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Venus is known for being really quite inhospitable with high surface temperatures and Mars is known for its rusty red horizons. Even the moons of some of the outer planets have fascinating environments with Europa and Enceladus boasting underground oceans. Recent observations from the James Webb Space Telescope show that Ariel, a moon of Uranus, is also a strong candidate for a sub surface ocean. How has this conclusion been reached? Well JWST has detected carbon dioxide ice on the surface on the trailing edge of features trailing away from the orbital direction. The possible cause, an underground ocean!

Uranus is the seventh planet in the Solar System and has five moons. Ariel is one of them and is notable for its icy surface and fascinatingly diverse geological features. It was discovered back in 1851 by William Lassell who funded his love of astronomy from his brewing business! The surface of Ariel is a real mix of canyons, ridges, faults and valleys mostly driven by tectonic activity. Cryovolcanism is a prominent process on the surface which drives constant resurfacing and has led to Ariel having the brightest surface of all Uranus’ moons. 

Image of Uranus from Webb

Studying Ariel closeup reveals that the surface is coated with significant amounts of carbon dioxide ice. The trailing hemisphere of Ariel seems to be particularly coated in the ice which has surprised the community. At the distance of Uranian system from the Sun, an average of 2.9 billion kilometres, carbon dioxide will usually turns straight into a gas and be lost to space, it’s not expected to freeze!

Until recently, the most popular theory that supplies the carbon dioxide to Ariel’s surface is interactions between its surface and charged particles in the magnetosphere of Uranus. The process known as radiolysis breaks down molecules through ionisation. A new study just published in the Astrophysical Journal Letters suggests an intriguing alternative, the carbon dioxide molecules are expelled from Ariel, possibly from a subsurface liquid ocean!

A team of astronomers using JWST have undertaken a spectral analysis of Ariel and compared the results with lab based findings. The results revealed that Ariel has some of the most carbon dioxide rich deposits in the solar system. The deposits are not just wisps and trace amounts instead adding up to about 10 millimetres across the trailing hemisphere. Furthermore, the results also showed signals from carbon monoxide too which should not be there given the average temperatures. 

Illustration of James Webb Space Telescope

It is still possible that radiolysis is responsible for at least some of the deposits but the replenishment from the subsurface ocean is thought to be the main contributor. This hypothesis has been supported by the discovery of signals from carbonate minerals, salts that can only be present due to the interaction between rock and water. 

The only way to be absolutely sure is for a future space mission to Uranus. Such a mission will undoubtedly explore the moons of Uranus. Ariel is covered in canyons, fissures and grooves and it is suspected these are openings to its interior. A robotic explorer in the Uranian system will be able to uncover the origin of the carbon oxides on Ariel. Without such a mission we are still somewhat in the dark given that Voyager 2 only imaged around 35% of the moon’s surface. 

Source : Carbon Oxides on Uranus’ Moon Ariel Hint at Hidden Ocean, Webb Telescope Reveals

The post Now Uranus’ Moon Ariel Might Have an Ocean too appeared first on Universe Today.

The Perseverance rover has found some of the most promising hints of ancient Martian life yet, but we can’t know for sure until its samples are sent back to Earth

When the James Webb Space Telescope was launched it came with a fanfare expecting amazing things, much like the Hubble Space Telescope. One of JWST’s most anticipated target was TRAPPIST-1. This inconspicuous star is host to seven Earth-sized planets, with at least three in the habitable zone. The two inner planets are airless worlds but so far there has been no word of the third planet, the first in the habitable zone. The question is why and what makes it so tricky to observe?

TRAPPIST-1 is a red dwarf star about 41 light years in the constellation Aquarius. The interest in the planets in the habitable zone is that the conditions could allow for the existence of liquid water. The seven planets were discovered through transit photometry where tiny drops in brightness of the star are observed due to the passage of the planets in front of the star.  The planets that orbit the star all have fairly short orbital periods from 1.5 days to 20 days. The result of this is that their transits across the stellar surface often overlap. 

