"When beggars die, there are no comets seen;
The heavens themselves blaze forth the death of princes."

— William Shakespeare
Julius Cæsar

Astronomy

Ep. 713: Solar System Volcanoes – An Update from LPSC 2024

Astronomy Cast - Mon, 03/25/2024 - 5:00pm

Last week was one of the most exciting meetings we’ve seen from the Lunar and Planetary Science Conference, with hundreds of announcements and discoveries from various missions. One theme kept coming up, the Solar System is more volcanically active than we thought. Today, we’ll explore volcanism on other worlds.

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Categories: Astronomy

Chasing the Eclipse from the Air

Sky & Telescope Magazine - Mon, 03/25/2024 - 4:30pm

A solar-imaging instrument will fly on a high-altitude aircraft to explore infrared emission from the Sun’s corona.

The post Chasing the Eclipse from the Air appeared first on Sky & Telescope.

Categories: Astronomy

Brown Dwarf Pairs Drift Apart in Old Age

Universe Today - Mon, 03/25/2024 - 4:09pm

The only thing worse than drifting through space for an eternity is doing it alone. Observations with the Hubble Space Telescope show that brown dwarfs that once had companions suffer that fate. Binary brown dwarfs that were once bound to each other tend to drift apart as time passes.

Brown dwarfs are one of Nature’s genre-busters. They refuse to be pigeonholed into our definitions. They’re neither stars nor planets and are sometimes referred to as failed stars. They gathered too much mass to be called planets but not enough to be called stars. They live in a kind of twilight zone, where they go about their business fusing only deuterium. This fusion is enough to emit some light and warmth but nothing that rivals an actual main sequence star.

Brown dwarfs are too big to be planets but not quite massive enough to be stars. Credit: NASA/JPL-Caltech

Brown dwarfs are not necessarily brown in colour. Their name comes from their size. They’re in between white dwarf stars and “dark” planets, if that makes sense. Brown dwarfs fade over time as they deplete their deuterium. The warmest ones are red or orange, and the cooler ones are magenta or even black to our eyes. Astronomers think brown dwarfs will cool down forever.

Most stars are in binary pairs, and brown dwarfs are no exception. Up to 85% of stars in the Milky Way are in binary pairs, according to some research. But the Hubble shows that when it comes to brown dwarfs, divorce is more common than in Hollywood.

In a survey of stars in our solar neighbourhood, the HST didn’t find any binary brown dwarfs with widely separated companions. That implies that brown dwarfs can’t maintain their binary relationships, probably because they’re simply not massive enough.

“This is the best observational evidence to date that brown dwarf pairs drift apart over time,” said Clémence Fontanive, the lead author of a new paper. “We could not have done this kind of survey and confirmed earlier models without Hubble’s sharp vision and sensitivity.”

The new paper is in the Monthly Notices of the Royal Astronomical Society. Its title is “An HST survey of 33 T8 to Y1 brown dwarfs: NIR photometry and multiplicity of the coldest isolated objects.” The lead author is Clémence Fontanive from the Trottier Institute for Research on Exoplanets, Université de Montréal, Canada. Brown dwarfs occupy spectral types M, L, T, and Y, and the numbers in the title are sub-types.

“Our survey confirms that widely separated companions are extremely rare among the lowest-mass and coldest isolated brown dwarfs, even though binary brown dwarfs are observed at younger ages. This suggests that such systems do not survive over time,” said lead author Fontanive.

The researchers worked with a set of 33 nearby ultracool brown dwarfs, a sample large enough to be statistically significant. The survey was designed to be deeply sensitive to low-mass objects that could be companions. Though the survey unearthed some potential companions for some of the brown dwarfs, further analysis showed they’re background objects.

The fact that they detected no binary companions allowed the researchers to “place stringent upper limits on the occurrence of binary companions,” according to the paper. But the lack of detection also means they can’t place any constraints or limits on the binary orbital separation or mass ratio distributions of this population.

This survey only examined older, dimmer brown dwarfs. Younger brown dwarfs can still have their binary partners. Studies of younger brown dwarfs show that around eight percent of them have binary partners. In fact, the younger the brown dwarf, the more likely it is to have a binary partner. “These findings marginally confirm the idea that the decrease in binary frequencies with later type observed across the stellar and substellar regimes for the field population might continue throughout the substellar mass range down to the very lowest masses, as illustrated in Fig. 12,” the authors explain.

This is Figure 12 from the study, and it illustrates the rate of brown dwarf binary companions as brown dwarfs age. The binary frequency is shown on the y-axis, and the spectral type, which relates to age, is on the x-axis. Each mark inside the graph plots the results of a study of brown dwarf companions, including this one in pink. The graph clearly shows that younger brown dwarfs have more binary companions than aged brown dwarfs. Image Credit: Fontanive et al. 2024.

