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After a few days of wakefulness, Japan’s SLIM moon lander has gone dormant once more at the start of a 14-day-long lunar night. The upended robot sent back a stream of data and imagery while its solar cells were in position to soak up sunlight, and its handlers hope they can get SLIM to wake up again and resume its work after lunar sunrise in mid-February.

The car-sized robot accomplished its primary mission on Jan. 20 (Japan time) when it landed within 100 meters of its target point near Shioli Crater. SLIM — which is an acronym standing for “Smart Lander for Investigating Moon” — was designed to demonstrate a precision landing technique that Japan hopes to use for future missions to the moon and Mars.

Unfortunately, the lander ended up in an upside-down position, with its solar cells pointing off to the side. Mission managers were able to get some data and pictures back — including a photo captured by a mini-robot that documented the lander’s predicament. But within hours, the lander’s batteries ran down to the point that SLIM had to go into hibernation. The mission team could only hope that as the sun moved westward in the lunar sky, enough light would eventually hit the panels to allow for a reawakening.

That’s exactly what happened on Jan. 28: The Japan Aerospace Exploration Agency, a.k.a. JAXA, re-established contact with the charged-up SLIM and commanded the lander to transmit a set of multispectral images showing the area around the landing site — including a variety of rocks named after canine breeds, such as Bulldog, Toy Poodle and Aki Inu.

??????????????????SLIM???????????????MBC????10??????????????
??https://t.co/VtNFaNHqOe#JAXA #SLIM #???
?????????JAXA???????????? pic.twitter.com/RgArA9kSMX

— ISAS?JAXA???????? (@ISAS_JAXA) February 1, 2024 This Japanese-language posting shows a variety of rocks around the lander, plus a closeup focusing on a rock that was named Aki Inu.

Communication with SLIM was successfully established last night, and operations resumed! Science observations were immediately started with the MBC, and we obtained first light for the 10-band observation. This figure shows the “toy poodle” observed in the multi-band observation. pic.twitter.com/WYD4NlYDaG

— ????????SLIM (@SLIM_JAXA) January 29, 2024

SLIM’s recent science-gathering session was limited to just a few days due to the moon’s day-night cycle. By the time the lander’s solar cells soaked up enough sunlight, it was the equivalent of late afternoon on the moon. Sunset came on Feb. 1, and once again, SLIM went into hibernation.

“We sent a command to switch on SLIM’s communicator again just in case, but with no response, we confirmed SLIM had entered a dormant state,” the mission team at the Japan Aerospace Exploration Agency said in a posting on X / Twitter.

The final image sent back by the lander shows a dark stretch in the foreground, with the sun’s dying rays reflecting off rocks and off the heights of a ridge rising in the background.

Temperatures were expected to fall to somewhere around 200 degrees below zero Fahrenheit (-130 degrees Celsius) during the lunar night. JAXA initially had planned to let the lander go dead when the sun went down — but in light of the unlucky lander’s recent resilience, those plans could change.

“Although SLIM was not designed for the harsh lunar nights, we plan to try to operate again from mid-February, when the sun will shine again on SLIM’s solar cells,” mission managers said.

Last image from #SLIM (JAXA, 2024.01.31) – The world on the moon alternates between 14 days of day and 14 days of night. This photo was taken of the SLIM landing site just before sunset. Compared to the photo taken immediately after landing, the area that is darkened by the… pic.twitter.com/q5OcA8clEE

— AMSAT-DL (@amsatdl) January 31, 2024

The post Japan Moon Lander Sleeps After Sending Science — Will It Wake Up Again? appeared first on Universe Today.

The rise of “floatovoltaics’ could reduce pressure to build large solar farms on land, but some researchers are concerned about the impact on aquatic ecosystems

The Vera Rubin Observatory (VRO) is different than other large telescopes, and that difference makes it more vulnerable to space junk. Other telescopes, like the Giant Magellan Telescope and the European Extremely Large Telescope, focus on distant objects. But the VRO’s job is to repeatedly image the entire available night sky for ten years, spotting transients and variable objects.