The launch of the JWST in 2021 reignited the interest in exoplanet studies. Its predecessor the Hubble Space Telescope was never expected to last as long to JWST was able to complement the famous telescope. Setting itself apart from Hubble by its advanced infrared capability, JWST was ideally placed to study exoplanet atmospheres. Fundamental to the operation of the JWST is a large, multi-segment mirror measuring 6.5 metres in diameter and a whole host of sophisticated instruments. 

Artist impression of the James Webb Space Telescope

A team of astronomers have been studying TRAPPIST-1 and its system of planets using JWST, exploiting its infrared capabilities. Using a technique known as transmission spectroscopy the starlight is explored as it passes through the planetary atmospheres as they pass in front of the star. Studying the light in this way can reveal the elements in the atmosphere. Three years in though and challenges have slowed them down. 

Now, a paper published in Nature Astronomy highlights the challenges they faced and proposes how to overcome them. Top of the list relates to the non uniformity of a star. Those interested in solar astronomy will already be familiar with sun spots, flares and other solar phenomenon. These are seen on stars too and regions where cooler regions form can often harbour water vapour, playing havoc with transmission spectra and making it difficult to identify elements in the planetary atmosphere rather than in the star. This is known as stellar contamination. 

Previous issues like this have been seen by astronomers studying exoplanet atmospheres using Earth based telescopes like the Magellan Telescope in Chile. Previously however, these issues were often simply ignored but the greater sensitivity of JWST causes more of a problem. There is a relatively simple work around however by observing the star as it rotates to build a picture of the stellar surface, allowing a more accurate analysis of the planetary atmosphere. 

Magellan Telescope

Using TRAPPIST-1 as a test bed, it is hoped that other challenges and their solutions can be tested before being applied to other, less easy to observe explanatory systems. The team propose that the exoplanet and JWST community work together on research projects to maximise efficiency in driving out solutions to other challenges in the road ahead. 

Source : Roadmap details how to improve exoplanet exploration using the JWST

The post Why is JWST Having So Much Trouble with the TRAPPIST-1 System? appeared first on Universe Today.

The extrasolar planet census recently passed a major milestone, with 5500 confirmed candidates in 4,243 solar systems. With so many exoplanets available for study, astronomers have learned a great deal about the types of planets that exist in our galaxy and have been rethinking several preconceived notions. These include the notion of “habitability” and whether Earth is the standard by which this should be measured – i.e., could there be “super habitable” exoplanets out there? – and the very concept of the circumsolar habitable zone (CHZ).

Traditionally, astronomers have defined habitable zones based on the type of star and the orbital distance where a planet would be warm enough to maintain liquid water on its surface. But in recent years, other factors have been considered, including the presence of planetary magnetic fields and whether they get enough ultraviolet light. In a recent study, a team from Rice University extended the definition of a CHZ to include a star’s magnetic field. Their findings could have significant implications in the search for life on other planets (aka. astrobiology).

The research team consisted of Anthony S. Atkinson, a graduate student with the Department of Physics and Astronomy at Rice University, Professor David Alexander, the director of the Rice Space Institute and member of the Texas Aerospace Research and Space Economy Consortium, and Alison O. Farrish, a NASA Postdoctoral Program Fellow at NASA’s Goddard Space Flight Center. The paper describing their findings, “Exploring the Effects of Stellar Magnetism on the Potential Habitability of Exoplanets,” appeared on July 9th in The Astrophysical Journal.

Artist’s impression of exoplanets orbiting different types of stars. Credit: NASA/W. Stenzel

On Earth, the presence of an intrinsic magnetic field has been vital to the emergence and evolution of life as we know it. Without it, our atmosphere would have been stripped away long ago by energetic particles emanating from the Sun – which was the case with Mars. In addition to Earth’s atmosphere, our planet’s magnetic field ensures that a limited amount of solar radiation and cosmic rays reach the surface. For this reason, astrobiologists consider a planetary magnetic field essential for determining whether or not an exoplanet is habitable.

