Tag: astronomy

More surprises from the Wolf-Rayet star numbered 104 and known for its pinwheel structure

2:03 pm

Keck infrared data of WR104

Among astronomers who study such things, Wolf-Rayet 104 is one of the most well known OB massive stars in their catalog, with the infrared picture to the right illustrating why. The star is actually a binary of massive stars, orbiting each other every eight months. Both produce strong winds, and the collision of those winds results in a glorious pinwheel structure that glows in the infrared.

Such stars are also believed to be major candidates to go supernova and in doing so produce a powerful gamma ray burst (GRB) that would shoot out from the star’s poles. As the orientation of this pinwheel suggests we are looking down into the pole of the system, this star system was actually considered a potentially minor threat to Earth. Located about 8,400 light years away, this is far enough away to mitigate the power of the GRB, but not eliminate entirely its ability to damage the Earth’s atmosphere.

New research now suggests however that despite the orientation of the pinwheel, face-on, the plane of the binary star system is actually tilted 30 to 40 degrees to our line of sight. The press release asks the new questions these results raise:

While a relief for those worried about a nearby GRB pointed right at us, this represents a real curveball. How can the dust spiral and the orbit be tilted so much to each other? Are there more physics that needs to be considered when modelling the formation of the dust plume?

You can read the paper here. It is a quite refreshing read, not just because of its relatively plain language lacking jargon, but because of its willingness to list at great length the uncertainties of the data.

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Webb captures infrared images of five exoplanets orbiting two different stars

10:17 am

Four gas giants in infrared
Click for original image.

Using the Webb Space Telescope, astronomers have taken two different direct false-color infrared images of exoplanets orbiting the stars HR 8799 (130 light years away) and 51 Eridani (97 light years away.

The image of the four gas giants orbiting HR 8799 is to the right, cropped, reduced, and slightly enhanced to post here. From the caption:

The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light.

The Webb false color infrared picture taken of one of the exoplanets orbiting the star 51 Eridani is also at the link, showing “a cool, young exoplanet that orbits 890 million miles from its star, similar to Saturn’s orbit in our solar system.”

The data from the HR 8799 image suggests these gas giants have a lot of carbon dioxide gas, and thus might be growing by pulling in material from the star’s accretion disk.

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Astronomers discover 128 more moons around Saturn

9:01 am

Using a ground-based telescope, astronomers have now identified 128 new moons circling Saturn, bringing its moon count to 274, more than the total moons around all the other planets in the solar system combined.

Edward Ashton at Academia Sinica in Taipei, Taiwan, and his colleagues found the new moons with the Canada-France-Hawaii Telescope, revealing dozens that have previously evaded astronomers. They took hours of images of Saturn, adjusted them for the planet’s movement through the sky and stacked them on top of each other to reveal objects that would otherwise be too dim to see.

All the new moons are between 2 and 4 kilometres in diameter and are likely to have been formed hundreds of millions or even billions of years ago in collisions between larger moons, says Ashton.

That Saturn has so many moons should surprise no one. Saturn actually has possibly millions, maybe even billions, of moons, if you count every particle in its rings. In fact, the gas giant poses a problem for astronomers in defining what a moon actually is. How small must an object be before you stop calling it a moon?

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Astronomers have discovered four sub-Earth-sized exoplanets orbiting Barnard’s Star

10:44 am

Based on data from several ground-based telescopes, astronomers now believe that Barnard’s Star, the nearest single star to our Sun at a distance of about six light years away, has a solar system of at least four sub-Earth-sized planets.

After rigorously calibrating and analyzing data taken during 112 nights over a period of three years, the team found solid evidence for three exoplanets around Barnard’s Star, two of which were previously classified as candidates. The team also combined data from MAROON-X with data from a 2024 study done with the ESPRESSO instrument at the European Southern Observatory’s Very Large Telescope in Chile to confirm the existence of a fourth planet, elevating it as well from candidate to bona fide exoplanet.