All that space junk can look like transient events, impairing the VRO’s vision and polluting its results.

In a new research note awaiting publication, Harvard physicist/astronomer Avi Loeb points out how space junk will affect the VRO’s work. The paper is “Flares from Space Debris in LSST Images.” LSST is the Legacy Survey of Space and Time, the VRO’s primary observing effort.

The problem stems from space junk and also the VRO’s extreme sensitivity, a critical part of its success. “Owing to the exceptional sensitivity of the Vera C. Rubin Observatory, we predict that its upcoming LSST images will be contaminated by numerous flares from centimetre-scale space debris in Low Earth Orbits (LEO),” Loeb writes. “Millisecond-duration flares from these LEO objects are expected to produce detectable image streaks of a few arcseconds with AB magnitudes brighter than 14.”

This NASA video is a representation of space junk orbiting Earth. The debris is obviously not scaled to Earth, but it shows where the greatest orbital debris populations are. Credit: NASA.

Our space junk problem is getting worse, as everyone knows. The ESA says that as of December 6th, 2023, there are 130 million objects in the size range of 0.1-1 cm orbiting Earth. There are also one million objects between 1-10 cm and 36,500 objects larger than 10 cm. With so many launches, the problem is getting worse. Space is a burgeoning economy, and a certain amount of junk goes with it.

Not all of those objects are in the critical Low-Earth Orbit region, but a large subset of them are. According to Loeb, this population of debris has implications for the VRO. “In this Note, we examine the implications of this LEO debris for the upcoming Legacy Survey of Space & Time (LSST) of the Vera C. Rubin Observatory in Chile,” Loeb writes.

When it comes to the VRO’s images, it’s not really the size of the debris that matters. An object’s albedo is the real problem. Albedo can scale with size, but not always.

There’s no way to measure the individual albedos of pieces of space junk, but in this work, Loeb calculates albedo by combining an object’s radius and distance with one of its sides illuminated by the Sun. That yields the fraction of light that it will reflect.

We already know how space junk can reflect light because we can see it with the Zwicky Transient Facility. It’s similar to the VRO in that it detects transient light sources. “Data from the Zwicky Transient Facility (ZTF) shows that the sunlight glints from known LEO satellites generate flashes of duration 10?3±0.5 s.” That’s an extremely brief flash.

But the VRO and its LSST will visit each patch of the sky for 30 seconds and take back-to-back 15-second exposures. The problem is that debris is moving, and rather than just a flash, it creates a streak. “The light from the flares is therefore expected to spread across no more than a few arcseconds, independently of the LSST exposure time which is 4 orders of magnitude longer,” Loeb writes.

What does that mean for the VRO?

It’s not good. According to Loeb, the number of objects that can create problematic streaks “exceeds by an order of magnitude” the number of large satellites orbiting Earth. USA’s Space Surveillance Network regularly tracks satellites and has built a catalogue of orbiting objects that could help the VRO manage the problem. But as Loeb points out, “Out of the entire debris population, only 3.515 × 104 (351,500) objects are regularly tracked and catalogued by Space Surveillance Networks.”

This infographic shows the populations of satellites in different orbits and how urgent it is to clean these orbits. Note the LEO “needs urgent protection,” according to the maker. While it’s primarily about satellites, it drives the space debris problem point home. Image Credit: By Pablo Carlos Budassi – Own work, CC BY 4.0, https://commons.wikimedia.org/w/index.php?curid=140585562

Streaks of light in images are only part of the problem. There’s the more generalized problem of the combined light from all satellites and debris. Other researchers have examined the problem and its effects on ground-based astronomy. A March 2023 paper in Nature Astronomy showed that by 2030, reflected light from space junk and functioning satellites will increase the diffuse background brightness for the VRO by 7.5%. That means the VRO’s LSST will be 7.5% less efficient. That’ll add over $20 million US to the cost of the 10-year-long LSST.