Another factor is how the strength of a planet’s magnetic field and its interaction with its parent star’s magnetic field affect habitability. Not only does an exoplanet require a strong field to shield it against stellar activity (solar flares, etc.), but it must also orbit far enough to avoid a direct magnetic connection with its star. “The fascination with exoplanets stems from our desire to understand our own planet better,” said Prof. Alexander in a recent Rice University press statement. “Questions about the Earth’s formation and habitability are the key drivers behind our study of these distant worlds.”

The magnetic interactions between planets and their parent stars are known as “space weather.” For their study, the team examined 1,546 exoplanets to determine if they orbited inside or outside their host star’s Alfvén radius – the distance where stellar wind decouples from the star. This consisted of characterizing the stars’ activity known using their Rossby number (Ro) – the ratio between a star’s rotational period to their convective turnover time.

Planets orbiting within this radius would directly interact magnetically with the star’s corona, leading to significant atmospheric stripping, ruling them out as viable candidates for habitability. This phenomenon has been observed with TRAPPIST-1 and its system of seven exoplanets. After examining the exoplanets in their study, they found that only two planets met all the conditions for potential habitability. These were K2-3 d and Kepler-186 f, two Earth-sized exoplanets 144 and 579 light-years from Earth (respectively).

Illustration of Kepler-186f, a possible Earth-like exoplanet that could be a host to life. Credit: NASA Ames, SETI Institute, JPL-Caltech, T. Pyle

These planets orbit within their stars’ CHZ, lie outside their Alfvén radius, and have strong enough magnetic fields to protect them from stellar activity. “While these conditions are necessary for a planet to host life, they do not guarantee it,” said Atkinson. “Our work highlights the importance of considering a wide range of factors when searching for habitable planets.”

These findings highlight the need for continuous observation when studying exoplanet systems and considering what factors have led to the emergence of life here on Earth. They are also indicative of current efforts among astronomers and astrobiologists to refine the definition of “Habitable Zone” and create a more nuanced understanding. In so doing, this research could help refine the search for extraterrestrial life by allowing scientists to further constrain where they should be looking.

Further Reading: Rice University, The Astrophysical Journal

The post Planetary Habitability Depends on its Star’s Magnetic Field appeared first on Universe Today.

Supermassive Black Holes are Nature’s confounding behemoths. It’s difficult for Earth-bound minds to comprehend their magnitude and power. Astrophysicists have spent decades studying them, and they’ve made progress. But one problem still baffles even them: the Final Parsec Problem.

New research might have solved the problem, and dark matter plays a role in the solution.

Supermassive Black Holes (SMBHs) can be billions of times more massive than our Sun. Evidence shows that they may reside at the center of all large galaxies. The Milky Way has one and it’s named Sagittarius A* (Sgr A*).

SMBHs grow so massive by merging with other SMBHs when their host galaxies merge. But there’s a problem. Astrophysicists don’t understand how the two SMBHs can close the final parsec that separates them.

When black holes merge, they begin as a binary object. They spiral around each other, each carrying their own momentum. To merge, the black holes need to shed energy. To do this, they shed energy to the surrounding gas and dust which then dissipates. But when they get about three light-years away from one another, or about one parsec, there simply isn’t enough gas and dust to absorb the necessary energy.

Yet SMBHs do merge, so somehow, nature overcomes the Final Parsec Problem (FPP).

New research published in the journal Physical Review Letters presents a solution to the FPP. The research is titled “Self-Interacting Dark Matter Solves the Final Parsec Problem of Supermassive Black Hole Mergers.” The first author is Gonzalo Alonso-Álvarez, a Postdoctoral Fellow in the Department of Physics at the University of Toronto, Canada.

“Our work is a new way to help us understand the particle nature of dark matter.”