You can read the paper here. The scientists estimate the minimum masses of these exoplanets to range from 19% to 34% that of the Earth, with their maximum mass not exceeding 57% of the Earth. All are believed to be rocky planets orbiting just inside the star’s habitable zone.

Astronomers have been trying to detect exoplanets around Barnard’s Star for more a century. Several previous “discoveries” were later retracted. This result however appears somewhat firm though of course there are a lot of uncertainties in the result.

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A galactic ball and spiral interact

9:55 am

A galactic ball and spiral interact
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a study of the star populations in these two interacting galaxies. From the caption:

Arp 105 is a dazzling ongoing merger between an elliptical galaxy and a spiral galaxy drawn together by gravity, characterized by a long, drawn out tidal tail of stars and gas more than 362,000 light-years long. The immense tail, which extends beyond this image from NASA’s Hubble Space Telescope, was pulled from the two galaxies by their gravitational interactions and is embedded with star clusters and dwarf galaxies.

The three blue objects on the outskirts of both galaxies are thought to be active star-forming regions. Whether all three are part of this collision is unclear, as the object on the lower right might simply be a foreground object based on the available data.

What makes this galactic pair so intriguing is that the two galaxies are so different with very different theorized histories. Elliptical galaxies (“the ball”) are thought to be very old, the result of the long term evolution of spirals. You would therefore not think an elliptical would normally interact with a spiral, as their ages are likely so dissimilar.

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Webb captures infrared view of a baby binary star system and its bi-polar jets

9:41 am

A baby binary in formation
Click for original image.

Cool image time! The infrared false-color picture to the right, reduced and sharpened to post here, was released today by the science team of the Webb Space Telescope. It shows the bi-polar jets spewing out from a newly formed binary of two very young stars as their interact during their formation process.

The two protostars responsible for this scene are at the center of the hourglass shape, in an opaque horizontal disk of cold gas and dust that fits within a single pixel. Much farther out, above and below the flattened disk where dust is thinner, the bright light from the stars shines through the gas and dust, forming large semi-transparent orange cones.

It’s equally important to notice where the stars’ light is blocked — look for the exceptionally dark, wide V-shapes offset by 90 degrees from the orange cones. These areas may look like there is no material, but it’s actually where the surrounding dust is the densest, and little starlight penetrates it. If you look carefully at these areas, Webb’s sensitive NIRCam (Near-Infrared Camera) has picked up distant stars as muted orange pinpoints behind this dust. Where the view is free of obscuring dust, stars shine brightly in white and blue.

To put it more simply, the accretion disk for the binary system lies at right angles to the much larger jets. The rotation of that disk as well as the stars causes those jets to flow up and down from the poles, with the existence of two stars producing the complex patterns in those jets.

As this image was focused mostly on studying the upper jet, it does not show the entire lower jet, which extends beyond the lower border.

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Is a supermassive black hole is hidden in the Large Magellanic Cloud?

11:45 am

Based on the motions of a number of runaway stars on the edge of the Milky Way that are moving so fast they will leave the galaxy, astronomers believe that many were accelerated not by the galaxy’s own central supermassive black hole but a previously undetected supermassive black hole at the center of the Large Magellanic Cloud, one of the Milky Ways nearby dwarf galaxies.

To make this discovery, researchers traced the paths with ultra-fine precision of 21 stars on the outskirts of the Milky Way. These stars are traveling so fast that they will escape the gravitational clutches of the Milky Way or any nearby galaxy. Astronomers refer to these as “hypervelocity” stars.

Similar to how forensic experts recreate the origin of a bullet based on its trajectory, researchers determined where these hypervelocity stars come from. They found that about half are linked to the supermassive black hole at the center of the Milky Way. However, the other half originated from somewhere else: a previously-unknown giant black hole in the Large Magellanic Cloud (LMC).

You can read the paper here [pdf]. This result was made possible by the very precise location and velocity data of over a billion stars measured by Europe’s Gaia satellite.