Satellites and their predictable orbits mean they should be easier to deal with. In fact, the LSST team has a plan to deal with satellites. They propose an updated scheduler that can mitigate the problem. “Overall, sacrificing 10% of LSST observing time to avoid satellites reduces the fraction of LSST visits with streaks by a factor of 2,” the authors of a paper in The Astrophysical Journal Letters write.

But junk is far more abundant. Without a solution, will LSST images be littered with noisy streaks?

It seems irrational to download the responsibility for space debris to the people trying to see the sky through it. Any long-term solution has to include two things: the cleaning up of Low Earth Orbit and an international agreement to stop polluting it even further.

The ESA is coming to terms with the space debris problem. “130 million pieces of space debris larger than a millimetre orbit Earth, threatening satellites now and in the future,” the ESA wrote when announcing their Zero Debris Charter. “Once a week, a satellite or rocket body reenters uncontrolled through our atmosphere. Behaviours in space have to change.” While the Charter is primarily aimed at reducing the risk of collisions, it will benefit ground-based astronomy.

NASA is seeking solutions, too. Their Detect, Track, and Remediate: The Challenge of Small Space Debris competition is reaching out to people around the globe for innovative solutions to the problem.

Those are great initiatives, but the VRO is scheduled to see its first light in early January 2025. A solution to the problem of satellites and satellite constellations in space is likely within reach. But debris is a much thornier problem.

“However, the above numbers suggest that image contamination by untracked space debris might pose a
bigger challenge,” Loeb concludes.

The post Space Junk is Going to be a Problem for Vera Rubin appeared first on Universe Today.

On December 5th, 2020, Japan’s Hayabusa2 mission successfully returned samples it had collected from the Near-Earth Asteroid (NEA) 162173 Ryugu home. Since asteroids are basically leftover material from the formation of the Solar System, analysis of these samples will provide insight into what conditions were like back then. In particular, scientists are interested in determining how organic molecules were delivered throughout the Solar System shortly after its formation (ca. 4.6 billion years ago), possibly offering clues as to how (and where) life emerged.

The samples have already provided a wealth of information, including more than 20 amino acids, vitamin B3 (niacine), and interstellar dust. According to a recent study by a team of Earth scientists from Tohoku University, the Ryugu samples also showed evidence of micrometeoroid impacts that left patches of melted glass and minerals. According to their findings, these micrometeoroids likely came from other comets and contained carbonaceous materials similar to primitive organic matter typically found in ancient cometary dust.

The team was led by Megumi Matsumoto, an assistant professor from the Earth Science Department at Tohoku University’s Graduate School of Science. He was joined by researchers from the Division of Earth and Planetary Sciences at Kyoto University, the CAS Center for Excellence in Deep Earth Science, the Institute of Space and Astronautical Science (ISAS), the Japan Synchrotron Radiation Research Institute (JASRI), the Japan Aerospace Exploration Agency (JAXA), and NASA’s Johnson Space Center. The details of their findings were presented in a paper that recently appeared in the journal Science Advances.

An artist’s conception shows Hayabusa 2’s sample return capsule making its atmospheric re-entry as its mothership flies above. Credit: JAXA Illustration

Like the Moon and other airless bodies, Ryugu has no protective atmosphere and does not experience weathering or erosion. This ensures that craters caused by past impacts on its surface (which is directly exposed to space) are carefully preserved despite the passage of eons. These impacts generate intense heat that leaves behind melted patches of glass (aka. “melt splashes”), which quickly solidify in the vacuum of space. These impacts cause changes to the composition of the asteroid’s surface materials, revealing information about the history of impacts.

