, no CW signals were detected, but the results were still informative:

“No evidence of a CW signal was found for any of the targets. The upper limit results show that 29 targets surpass the theoretical spin-down limit. For 11 of the 45 pulsars not analyzed in the last LVK targeted search, we have a notable improvement in detection sensitivity compared to previous searches. For these targets, we surpass or equal the theoretical spin-down limit for the single-harmonic emission model. We also have, on average, an improvement in the upper limits for the low-frequency component of the dual-harmonic search for all analyzed pulsars.”

The team also conducted a search for polarization that is consistent with a theory of gravitation alternative to General Relativity (Brans–Dicke theory). While CWs remain unconfirmed, the team predicts that a full analysis of the full O4 dataset will improve the sensitivity of targeted/narrowband searches for pulsars and CWs.

Further Reading: arXiv

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Wood has been a mainstay of human machines and construction for millennia. Its physical properties offer capabilities that are unmatched by almost any synthetic replacements. However, it has only very rarely been used in space. That might change based on the results of a new test run by Japan’s Space Agency (JAXA). LignoSat, one of the world’s first wooden satellites, was deployed from the ISS in December. 

We previously reported on the satellites’ history and launch. Matt’s article here provides an in-depth look at LignoSat’s path to eventual deployment.

Now that LignoSat has officially been deployed, what is it trying to measure? Stress and strain are two big ones that go hand in hand with temperature. Wood can warp with temperature changes, and there is probably still some water left in the honoki magnolia wood panels used for LignoSat’s construction. Understanding those effects on the satellite’s structure is one of the metrics of LignoSat’s makers at the University of Kyoto.

LignoSat is one of three Cubesats being deployed in this photo.
Credit – NASA

The effect of radiation is another. Wood, though an organic substance, is typically housed under the protective umbrella of the ozone layer, protecting it from most of the Sun’s radiation. Several samples of different kinds of wood were exposed to the space environment outside the ISS to test for these effects. However, testing them in full force without shielding the ISS is another of LignoSat’s challenges.

Finally, it will test for geomagnetic interference. Typical satellites are large metal boxes. In electrical engineering terms, we would call that a “Faraday cage,” named after Michael Faraday, the father of modern electrical engineering. Faraday cages are essential to keeping signals either inside or outside the cage and now allowing signals to pass either in or out. That’s why old-style radios used to have antennas that extended outside of their metal housings.

However, a wooden box doesn’t create a Faraday cage, so any electronics inside would be subjected to various geomagnetic interferences. LignoSat’s other job is to determine how severe those interferences are.

Example of the wood joinery technique used to construct the LignoSat, known as a Blind Miter Dovetail Joint.
Credit – Kyoto University

To be fair, the satellite isn’t entirely made of wood—it has aluminum frames and internal steel shafts holding the wood panels in place. However, it is still intended to burn up in Earth’s atmosphere upon reentry in around six months, steel struts and all.

Interestingly, LignoSat uses a traditional Japanese wood joinery technique that will allow the panels to flex during temperature changes, whereas metal fasteners would be much more restrictive and possibly damage the panels. If nothing else, it makes for a beautifully designed box, the outside of which looks more like home decoration than a satellite.

As LignoSat begins collecting data, researchers at the University of Kyoto are already working hard on LignoSat2. It’s scheduled to be launched in 2026, and it promises to add even more aesthetic appeal to the satellite industry while hopefully overcoming some of its technical challenges.

Learn More:
NASA – JAXA’s First Wooden Satellite Deploys from Space Station
UT – Japan Launches the First Wooden Satellite to Space
UT – Japan to Launch ‘Wooden Satellite’ in 2023
UT – Building a Satellite out of Wood? Use Magnolia

Lead Image:
Internal view of LignoSat’s structure shows the relationship among wooden panels, aluminum frames, and stainless-steel shafts.
Credit: Kyoto University

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It’s easy to forget that, despite life having existed on Earth for billions of years and despite our relatively carefree existence from total destruction, throughout history there have been events that wiped out nearly everything! Fortunately for many life forms, they have the ability to go dormant and enter a state of reversible, reduced metabolic activity. In this state they are protected from decay and can survive long harsh periods where life would otherwise not survive. Is it just possible therefore that dormancy could also allow life to survive on other worlds like Mars or Venus? 