Based on the available data, the scientists estimate (with great uncertainty) the mass of this supermassive black hole, which the scientists have dubbed LMC* (pronounced “LMC star”), to be about 600,000 times the mass of the Sun, quite big but significantly less than the mass of the Milky Way’s central black hole, Sagittarius A* (pronounced “A-star”), which is estimated to be about 4.3 million times the mass of the Sun.

The mystery to solve now is why this super massive black hole is so quiet. It has literally emitted no obvious energy in any wavelength in the past seven decades, since ground- and space-based telescopes went into operation capable of detecting such emissions. Even the relatively inactive supermassive black hole at the Milky Way’s center, Sagittarius A* (pronounced “A-star”) emits distinct radio energy that the first radio telescopes were able to detect almost immediately.

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Scientists: X-rays from the Helix Nebula caused by the destruction of a planet

10:12 am

A composite image of the Helix Nebula
A composite image of the Helix Nebula, combining data
from multiple ground- and space-based telescopes.
Click for original image.

Using data collected by multiple ground-bases and space telescopes over decades, scientists now think the previously unexplained high energy X-rays coming from the white dwarf star at the center of the Helix Nebula are caused by the destruction of a Jupiter-sized exoplanet.

The besieged planet could have initially been a considerable distance from the white dwarf but then migrated inwards by interacting with the gravity of other planets in the system. Once it approached close enough to the white dwarf, the gravity of the star would have partially or completely torn the planet apart. “The mysterious signal we’ve been seeing could be caused by the debris from the shattered planet falling onto the white dwarf’s surface, and being heated to glow in X-rays,” said co-author Martin Guerrero of The Institute of Astrophysics of Andalusia in Spain. “If confirmed, this would be the first case of a planet seen to be destroyed by the central star in a planetary nebula.”

The study shows that the X-ray signal from the white dwarf has remained approximately constant in brightness between 1992, 1999, and 2002 (with observations by ROSAT, Chandra and XMM respectively). The data, however, suggests there may be a subtle, regular change in the X-ray signal every 2.9 hours, providing evidence for the remains of a planet exceptionally close to the white dwarf.

You can read the original paper here. The Helix Nebula is about 650 light years away, and is one of the most studied planetary nebula, believed to have formed when the central star collapsed into a white dwarf.

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A galaxy surrounded by clusters of hot massive stars

8:44 am

A galaxy surrounded by hot massive stars
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope of the galaxy NGC 5042, located about 48 million light years away. The picture combines data from all of Hubble’s available wavelengths from the ultraviolet to the infrared. From the caption:

Perhaps NGC 5042’s most striking feature is its collection of brilliant pink gas clouds that are studded throughout its spiral arms. These flashy clouds are called H II (pronounced “H-two”) regions, and they get their distinctive colour from hydrogen atoms that have been ionised by ultraviolet light. If you look closely at this image, you’ll see that many of these reddish clouds are associated with clumps of blue stars, often appearing to form a shell around the stars.

H II regions arise in expansive clouds of hydrogen gas, and only hot and massive stars [indicated by blue] produce enough high-energy light to create an H II region. Because the stars capable of creating H II regions only live for a few million years — just a blink of an eye in galactic terms — this image represents a fleeting snapshot of life in this galaxy.

The image also includes one star (distinguished by its four diffraction spikes) and a few background galaxies in yellow, the most obvious found in the upper and lower right.

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Lucy takes first picture of its next target asteroid

9:12 am

Lucy's future route through the solar system
Lucy’s route to the asteroids. Click for original blink animation.

The asteroid probe Lucy, on its way to the orbit of Jupiter to study numerous Trojan asteroids, has taken its first picture of the the main asteroid belt asteroid Donaldjohanson, which it will pass within 600 miles on April 20, 2025.

The map to the right shows the spacecraft’s looping route to get to the Trojans, with that image of Donaldjohanson in the lower right. Though the asteroid is about two miles side, it will remain an unresolved point of light until the day of the fly-by. This image was taken from a distance of 45 million miles. As for the asteroid’s name:

Asteroid Donaldjohanson is named for anthropologist Donald Johanson, who discovered the fossilized skeleton — called “Lucy” — of a human ancestor. NASA’s Lucy mission is named for the fossil.