After analyzing the Ryugu samples, Matsumoto and her colleagues found melt splashes ranging in size from 5 to 20 micrometers. Their composition suggests they came from cometary sources that impacted Ryugu while it was in a near-Earth orbit. “Our 3D CT imaging and chemical analyses showed that the melt splashes consist mainly of silicate glasses with voids and small inclusions of spherical iron sulfides,” said Matsumoto in a recent Tohoku University news release. “The chemical compositions of the melt splashes suggest that Ryugu’s hydrous silicates mixed with cometary dust.”

Their analysis revealed small carbonaceous materials with a spongy texture indicative of nano-pores, small voids caused by the release of water vapor from hydrous silicates. This vapor was subsequently captured in the melt splashes, which also contained silicate glasses rich in magnesium and iron (Mg-Fe) and iron-nickel sulfides. The carbonaceous materials are similar in texture to primitive organic matter observed in cometary dust but differ in composition – lacking nitrogen and oxygen. Said Matsumoto:

“We propose that the carbonaceous materials formed from cometary organic matter via the evaporation of volatiles, such as nitrogen and oxygen, during the impact-induced heating. This suggests that cometary matter was transported to the near-Earth region from the outer solar system. This organic matter might be the small seeds of life once delivered from space to Earth.”

The carbonaceous material found in the melt splash shows a spongy texture and contains small iron sulfide inclusions. ©Megumi Matsumoto et al.

Looking ahead, the team hopes to examine more Ryugu samples that will provide further insights into how primitive organic materials were delivered to Earth billions of years ago. Similarly, scientists at NASA’s Johnson Space Center recently completed the careful process of removing the samples collected by the OSIRIS-REx mission from their sample container. Analysis of these samples will reveal the composition and history of asteroid Bennu, another NEA that will provide vital information on how our Solar System evolved.

Further Reading: Tohoku University, Science Advances

The post Asteroid Ryugu Contained Bonus Comet Particles appeared first on Universe Today.

Preparations are underway for a third attempted launch of the enormous Starship rocket after the first two test flights both ended in explosions

Through experiments in macaques, scientists have mapped how a range of organs - including the heart, liver and skin - change their interactions during pregnancy, and they expect much of this will also apply in people

The article below in the City Journal by anthropologist Elizabeth Weiss details harmful changes in interpreting the Native American Graves Protection and Repatriation Act (NAGPRA)—an act intended to return human remains and funerary objects to the Native American tribes to which they “belong”. The new interpretation appears to be that any archaeological object that can be claimed by Native Americans, even without convincing DNA or provenance connections, and on the basis of oral tradition alone, can be taken out of museums or hidden away.

I don’t have huge objections to the original act except that human remains should be allowed to be studied by scientists before being returned, and so long as the proper group of Native Americans can be identified. But the NAGPRA has expanded, as Weiss recounts in her report (click to read). The new interpretation is a recipe for the obfuscation of history on the grounds of, well, religion, and involves slippery claims what is “more likely than not”.

Here’s some of Elizabeth’s text:

NAGPRA was enacted to repatriate human remains and certain artifacts to modern tribes with direct ancestral links to past tribes. Descendancy, also referred to as lineal descent and cultural affiliation, was to be determined through a “preponderance of evidence” (a greater than 50 percent chance that the claim is true), using data from geography, kinship studies, biology, archaeology, anthropology, linguistics, folklore, and history. Also considered evidence was oral tradition coming from modern tribes. All evidence could be challenged and was given equal weight.

It’s fair to say that NAGPRA has been generous to Native American tribes by allowing oral tradition to be used as evidence of ancestral ties to the past, since oral tradition contains creation myths, supernatural tales, anachronisms, and miraculous events. Coming from other religions, such materials are usually not considered in legal cases. Thus, retired attorney James W. Springer and I, in our 2020 book Repatriation and Erasing the Past, pointed out that NAGPRA may be violating the Establishment Clause of the First Amendment to the U.S. Constitution: “Congress shall make no law respecting an establishment of religion.” This clause is meant to prevent the federal government from favoring any specific faith; it is charged to treat all religious evidence equally.