Gonzalo Alonso-Álvarez, Department of Physics, University of Toronto

There’s no question that stellar-mass black holes can merge. LIGO/Virgo has sensed the gravitational waves coming from many mergers between stellar-mass black holes, which is direct evidence that black holes can merge. However, evidence for SMBH mergers is elusive.

In 2023, scientists announced the detection of a persistent background hum of gravitational waves. That detection came from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav.) NANOGrav gathered gravitational wave data for 15 years using pulsar timing.

Different groups of researchers hypothesized that the hum comes from the mergers of SMBHs. In one paper, researchers said the hum comes from hundreds of thousands of pairs of merging SMBHs. Somehow, these SMBHs are overcoming the FPP.

In their new paper, Alonso-Álvarez and his co-researchers show how dark matter allows SMBHs to merge despite the Final Parsec Problem. “We show that including the previously overlooked effect of dark matter can help supermassive black holes overcome this final parsec of separation and coalesce,” said Alonso-Álvarez. “Our calculations explain how that can occur, in contrast to what was previously thought.”

Astrophysicists have been working on the FPP for a long time. Different researchers have developed different models to try to explain how SMBHs merge, and those models include dark matter. However, previous merger models showed that the dark matter near the spiralling black holes is thrown clear of the merger area by the gravity created by the inspiralling holes. Without that dark matter to absorb energy, the pair of SMBHs can’t overcome the FPP.

But in this new research, dark matter interacts with itself and ‘spikes’ instead of being dispersed. Dark matter spikes are theoretical concentrations of dark matter around a black hole. As an SMBH grows, it draws regular matter towards itself. The same process could lead to a spike in dark matter around the black hole. Its density remains high enough that it can absorb enough energy for the pair of SMBHs to continue their inspiralling. Eventually, they overcome the FPP and coalesce into one.

This figure from separate research shows a spike in dark matter near a black hole. The vertical axis shows the dark matter’s density in solar masses per cubic parsec, and the horizontal axis shows the distance to the black hole center in parsecs. The black line shows the initial distribution of dark matter, and the pink line shows the spike that occurs due to adiabatic growth. Image Credit: Wierda 2023.

It all depends on dark matter self-interacting.

“The possibility that dark matter particles interact with each other is an assumption that we made, an extra ingredient that not all dark matter models contain,” said Alonso-Álvarez. “Our argument is that only models with that ingredient can solve the final parsec problem.”

Physicists aren’t certain that dark matter can interact with itself, though. The Standard Model says that dark matter interacts primarily through gravity. But newer evidence is accumulating that it can interact with itself, and physicists call this the Self-Interacting Dark Matter theory.

Other research has looked at dark matter spikes near merging black holes. According to that research, dynamical friction between the black holes and the DM spike could dissipate the spike. However, this new research argues that only SIDM can effectively move the heat outwards and replenish the DM spike. Contrary to collisionless dark matter, an SIDM spike maintains itself and allows the inspiralling black holes to shed enough energy and cross the final parsec problem.

More support for this hypothesis comes from the nature of the background gravitational wave hum that scientists announced in 2023. It was measured by pulsar timing and the waves displayed a softening at low frequencies. According to Alonso-Álvarez, their model predicts this phenomenon, lending credence to their work.

“A prediction of our proposal is that the spectrum of gravitational waves observed by pulsar timing arrays should be softened at low frequencies,” said co-author Professor James Cline from McGill University and the CERN Theoretical Physics Department in Switzerland. “The current data already hint at this behavior, and new data may be able to confirm it in the next few years.”

This research reaches beyond SMBH mergers to the nature of dark matter itself. The self-interactions the researchers modelled can help explain the shape of dark matter haloes around galaxies.

“Our work is a new way to help us understand the particle nature of dark matter,” said Alonso-Álvarez. “We found that the evolution of black hole orbits is very sensitive to the microphysics of dark matter and that means we can use observations of supermassive black hole mergers to better understand these particles.”