In a press release, lead author Fontanive explained why brown dwarfs lose their binary partners over time.

“Our Hubble survey offers direct evidence that these binaries that we observe when they’re young are unlikely to survive to old ages; they’re likely going to get disrupted. When they’re young, they’re part of a molecular cloud, and then, as they age, the cloud disperses. As that happens, things start moving around, and stars pass by each other. Because brown dwarfs are so light, the gravitational hold tying wide binary pairs is very weak, and bypassing stars can easily tear these binaries apart,” said Fontanive.

The authors point out that there’s an inevitable weakness in their results. Since brown dwarfs are so small and dim, the usual methods of detecting companions don’t work. Astronomers rely on the transit method and the radial velocity method to detect companion objects, whether planets orbiting stars or other objects in relationships with one another.

But their inherent dimness makes detecting transits very difficult. Their inherent low masses likewise make the radial velocity ineffective. That leaves them with the direct optical detection method the researchers in this study relied on.

There could be a better way.

Astrometry might provide a more viable alternative approach to search for companions to faint brown dwarfs, although very little work has been carried out on this side, and no systems have been reported this way so far,” the authors write in the conclusion.

When it comes to astrometry, the ESA’s Gaia spacecraft is the standard-bearer. It has the power to detect Jupiter-mass companions when they’re orbiting main sequence stars, but detecting binary brown dwarfs is still difficult, even for Gaia. Gaia has detected many brown dwarfs, but for now, it’s up to direct imaging to detect brown dwarf binary pairs. In this study, direct imaging found no widely separated binary companions despite the HST’s effectiveness.

“With an excellent sensitivity and completeness to companions on wide orbital separations, our survey robustly confirms that wide companions are extremely rare in the Galactic field around the lowest mass systems,” the authors write. Any companions would need to be inside the 1 to 5 AU limit of this work.

“Our results, with no detection of wide companions out of 33 observed objects, reinforce the idea that the widely separated binaries with very low-mass primaries identified in young associations have no counterparts among isolated objects in the Solar neighbourhood,” the authors conclude.

The post Brown Dwarf Pairs Drift Apart in Old Age appeared first on Universe Today.

Categories: Astronomy

NASA is holding a total eclipse 2024 briefing tomorrow. Here's how to watch it live

Space.com - Mon, 03/25/2024 - 3:59pm
Watch NASA's total eclipse 2024 briefing live and learn about the scientific and transportation plans for the eclipse.
Categories: Astronomy

Dwarf Galaxies Could be the Key to Explaining Dark Matter

Universe Today - Mon, 03/25/2024 - 3:35pm

If you have a view of the southern celestial sky, on a clear night you might see two clear smudges of light set off a bit from the great arch of the Milky Way. They are the Large and Small Magellanic Clouds, and they are the most visible of the dwarf galaxies. Dwarf galaxies are small galaxies that typically cluster around larger ones. The Milky Way, for example, has nearly two dozen dwarf galaxies. Because of their small size, they can be more significantly affected by dark matter. Their formation may even have been triggered by the distribution of dark matter. So they can be an excellent way to study this mysterious unseen material.

In a recent study, a team looked at dwarf galaxies to see exactly what they would reveal about dark matter. Specifically, they were interested in how dark matter might interact with itself. One idea about dark matter particles is that when they collide with each other they could emit gamma-ray light. This would mean that the central regions of galaxies should show evidence of gamma radiation without a clear astrophysical source. There have been some studies looking for gamma rays within our own galaxy, but the results have been inconclusive.

This new study focused on dwarf galaxies because they are smaller and therefore less likely to obscure gamma-ray light from colliding dark matter. There are also plenty of dwarf galaxies within our local group. Using 14 years of archival data from the Fermi-Large Area Telescope (LAT), the team looked at 50 dwarf galaxies. Overall they didn’t find strong evidence of gamma-ray emissions from any of the galaxies, but in 7 of them they found a small statistical excess at around 2? – 3?. To be definitive we’d like to see it at a level of 5?, so this result is far from conclusive. But if we take the energy levels of the excess at face value, it would put the mass of dark matter particles around 30 – 50 GeV or 150 ? 230 GeV, depending on the way dark matter might decay. By comparison, protons have a mass of about 1 GeV.

So once again a study of dark matter fails to discover the elusive particles. But as with earlier studies, this research narrows down what dark matter might be. Specifically, the study rules out certain mass ranges for dark matter more than ever before. It’s yet another small step toward solving the mystery of dark matter.