Yet, even with the act’s long-standing generosity toward oral tradition, tribal repatriation activists and their allies were unsatisfied with NAGPRA and its terms allowing for the continued research, curation, and display of mostly unaffiliated human remains and artifacts. Nearly all affiliated human remains and related artifacts—by 2020, 91.5 percent of them—have already been repatriated. Critics have focused on the number of materials not yet repatriated, but these consist mainly of unaffiliated materials.

Dissatisfaction among repatriation activists had spurred occasional regulatory changes to NAGPRA. The latest, which went into effect this year, include the deletion of the term “culturally unidentified,” which means that all human remains and artifacts are now vulnerable to repatriation—even discoveries such as the 11,500-year-old Alaskan child named Sunrise Girl, whose DNA couldn’t be matched with DNA from any of the 167 ethnic groups the researchers tested. Sunrise Girl likely represents an individual from a long-gone Beringian tribe.

It would be a crime if “Sunrise Girl”, who represents inhabitants of North America not long after they arrived, were removed from study: click on the link to see what scientists concluded from the DNA of two ancient infants. Further “traditional knowledge,” which is supposed to be weighed in making these decisions, is now malleable!:

The summary of NAGPRA’s latest regulatory revision also states that “museums and Federal agencies must defer to the Native American traditional knowledge of lineal descendants, Indian Tribes, and Native Hawaiian organizations.” Previously, “oral tradition” was given the same weight as scientific and historical evidence; now, it trumps scientific and historical evidence. “Traditional knowledge” was not even mentioned in previous versions of NAGPRA. Native American traditional knowledge is a new term meant to encompass more than just oral tradition. According to the new regulations, Native American traditional knowledge, which is considered “expert opinion,” is defined as “covering a wide variety of information, including, but not limited to, cultural, ecological, linguistic, religious, scientific, societal, spiritual, and technical knowledge.” Further, “Native American traditional knowledge . . . is not required to be developed, sustained, and passed through time”—in other words, it can change at any time. And yet, because traditional knowledge is often “safeguarded or confidential,” its thus cannot be compared with previous decisions based such knowledge—in fact, it cannot be questioned at all.

This is of course all based on the premise that the wishes of Native Americans must be respected simply because they are indigenous people. But surely objects not connected with burial and whose provenance is unknown and can’t be proven, should simply be handed over to scientists for study and then and put in museums. After all, we are not talking about the Elgin Marbles! Unless those items were somehow stolen from Native Americans, what case can be made that they now can be repossessed by them? If you find an arrowhead or a pottery shard, what is the ethical principle that dictates that “traditional knowledge” should have any weight about what happens to the object?

But, as Dr. Weiss notes, this is going to empty out museum exhibits, and for really bizarre reasons:

We can expect bare display cases because some objects will be deemed too “spiritually powerful” to display. AMNH curators have already made similar decisions recently in the renovation of the Northwest Coast Hall. For instance, curators decided not to display a bird bone whistle because Nuxalk elders warned that the whistle could be used as a “summoning tool for supernatural beings.” And Haida tribal members instructed museum staff not to put a headdress on view or even handle the headdress because of the “danger” that they’d encounter—after all, one must “be wary of any object that incorporates human hair.” In other instances, absurd narratives, such as those found in the Northwest Coast Hall, will be taught to children as facts. Children will be told that objects have spirits, that Native Americans came from supernatural animals, and that shamans’ masks contain powers that one should fear.

Are we to cater to superstitions in this way? Are our children now to be subject to the pollution of the “other ways of knowing” trope?