After this encounter, Lucy will head to the Trojans, where it will visit its first six asteroids (including two binaries) in 2027-2028.

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New calculations now say asteroid 2024 YR4 will almost certainly not hit the Earth in 2032

9:49 am

According to an announcement from NASA yesterday, the chances of asteroid 2024 YR4 hitting the Earth in 2032 is now reduced to 0.004%, meaning that it almost certainly not a threat at that time.

There remains a 1.7% chance it will instead impact the Moon in 2032.

These refined calculations were likely achieved by looking not at the asteroid itself (it is now too far away), but at places where it might have been visible to ground-based telescopes in the past, assuming it had an orbit that will hit the Earth in 2032. Since those past observations did not see it, those orbits are thus eliminated, and the threat goes down.

Of course, the uncertainty remains. It also remains important that we obtain more detailed information about this asteroid, because it is still a potential threat to the Earth.

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Hubble takes a close look at one tiny part of the Veil Nebula

12:47 pm

A small section of the Veil Nebula
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope of just one very tiny section of the supernova remnant known as the Veil Nebula, located about 2,400 light years away.

The white dot on the inset (showing the entire Veil Nebula) marks the area covered by this closeup, focused on the one bright section of nebula in the Veil’s southwest quadrant. From the caption:

This nebula is the remnant of a star roughly 20 times as massive as the Sun that exploded about 10 000 years ago. … This view combines images taken in three different filters by Hubble’s Wide Field Camera 3 instrument, highlighting emission from hydrogen, sulphur and oxygen atoms. This image shows just a small fraction of the Veil Nebula; if you could see the entire nebula without the aid of a telescope, it would be as wide as six full Moons placed side by side.

Astronomers have been using Hubble to take periodic pictures of the Veil Nebular since 1994 in order to track changes as these gaseous gossamer strands evolve over time.

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New observations reduce odds of asteroid 2024 YR4’s 2032 Earth impact to practically zero

9:26 am

The uncertainty of science: According to a short update from NASA late yesterday, new ground-based observations have now reduced the odds that asteroid 2024 YR4’s will hit the Earth in 2032 to only 0.28 percent.

Observations made overnight on Feb. 19 – 20 of asteroid 2024 YR4 have further decreased its chance of Earth impact on Dec. 22, 2032, to 0.28%. NASA’s planetary defense teams will continue to monitor the asteroid to improve our predictions of the asteroid’s trajectory. With this new data, the chance of an impact with the Moon increased slightly to 1%.

Expect these numbers to change again in March, when the Webb telescope tracks the asteroid. And do not assume Webb will confirm these numbers. There remains great uncertainty in all these calculations, especially because there is great uncertainty about the size, mass, and make-up of 2024 YR4. It could be anywhere from 130 feet to 320 feet in diameter, and that difference makes these calculations uncertain.

In other words, it remains essential that work should begin on putting together a mission to visit and study this asteroid, now. Though it isn’t large enough to cause a worldwide extinction, it is big enough to do very significant damage, depending on where it hits.

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The uncertainty of science: Astronomers keep changing the odds of asteroid 2024 YR4 hitting the Earth in 2032

8:53 am

In the past three days three different reports from both NASA and the European Space Agency have given three different percentages for the chances that asteroid 2024 YR4 will hit the Earth in 2032.

On Tuesday, NASA calculated that the space rock had a 3.1% chance of hitting Earth in 2032, while the European Space Agency’s risk assessment sits at 2.8%.

The narrow difference is due to the two agencies’ use of different tools for determining the asteroid’s orbit and modeling its potential impact. But both percentages rise above the 2.7% chance of collision once associated with an asteroid discovered in 2004 called Apophis, making 2024 YR4 the most significant space rock to be spotted within the past two decades.

However, another update shared by NASA on Wednesday showed that 2024 YR4 has a 1.5% chance of colliding with Earth in December 2032, based on new observations now that the full moon has passed. Astronomers have anticipated that such fluctuations are possible as they gather more observational data.