‘Life, don’t talk to me about life,’ were the utterances of Marvin the depressive robot on the Hitchhikers Guide to the Galaxy. Unlike Marvin, it seems humanity loves talking about and exploring the possibilities that life may exist elsewhere in the universe. A discussion about life is always tricky though as life could, conceivably come in such a strange form that we might not even recognise it as life. Typically if we talk about searching for alien life of any level of existence, we tend to consider life like that which we find here on planet Earth. After all, we have to start somewhere. 

With thousands of exoplanets discovered so far, astronomers are learning how different planets can be. What if intelligent alien civilizations arise on extremely different habitable worlds? Some civilizations could develop space exploration technologies, but others would be trapped underwater, under ice, or in enormous gravity wells. How could they escape? Image Credit: DALL-E

Exploring the diversity of life on Earth gives us an insight into what critters might be out there in similar environments. One such state that is surprisingly common across Earthly organisms is the ability to enter the state known as dormancy. The process protects an inactive organism and minimises the chances of extinction by preserving the critical bodily functions and shutting down all others, but just temporarily. In a paper recently published in The Royal Society Journals, Kevin D. Webster and Jay T. Lennon explore dormancy theory in consideration of its enabling life to flourish elsewhere in the cosmos. 

The duo first analysed the key activities that led to the evolution of intelligent life; the supply of chemical building blocks at the necessary rate to exceeded their decay and that some sort of compartmentalisation was needed for early primative life to offer protection between their cellular components and the environment. The sustained evolution of life from these early stages was susceptible to chance events but also error in DNA replications that may have brought a species to an evolutionary dead end. 

Deoxyribonucleic acid (DNA) is the genetic material for all known life on Earth. DNA is a biopolymer consisting of a string of subunits. The subunits consist of nucleotide base pairs containing a purine (adenine A, or guanine G) and a pyrimidine (thymine T, or cytosine C). DNA can contain nucleotide base pairs in any order without its chemical properties changing. This property is rare in biopolymers, and makes it possible for DNA to encode genetic information in the sequence of its base pairs. This stability is due to the fact that each base pair contains phosphate groups (consisting of phosphorus and oxygen atoms) on the outside with a net negative charge. These repeated negative charges make DNA a polyelectrolyte. Computational genomics researcher Steven Benner has hypothesized that alien genetic material will also be a polyelectrolyte biopolymer, and that chemical tests could therefore be devised to detect alien genetic molecules. Credit: Zephyris

Despite the sequence of events that brought about evolution that shaped our history there were events that momentarily brought a pause to proceedings. There have been five extinction events since the formation of Earth and it is the ability to drive through these dark days that dormancy really comes into its own. 

Impactors strike during the reign of the dinosaurs (image credit: MasPix/devianart)

Dormancy is a state of reduced activity or metabolism that organisms enter to survive during periods of challenging environmental conditions, such as extreme temperatures or reduced levels of light. This survival mechanism is common in plants, seeds, and certain animals, enabling them to withstand harsh seasons or environments. For animals, dormancy may take the form of hibernation or estivation, where metabolic rates decrease to conserve energy until conditions improve.

Dormancy provides protection, allowing inactive organisms to survive during unfavourable conditions and resume activity once more better conditions return. It may not have just helped organisms to survive harsh seasons but may have protected life from extinction during catastrophic events. It seems that the ability for primitive organisms to evolve dormancy processes is quite simple. If this is the case then it is quite plausible that any organisms that evolved on other planets with less than favourable conditions could be in their dormant state and waiting for conditions to improve. 

Source : Dormancy in the origin, evolution and persistence of life on Earth

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