But perhaps the most ludicrous part is this: Weiss’s speculation that contemporary art by Native Americans could be controlled by tribes rather than the artist, a possibility that could be counterproductive to the production of art by Native Americans:

Perhaps most ominously, NAGPRA may eventually extend its reach to art museums. Once all the natural history museum exhibits have been remodeled and the tribes have taken back most of the interesting objects, Native American repatriation activists will likely not be satisfied. New targets are sure to include art purchased from contemporary Native American artists. In a recent NAGPRA information session about the new regulations, art museum curators were told to consult with tribes over the display of art created by contemporary Native American artists that had been recently purchased for display. This may lead to art museum curators deciding to avoid NAGPRA hassles by ceasing to buy or display the works of Native American artists. This will harm the artists most; the museums will find other works.

The basis for these changes are obvious: a desire to cater to those perceived as underdogs, regardless of the strength of their claims. But this catering isn’t harmless, for it obfuscates our understanding of the history of North America.

Update: To see some of the results, click on this article, which a reader just sent me. I’ve used an archived link, so it’s free. I don’t have time to summarize it, but note that the claim that things like darts and canoes are “sacred items” doesn’t carry much water.

Supernovae are relatively rare. It might not seem like it, but that’s because they’re so bright we can see them in other galaxies a great distance away. In fact, in 2022, astronomers spotted a supernova over 10 billion light-years away.

Any time astronomers spot a supernova, it’s an opportunity to learn more about these rare, cataclysmic explosions. It’s especially valuable if astronomers can get a good look at the progenitor star before it explodes.

We know what types of stars explode as core-collapse supernovae: massive ones. But we don’t know which star will explode when, so we don’t know where to look to see the progenitor. The authors of new research put this succinctly when they write, “Obtaining spectroscopic observations of the progenitors of core-collapse supernovae is often unfeasible due to an inherent lack of knowledge as to which stars will go supernova and when they will explode.”

That quote comes from a new research letter titled “Spectroscopic observations of progenitor activity 100 days before a Type Ibn supernova.” The letter has been submitted to the journal Astronomy and Astrophysics and is currently in pre-press. The lead author is Seán Brennan from the Department of Astronomy at Stockholm University.

Astronomers keep learning more about supernovae progenitors. They’re finding that supernova progenitors can exhibit powerful outbursts in the weeks, months, or even years before they explode. Astronomers keep getting better and better tools to spot these outbursts, and sometimes they get lucky.

In April of 2023, a massive star exploded in NGC 4388, a spiral galaxy about 57 million light-years away. The Zwicky Transient Facility (ZTF) spotted it, and the supernova is called SN 2023fyq. SN 2023fyq is a rare type of supernova called a Type Ibn. They show a lack of hydrogen lines and narrow He I emission lines in their spectra. Astronomers think that these characteristics come from the SN interacting with hydrogen-poor, helium-rich circumstellar material (CSM.)

Astronomers only know of a few of these types of SN, so their progenitors are poorly understood. Prior to its explosion, the ZTF also spotted the precursor activity, providing a window into these mysterious progenitors.

This figure shows the supernova and its location in NGC 3288. Image Credit: Brennan et al. 2024

“This Letter presents spectral and photometric observations of the progenitor of a Type Ibn SN several months before core-collapse, as well as SN 2023fyq itself,” the researchers write. The observations come from multiple telescopes and observatories, including the Keck 10m telescope, the Palomar 200-inch telescope, and the Gemini North 8m telescope.

The researchers found that the progenitor’s luminosity increased exponentially during the 150 days leading up to the explosion. They also found that the radius of the photosphere remained almost constant during the same time. The pre-supernova spectra also “reveal a complex evolving He I profile.”

This chart from the study shows the spectral observations of SN 2023fyq and its progenitor. The progenitor’s observations are on the top, and the SN’s observations are on the bottom. Each line represents a different set of observations, with their times written at their ends. The red line shows observations of SN 2010al, a Type Ibn SN that matches well with SN 2023fyz. He I areas are labelled because the researchers pointed out that there was a complex, evolving He I profile. Image Credit: Brennan et al. 2024

The He I profile could be a clue to some of the progenitor star’s activity. There are similar He I emissions in both the progenitor and the SN. “This would mean that the asymmetric material responsible for this emission was not destroyed in the SN explosion,” the authors explain. “SN ejecta interacting with asymmetric circumstellar material (CSM) has been used to explain irregular emission line profiles.” We’re getting deep into the weeds here, but it’s significant. “… SN 2023fyq provides the first clear spectroscopic evidence of asymmetric structure prior to core-collapse.”