While the media has generally focused mostly on the higher numbers in their knee-jerk “We’re all gonna die” approach to everything, all these different numbers simply illustrate is the generally limited nature of our data about the asteroid’s orbit and its future path. For example because such asteroids are so small, it isn’t just gravity that influences their flight path through the solar system. The Sun’s light pressure can actually have an impact, but to determine how much you need to know the exact size, shape, and rotation of the object. Right now 2024 YR4’s size is estimated to range from 130 to 320 feet in width, determining this effect is presently impossible. Nor is this the only such variable.

At the same time, the data continues to suggest that the chances of this asteroid hitting the Earth are not trivial. The sooner we can find out everything about it the better. Getting a mission to it quickly would be the best way, but so far I have heard little from NASA or anyone about such an idea.

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New data from Webb shows the Milky Way’s central supermassive black hole flares multiple times per day

9:47 am

The magnetic field lines surrounding Sagittarius A*
The magnetic field lines surrounding Sagittarius A*,
published in March 2024. Click for original image.

Though past research had shown that the Milky Way’s central supermassive black hole, dubbed Sagittarius A* (pronounced A-star) is generally quiet and inactive, new data from the Webb Space Telescope gathered over a year’s time now shows that it flares multiple times per day.

Throughout the year, the team saw how the black hole’s accretion disk emitted 5 to 6 large flares per day, of varying lengths and brightnesses, plus smaller flares in between. “[Sagittarius A*] is always bubbling with activity and never seems to reach a steady state,” Yusef-Zadeh says. “We observed the black hole multiple times throughout 2023 and 2024, and we noticed changes in every observation. We saw something different each time, which is really remarkable. Nothing ever stayed the same.”

In their paper published in The Astrophysical Journal Letters, the team outlines two possible ideas for the processes driving these flares. The faint flickers may be caused by turbulent fluctuations in the accretion disk, which could compress plasma and trigger a burst of radiation. “It’s similar to how the sun’s magnetic field gathers together, compresses and then erupts a solar flare,” Yusef-Zadeh says. “Of course, the processes are more dramatic because the environment around a black hole is much more energetic and much more extreme.”

The larger and brighter flares, on the other hand, may be caused by two fast-moving magnetic fields colliding and releasing accelerated particles. These magnetic reconnection events also have a solar parallel.

You can read their paper here [pdf]. Though this research shows unexpected activity, that activity is still relatively mild compared to other central supermassive black holes in many other galaxies. Why this difference exists remains an unanswered question.

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A rose in space

10:02 am

A rose in space
Click for original image.

Cool image time! Using the Gemini South telescope in Chile, astronomers have taken a very beautiful picture, cropped, reduced, and sharpened to post here, of a nebula dubbed LH 88 that surrounds a star cluster and is located 160,000 light years away in the Large Magellanic Cloud.

The bright stars seen in the image are widely separated, but their motions through space are similar, indicating that they have a common origin. The layered nebulous structures in LH 88 are the remnants of stars that have already died. The delicate leaves of the rose were formed by both the shockwaves from supernovae and the stellar winds of the O and B stars.

The intense radiation of these super giant O and B stars — that burn fast and explode as supernova after only a few million years of life — not only shapes the nebula, it lights the nebula’s different atoms and molecules in different colors, with red/orange representing hydrogen and blue oxygen. The white areas indicate a mixture of both.

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Astronomers demand more regulations to prevent industry from ruining the Moon’s “environment”

9:33 am

According to two articles yesterday in the British press (here and here), both quoting extensively one astronomer, if strong regulation and control (given to them of course) isn’t imposed immediately, the space tourism of billionaires is going to ruin the Moon’s pristine environment, which on its far side is especially perfect for radio astronomy. From the first link:

“There’s a rush of companies and states who might want to get in on the act on the moon,” said [astronomer Martin Elvis, who added that there were also other concerns. “There’s a desire there from the billionaire class, ‘Oh I would love to spend a week on the moon’. And you don’t need many billionaires to start adding up. If they go without coordination, then it’s a mess. We could well lose these unique opportunities to do science on a scale that we couldn’t possibly imagine.”