“Despite astrophysical uncertainties about their detailed nature, there is no doubt that dark matter spikes exist around supermassive black hole binaries and thus contribute to the dynamical friction accelerating the decay of their orbit,” the authors write in the conclusion of their paper.

“We found that the final parsec problem can only be solved if dark matter particles interact at a rate that can alter the distribution of dark matter on galactic scales,” said Alonso-Álvarez. “This was unexpected since the physical scales at which the processes occur are three or more orders of magnitude apart. That’s exciting.”

The post A Solution to the “Final Parsec Problem?” appeared first on Universe Today.

A type of invisible, unpredictable air turbulence is expected to occur more frequently in the Northern Hemisphere as the climate warms. Known as clear air turbulence, the phenomenon also increased in the Northern Hemisphere between 1980 and 2021.

In October 2022, astronomers were stunned by what was quickly dubbed the BOAT -- the brightest-of-all-time gamma-ray burst (GRB). Now an international science team reports that data from NASA's Fermi Gamma-ray Space Telescope reveals a feature never seen before.

Scientists transformed existing optoelectronic devices into ones that can control electron spin at room temperature, without a ferromagnet or magnetic field. Researchers replaced the electrodes of store-bought LEDs with a patented spin filter made from hybrid organic-inorganic halide perovskite.

Danish Tycho Brahe was most famous for his contributions to astronomy. However, he also had a well-equipped alchemical laboratory where he produced secret medicines for Europe's elite.

Researchers demonstrated a novel technique to efficiently convert ambient low-power radiofrequency signals into DC power. This 'rectifier' technology can be easily integrated into energy harvesting modules to power electronic devices and sensors, enabling battery-free operation.

A team has been developing a new type of laser-induced forward transfer (LIFT) for laser printing using an optical vortex, which has been dubbed OV-LIFT. The team succeeded in printing crystals with helix-like twisted structures, which could hold promise in creating printable magnetic devices for high-density data storage.

A team has been developing a new type of laser-induced forward transfer (LIFT) for laser printing using an optical vortex, which has been dubbed OV-LIFT. The team succeeded in printing crystals with helix-like twisted structures, which could hold promise in creating printable magnetic devices for high-density data storage.

Chemists have synthesized materials that can improve solar elements for indoor use. Such photovoltaic cells, which can also be integrated into various electronic devices, generate electricity even in low-light conditions.

Chemists have synthesized materials that can improve solar elements for indoor use. Such photovoltaic cells, which can also be integrated into various electronic devices, generate electricity even in low-light conditions.

Non-reciprocal interactions allow the design of more efficient molecular systems. Scientists now propose a mechanism on how energy barriers in complex systems can be overcome. These findings can help to engineer molecular machines and to understand the self-organization of active matter.

Non-reciprocal interactions allow the design of more efficient molecular systems. Scientists now propose a mechanism on how energy barriers in complex systems can be overcome. These findings can help to engineer molecular machines and to understand the self-organization of active matter.

Researchers are investigating ways to better plan for climate-resilient energy systems in the Global South. Focusing on the case study of Accra, the capital of Ghana, the multidisciplinary team expanded conventional energy system modeling approaches by incorporating a range of socio-techno-economic challenges, climate change impacts, and resilience metrics into their models. Their approaches are applicable worldwide to support widespread sustainable and resilient energy system transitions.

In a scientific breakthrough, an international research team has developed a quantum sensor capable of detecting minute magnetic fields at the atomic length scale. This pioneering work realizes a long-held dream of scientists: an MRI-like tool for quantum materials.

In a scientific breakthrough, an international research team has developed a quantum sensor capable of detecting minute magnetic fields at the atomic length scale. This pioneering work realizes a long-held dream of scientists: an MRI-like tool for quantum materials.

Using two optically trapped glass nanoparticles, researchers observed a novel collective Non-Hermitian and nonlinear dynamic driven by nonreciprocal interactions. This contribution expands traditional optical levitation with tweezer arrays by incorporating the so called non-conservative interactions.