It’s possible that some of the features in the spectroscopy are caused by circumstellar material (CSM). “Some mechanisms cause the progenitor to be surrounded by a dense CSM,” the authors explain, “and may lead to shock dissipation and emission of radiation in the optically thick CSM.” In that case, diffusion could explain the light curve’s general rise. “This also explains the roughly constant radius and the slowly rising effective temperature,” they write.

“These observations of SN 2023fyq and the final moments of the progenitor highlight that the progenitors to CCSNe can undergo some extreme instabilities shortly before their final demise,” the authors write.

It shouldn’t surprise anyone that a progenitor exhibited some extreme instabilities before exploding as a supernova. It would be very strange if a massive star suddenly exploded with no lead-up. Only massive stars explode as supernovae, and it happens when the star’s outward fusion pressure is insufficient to counteract the star’s own gravity. The star collapses in on itself and explodes. This is a cataclysmic event, and there are bound to be shock waves travelling through the star, as well as other interactions. There are bound to be “extreme instabilities,” as the authors call them.

But what exactly does this tell us?

Artist view of a supernova explosion. Credit: NASA

This is just a research letter, and the authors are presenting their results to the astronomical community. They can show the unusual activity evident in spectroscopic observations, but they can’t tell us exactly what it means yet. But it does show that we’re able to spot supernova progenitors, a huge step in understanding core-collapse supernovae.

“Progenitor analysis typically occurs after the star has been destroyed by searching through archival images and measuring the photometric properties of the assumed progenitor,” the researchers write in their letter. “Although this area of transient astronomy is in its infancy, the repercussions of detecting precursor activity are immense, highlighting that the progenitor is not in an equilibrium state and may
not be represented well by standard stellar evolutionary models.”

We’re looking at an SN progenitor when we look at Betelgeuse; astronomers just don’t know how long it’ll be until the star explodes. But it appears to have belched plasma that created a dust cloud that briefly dimmed the star a couple of years ago. Is that behaviour indicative of how other progenitors behave?

Astronomers need to observe more supernova progenitors of different types before they can answer their questions. Once they have more data, they’ll build models of how supernova progenitors behave leading up to the explosion. Then, they can observe even more SN and test that data against their models. Then, they’ll improve their models some more.

Eventually, they’ll have answers.

The post Giant Star Seen 150 Days Before it Exploded as a Supernova appeared first on Universe Today.

Although the exact nature of dark matter continues to elude astronomers, we have gained some understanding of its general physical properties. We know how it clusters around galaxies, how it makes up much of the matter in the Universe, and even how it can interact with itself. Now a new study looks at just how fast dark matter can move.

The study focuses on an effect known as dynamical friction. The term is a bit of a misnomer since it isn’t the kind of friction you see between two objects sliding against each other. A better term for the effect might be gravitational drag. It was first studied by Subrahmanyan Chandrasekhar in 1943, and it’s caused by the gravitational interactions of a diffuse body.

Imagine a massive star moving through a cluster of red dwarf stars. Even though none of the stars are likely to collide, the gravitational interactions between them will affect stellar motions. The massive star will slow down as it leaves the cluster thanks to the gravitational tug of the red dwarf stars. On the other hand, the red dwarf stars will speed up a bit as they are dragged slightly toward the massive star. If you track the change in speed of the stars in the cluster, you can determine how fast the cluster was moving before the collision.