One of the most exciting possibilities is the use of the far side of the moon for radio astronomy. As all signals from the Earth are blocked, telescopes would, Elvis said, have the sensitivity to see into the so called “dark age” of the universe, after the big bang but before stars had formed.

Elvis is based at Harvard and also co-chairs a working group at the International Astronomical Union (IAU) that wants astronomers to be given full legal control of the Moon, preventing anyone from building anything without their permission so they can instead build their telescopes there instead.

The problem is that the astronomical community has so far shown little interest in building telescopes in space. It has instead focused on building giant Earth-based telescopes while trying to get governments to restrict the launch of satellite constellations that might interfere with those telescopes. Now it wishes to restrict lunar development as well.

Elvis however admits “It’s a sort of first come, first served situation, which encourages people to rush in and do things without thinking too hard.” Let me translate: Everyone else is beating us to the Moon because we haven’t been interested in going, so now that we might be interested we want governments to shut down our competition.

It is long past time for astronomers and the IAU to stop trying to use government to squelch everyone else and get in the game. Initiate the building of telescopes both in space and the Moon. Not only are these better places to build telescopes than on Earth, it will give astronomers some credibility when they ask others to give them their own space.

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European underwater neutrino telescope detects most powerful neutrino ever

8:53 am

A European underwater neutrino telescope that is still under construction recorded evidence in February 2023 of most powerful neutrino particle ever detected.

KM3NeT’s two neutrino detectors — one off the coast of Sicily, the other near southern France — are still under construction but already collecting data. Both contain cables hundreds of meters tall, which are strung with bundles of light sensors anchored to the seafloor.

When cosmic neutrinos interact with matter in or near a KM3NeT detector, they spawn charged particles such as muons. As those muons careen through water, they give off feeble flashes of bluish light that KM3NeT’s sensors can pick up. Clocking when different sensors spot this light can reveal a particle’s path; the brightness of the blue hue reflects the particle’s energy.

On February 13, 2023, the detector near Sicily was run through by an extremely energetic muon traveling nearly parallel to the horizon. At the time, only 21 of the planned 230 sensor cables were in place. Based on the muon’s energy and trajectory, KM3NeT scientists determined it must have been spawned by a neutrino from space rather than a particle from the atmosphere.

Simulations suggest the neutrino’s energy was around 220 petaelectron volts. The previous record holder boasted around 10 petaelectron volts.

Tracking that trajectory backwards, astronomers say the particle came from a region of space where there are a lot of active galaxies, any one of which could be the source of the neutrino. It is also possible the neutrino came instead from an interaction of high energy cosmic rays and the photons from the faint microwave background left over from the Big Bang.

As noted very correctly by one scientist, “At this point, it’s very difficult to make conclusions about the origins,” says Kohta Murase, a theoretical physicist at Penn State not involved in the research. “It’s dangerous to rely on one event.”

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Astronomers catalog large ring systems surrounding 74 stars

11:32 am

74 rings surrounding stars
Click for original image.

Using a variety of ground-based telescopes in many wavelengths, astronomers have now produced a detailed catalog of 74 stars with large dust rings similar to the Oort cloud that is believed to exist at the very outer fringes of our own solar system.

The image to the right, reduced to post here, shows all 74 stars.

The new gallery shows a remarkable diversity of structure in the belts. Some are narrow rings, while others are wider and could be categorized more as “disks” than “belts”. Moreover, some of the 74 exocomet systems have multiple rings or disks and some of those are “eccentric,” meaning not a circular orbit but more like an oval. This provides evidence that yet undetectable planets or perhaps moons are present and their gravity affects the distribution of pebbles in these systems.

You can read the paper here [pdf].

The press release implies the discovery of “exocomets” but that is not true. The belts and rings mapped are likely to have comets in them, but no such comets have been found.