Reference: McDaniel, Alex, et al. “Legacy analysis of dark matter annihilation from the Milky Way dwarf spheroidal galaxies with 14 years of Fermi-LAT data.” Physical Review D 109.6 (2024): 063024.

The post Dwarf Galaxies Could be the Key to Explaining Dark Matter appeared first on Universe Today.

Categories: Astronomy

SpaceX launches 23 Starlink satellites from Florida

Space.com - Mon, 03/25/2024 - 3:12pm
A SpaceX Falcon 9 rocket launched 23 more of the company's Starlink broadband satellites to orbit this evening (March 25).
Categories: Astronomy

Cement, Steel—And Pasta—Are About to Get Greener

Scientific American.com - Mon, 03/25/2024 - 2:30pm

Factories that produce everything from aluminum to pasta are receiving a combined total of billions of dollars in government funding to reduce greenhouse gas emissions from industry

Categories: Astronomy

Intuitive Machines' historic private moon moon mission comes to an end

Space.com - Mon, 03/25/2024 - 2:00pm
Intuitive Machines' Odysseus moon lander has failed to send out a wakeup signal, confirming that its pioneering mission is over.
Categories: Astronomy

An Asteroid Found Sharing the Orbit of Mars

Universe Today - Mon, 03/25/2024 - 1:50pm

Astronomers discovered another asteroid sharing Mars’ orbit. These types of asteroids are called trojans, and they orbit in two clumps, one ahead of and one behind the planet. But the origins of the Mars trojans are unclear.

Can this new discovery help explain where they came from?

There are now 14 known Mars Trojans and the name of the newest one is 2023 FW14. They’re in two groups, one 60 degrees ahead and one 60 degrees behind Mars. These are the Lagrange 4 and Lagrange 5 points.

Most of the Mars trojans are at the L5 point, and this newly discovered one is the second one found at the L4 point.

New research published in the journal Astronomy and Astrophysics presents the discovery. Its title is “Dynamics of 2023 FW14, the second L4 Mars trojan, and a physical characterization using the 10.4 m Gran Telescopio Canarias.” The lead author is Raul de la Fuente Marcos from the Earth Physics and Astrophysics Department at the Universidad Complutense de Madrid.

Scientists aren’t certain where the Mars trojans came from. Other trojans like the Jupiter trojans may have been captured by Jupiter in the Solar System’s early years. Or Jupiter may have captured them later when it migrated.

But Mars is a much less massive planet, and astronomers aren’t certain if Mars can capture trojans the same way Jupiter does. The Mars trojans could be as old as the Jupiter trojans, but some evidence suggests otherwise. The dozen or more trojans at the Mars L5 point seem to be a family from the same collision. The family is called Eureka, and their spectra indicate an olivine-rich composition.

Olivine is relatively rare in the main asteroid belt. That’s led some researchers to suggest that the L5 Mars trojans are debris from an ancient impact between Mars, where olivine is common, and a planetesimal.

The two L4 Mars trojans are different. They don’t have the same spectra as the L5 trojans, but the pair do show some similarities in their spectra, so a common origin for these two is a possibility.

In this paper, the researchers set out to determine 2023 FW14’s origins. They used the Gran Telescopio Canarias for their work. It’s a 10.4-meter telescope in Spain’s Canary Islands with an attached instrument called the OSIRIS camera spectrograph.

2023 FW14’s spectrum places it in the same class as an Xc-type asteroid. The X-type name contains several different types of asteroids with similar spectra but probably with different compositions. Xc-types are a sub-class of the X-types that are intermediate between C-type asteroids, the most common type of asteroid in the Solar System, and the uncommon K-type asteroids.

This graph from the research shows the spectrum of 2023 FW14 and several spectra of the other known L4 Mars Trojan (121514) 1999 UJ7. Orange shows 2023 FW14, with the red line representing the best asteroid taxonomical match, the Xc-type. Teal, blue, and green show different published spectra of 1999 UJ7. The gray area fills the entire domain between the mean B-type and D-type classes of asteroids. Image Credit: Marcos et al. 2024.

The researchers also used N-body simulations to try to understand the new asteroid’s resonance with Mars. Trojans follow what are known as tadpole orbits. Tadpole orbits are influenced by Earth’s gravity, which causes objects to librate or accelerate or decelerate alternately.

Tadpole orbits are complex. Asteroids on these orbits exchange large amounts of energy and angular momentum with a planet moving in a circular orbit. Tadpole loops are made of multiple overlapping epicyclic loops.

This video illustrates the tadpole orbit followed by an asteroid in Jupiter’s L4, not Mars’ L4, but the concept is the same.

2023 FW14 has a higher orbital eccentricity and lower inclination than Mars’ other L4 trojan. This means that it occupies an unstable region and orbits at the whim of several different resonances. That instability means that in a few million years, it’ll likely be ejected.