The galactic effects of dynamical friction. Credit: Kipper, et al

The same effect can occur between matter and dark matter. The presence of dark matter affects the motion of stars in the galaxy, and thanks to dynamical friction this distorts the shape of the galaxy. By mapping how the galaxy is distorted the team can calculate the motion of dark matter near the galaxy. So the team focused on finding distorted galaxies that aren’t part of a dense galactic cluster. Since the galaxies are fairly isolated, the distortion must occur because of dark matter.

The authors then compared the shape of these distorted galaxies to N-body simulations to map the motion of dark matter. One of the concerns they had was that the uncertainty in the data would be too large to make any meaningful constraints on dark matter. The team showed that for available samples, the data scatter is only about 10%. This means it is precise enough to apply to nearby galaxies. For example, detailed Gaia observations of the Large Magellanic Cloud should allow astronomers to get a handle on dark matter speeds there.

This approach gives astronomers one more tool for the study of dark matter. As future observations allow us to pin down the properties of dark matter, we may be able to determine what dark matter really is.

Reference: Kipper, Rain, et al. “Back to the present: A general treatment for the tidal field from the wake of dynamical friction.” Astronomy & Astrophysics 680 (2023): A91.

The post Dark Matter Might Help Explain How Supermassive Black Holes Can Merge appeared first on Universe Today.

Researchers demonstrated a 300 GHz-band wireless link that was able to transmit data over a single channel at a rate of 240 gigabits per second. The wireless communication system employs signal generators based on lasers that have ultra-low phase noise in the sub-terahertz band. This rate is the highest so far reported at these frequencies and is a substantial step forward in 300 GHz-band communications for 6G networks.

Researchers demonstrated a 300 GHz-band wireless link that was able to transmit data over a single channel at a rate of 240 gigabits per second. The wireless communication system employs signal generators based on lasers that have ultra-low phase noise in the sub-terahertz band. This rate is the highest so far reported at these frequencies and is a substantial step forward in 300 GHz-band communications for 6G networks.

A collaborative group of researchers has potentially developed a means of controlling spin waves by creating a hexagonal pattern of copper disks on a magnetic insulator. The breakthrough is expected to lead to greater efficiency and miniaturization of communication devices in fields such as artificial intelligence and automation technology.

A collaborative group of researchers has potentially developed a means of controlling spin waves by creating a hexagonal pattern of copper disks on a magnetic insulator. The breakthrough is expected to lead to greater efficiency and miniaturization of communication devices in fields such as artificial intelligence and automation technology.

Theoretical predictions have been confirmed with the discovery of an outflow of molecular gas from a quasar when the Universe was less than a billion years old.

Researchers recently succeeded in producing a highly durable time crystal that lived millions of times longer than could be shown in previous experiments. By doing so, they have corroborated an extremely interesting phenomenon that Nobel Prize laureate Frank Wilczek postulated around ten years ago and which had already found its way into science fiction movies.

Researchers have developed a transmissive thin scintillator using perovskite nanocrystals, designed for real-time tracking and counting of single protons. The exceptional sensitivity is attributed to biexcitonic radiative emission generated through proton-induced upconversion and impact ionization.

Researchers have gained new insights into the development of the light-induced ferroelectric state in SrTiO3. They exposed the material to mid-infrared and terahertz frequency laser pulses and found that the fluctuations of its atomic positions are reduced under these conditions. This may explain why the dipolar structure is more ordered than in equilibrium and why the laser pulses induce a ferroelectric state in the material.

A team of researchers mapped out how flecks of 2D materials move in liquid -- knowledge that could help scientists assemble macroscopic-scale materials with the same useful properties as their 2D counterparts.

Computer scientists found that email notifications to update passwords potentially yielded diminishing returns after three messages. They also found that a prompt to update passwords while users were trying to log in was effective for those who had ignored email reminders. Researchers also found that users whose jobs didn't require much computer use struggled the most with the update.

Scientists have developed a new approach to machine learning -- a form of artificial intelligence -- to identify drugs that help minimize harmful scarring after a heart attack or other injuries.