The scientists say that this database can be used to better understand the formation of solar systems, though they also admit that the “limited (although much improved) size of our sample” makes any conclusions based on it very uncertain. They hope however that over time that sample size will grow.

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Astronomers find galaxy with nine rings

11:15 am

The Bullseye Galaxy
Click for original image.

Using both the Hubble Space Telescope as well as the Keck telescope in Hawaii, astronomers have discovered a galaxy with nine rings, something never seen before.

The gargantuan galaxy LEDA 1313424 is rippling with nine star-filled rings after an “arrow” — a far smaller blue dwarf galaxy — shot through its heart. Astronomers using Hubble identified eight visible rings, more than previously detected by any telescope in any galaxy, and confirmed a ninth using data from the W. M. Keck Observatory in Hawaii. Previous observations of other galaxies show a maximum of two or three rings.

More information from Keck can be found here.

Keck Observatory and Hubble’s follow-up observations helped the researchers prove which galaxy plunged through the center of the Bullseye — a blue dwarf galaxy to its center-left. This relatively tiny interloper traveled like a dart through the core of the Bullseye about 50 million years ago, leaving rings in its wake like ripples in a pond. A thin trail of gas now links the pair, though they are currently separated by 130,000 light-years.

The Hubble picture is to the right, cropped, reduced, and sharpened to post here. The small blue dwarf galaxy to the left is believed to be the galaxy that plowed through LEDA 1313424 to create the rings. LEDA is itself thought to be two and a half times the size of the Milky Way, making one of the larger known galaxies.

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200-foot-wide asteroid has a 1-in-83 chance of hitting the Earth in 2032

10:12 am

New data that has refined the solar orbit of 200-foot-wide asteroid discovered in 2024, dubbed 2024 YR4, suggests it has a 1-in-83 chance of hitting the Earth on December 22, 2032.

“Odds have slightly increased to 1 in 83,” Catalina Sky Survey engineer and asteroid hunter David Rankin wrote on BlueSky. “This is one of the highest probabilities of an impact from a significantly sized rock ever.”

Amateur astronomer Tony Dunn shared a simulation of the asteroid approach on his X feed. “Recently-discovered #asteroid 2024 YR4 may make a very close approach to Earth in 8 years. It is thought to be 40-100 meters wide. Uncertainty is still high and more and more observations are needed confirm this.”

The asteroid is rated three on the Torino risk scale, which indicates a close encounter that warrants close attention from astronomers and an over 1% chance of impact.

Though most reports say the asteroid is about 200 feet across, there is great uncertainty in that number. It could also be as large as 320 feet, or as small as 130 feet.

At the moment the risk of impact is still small. If it does occur, there is a chance it could either cause a major airburst similar to the Chelyabinsk meteor impact in 2013 that injured more than 400 people, or even impact the ground or ocean. If it hits the ocean there is a considerable risk of tsunamis. At the moment it appears its path will cross from South America to Africa in the southern hemisphere, but this data remains very uncertain at this time.

Though there will be doom-sayers, overall this is not a world destroyer. It carries some risk, but we have eight years to refine our knowledge significantly, especially when it will make a close approach of five million miles in 2028. At that time scientists should be able to better measure its size as well as its future orbit, determining more precisely whether it will even hit the Earth in 2032.

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Fast radio burst unexpectedly traced to dead and old elliptical galaxy

10:12 am

Location of Fast Radio Burst
Figure 4 from this paper [pdf].

The uncertainty of science: Using several radio telescopes working in tandem, astronomers have been able to identify the source galaxy of a fast radio burst (FRB) that repeatedly erupted throughout 2024, and discovered it came from a dead and old elliptical galaxy, not a younger galaxy as predicted.

[W]hile most FRBs originate well within their galaxies, the team traced FRB 20240209A to the outskirts of its home — 130,000 lightyears from the galaxy’s center where few other stars exist. “Among the FRB population, this FRB is located the furthest from the center of its host galaxy,” said Vishwangi Shah, a graduate student at McGill, who led the effort to pinpoint the FRB’s origins. “This is both surprising and exciting, as FRBs are expected to originate inside galaxies, often in star-forming regions. The location of this FRB so far outside its host galaxy raises questions as to how such energetic events can occur in regions where no new stars are forming.”