The researchers calculated its size as approximately 318 metres (+493/-199.) That makes it one of the smallest known trojans so far.

As for its origins, the authors say that there are two possibilities.

Its long-term behaviour, including its past, suggests that it was captured from the Near Earth Asteroid (NEA) population of Mars-crossing asteroids. But it could be a fragment of another trojan, as well, one that is so far undiscovered, or one that is no longer a trojan.

Spectral data suggests something else. Both of the L4 asteroids appear to be more primitive than Mars’ L5 trojans. 2023 FW14’s spectrum also supports the idea that it’s a captured Mars-crossing NEA. However, that data isn’t as clear, according to the authors, and can’t be used to rule out the other hypothesis, which is that the asteroid formed in situ. “Although incomplete, the data support the interpretation of 2023 FW14 as an interloper captured from the Mars-crossing NEA population, but they cannot be used to reject the competing hypothesis that 2023 FW14 was produced in situ,” they write.

Whatever its origins are, the researchers calculate that 2023 FW14 has about 10 million years before it’s ejected from its trojan orbit. It’s a temporary trojan, and this discovery could prove that Mars trojans can be temporarily captured, something that so far has been unproven.

The post An Asteroid Found Sharing the Orbit of Mars appeared first on Universe Today.

Categories: Astronomy

Fake solar eclipse glasses are everywhere ahead of the total solar eclipse. Here's how to check yours are safe

Space.com - Mon, 03/25/2024 - 1:14pm
With two weeks until April 8's total solar eclipse, the American Astronomical Society is warning buyers about unsafe and counterfeit solar glasses.
Categories: Astronomy

Wild Birds Gesture ‘After You’ to Insist Their Mate Go First

Scientific American.com - Mon, 03/25/2024 - 12:45pm

Like humans, these small Japanese birds communicate abstract concepts with gestures

Categories: Astronomy

Wildfire smoke may be deadliest effect of climate change in US

New Scientist Space - Cosmology - Mon, 03/25/2024 - 12:00pm
Smoke from wildfires made worse by climate change is set to cause thousands of additional deaths each year in the US
Categories: Astronomy

Wildfire smoke may be deadliest effect of climate change in US

New Scientist Space - Space Headlines - Mon, 03/25/2024 - 12:00pm
Smoke from wildfires made worse by climate change is set to cause thousands of additional deaths each year in the US
Categories: Astronomy

'Star Wars' fan-favorite Sith returns in 'Darth Maul: Black, White & Red'

Space.com - Mon, 03/25/2024 - 12:00pm
A preview of Marvel Comics' upcoming miniseries, "Darth Maul: Black, White & Red"
Categories: Astronomy

The unexpected reasons why human childhood is extraordinarily long

New Scientist Space - Cosmology - Mon, 03/25/2024 - 12:00pm
Why childhood is so protracted has long been mysterious, now a spate of archaeological discoveries suggest an intriguing explanation
Categories: Astronomy

3 spaceflyers arrive at the ISS aboard Russian Soyuz spacecraft

Space.com - Mon, 03/25/2024 - 11:30am
A Russian Soyuz spacecraft delivered three spaceflyers, including one NASA astronaut, to the International Space Station today (March 23).
Categories: Astronomy

Martin MacInnes: 'Science fiction can be many different things'

New Scientist Space - Cosmology - Mon, 03/25/2024 - 11:30am
The author of In Ascension, the latest pick for the New Scientist Book Club, on why he wrote his novel, cultivating a sense of wonder and the role of fiction in the world today
Categories: Astronomy

Hubble Views a Galaxy Under Pressure

NASA Image of the Day - Mon, 03/25/2024 - 11:30am
This NASA/ESA Hubble Space Telescope image shows LEDA 42160, a galaxy about 52 million light-years from Earth in the constellation Virgo. The dwarf galaxy is one of many forcing its way through the comparatively dense gas in the massive Virgo cluster of galaxies. The pressure exerted by this intergalactic gas, known as ram pressure, has dramatic effects on star formation in LEDA 42160.
Categories: Astronomy, NASA

Dust clouds from the Sahara are reaching Europe more frequently

New Scientist Space - Cosmology - Mon, 03/25/2024 - 11:00am
Changes in wind patterns and desertification may be increasing the amount of dust from the Sahara desert blown over western Europe and the frequency of these events
Categories: Astronomy

Opposites attract? Not in new experiment that finds loophole in fundamental rule of physics

Space.com - Mon, 03/25/2024 - 10:59am
Like-charged objects were found to clump together while opposites repelled because of the newly discovered "electrosolvation force."
Categories: Astronomy