The small ellipse to the upper left of the giant elliptical galaxy (in yellow) marks the location of the FRB relative to its galaxy. Why it is so far outside remains a puzzle. The scientists consider two options: First, that the magnetar was once inside the galaxy but was kicked out at some point, and second, it simply could be inside a globular cluster that is too small to detect at this distance, two billion light years away.

Both explanations have problems and really don’t work.

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Hubble’s biggest image yet, of Andromeda

12:14 pm

Andromedia as seen by Hubble
Click for original image.

The image above, cropped and reduced to post here, was taken by the Hubble Space Telescope and shows the Andromeda galaxy, the Milky Way’s nearest spiral galaxy neighbor. The picture however is not one photo, but hundreds taken over the past decade.

This is largest photomosaic ever assembled from Hubble Space Telescope observations. It is a panoramic view of the neighboring Andromeda galaxy, located 2.5 million light-years away. It took over 10 years to make this vast and colorful portrait of the galaxy, requiring over 600 Hubble overlapping snapshots that were challenging to stitch together. The galaxy is so close to us, that in angular size it is six times the apparent diameter of the full Moon, and can be seen with the unaided eye.

Andromeda is not just visible to the naked eye, it is one of the largest objects seen in the sky. If you ever can get to a really dark sky location when it is above and have someone point it out to you (it remains faint), you will be astonished to find that it stretches across the sky the length of about six to eight full moons.

Thus, Hubble literally can’t take a picture of it. Its field of view is much too small. It must take many pictures to assemble a mosaic.

The picture above also hides the data contained in all those images. At the full resolution of each individual picture, Hubble has literally mapped the entire galaxy. Combined with other spectroscopic survey data taken by Hubble, astronomers over time will be able to decipher the galaxy’s makeup to better understand its formation history.

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Hubble captures a nice example of intergalactic microlensing

9:56 am

Micro-lensing at is most distinct
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken by the Hubble Space Telescope and released this week. I have specifically cropped it to focus on this ringlike feature, as it one of the nicest examples of micro-lensing I have seen. From the caption:

This curious configuration is the result of gravitational lensing, in which the light from a distant object is warped and magnified by the gravity of a massive foreground object, like a galaxy or a cluster of galaxies. Einstein predicted the curving of spacetime by matter in his general theory of relativity, and galaxies seemingly stretched into rings like the one in this image are called Einstein rings.

The lensed galaxy, whose image we see as the ring, lies incredibly far away from Earth: we are seeing it as it was when the Universe was just 2.5 billion years old. The galaxy acting as the gravitational lens itself is likely much closer. A nearly perfect alignment of the two galaxies is necessary to give us this rare kind of glimpse into galactic life in the early days of the Universe.

I am generally a very big skeptic of most astronomical studies that rely on micro-lensing. I don’t deny it happens and has been detected, as in this case. The uncertainties — such as the unknown distance to intervening galaxy that is causing the lensing — always require too many assumptions that make any reliable conclusions difficult.

Nonetheless, this object illustrates the phenomenon perfectly. The light from the distant galaxy is bent around the intervening nearer galaxy so that we that distant galaxy as a ring.

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A fading supernova 650 million light years away

10:18 am

A fading supernova 650 million light years away
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope in March 2024, and shows the fading blue light of a supernova that was first discovered by another survey telescope six weeks earlier. The galaxy, dubbed LEDA 22057, is estimated to be about 650 million light years away.

The supernova is the bright spot in the galaxy’s southeast quadrant near the edge of the galaxy’s bright body. From today’s caption release:

SN 2024PI is classified as a Type Ia supernova. This type of supernova requires a remarkable object called a white dwarf, the crystallised core of a star with a mass less than about eight times the mass of the Sun. When a star of this size uses up the supply of hydrogen in its core, it balloons into a red giant, becoming cool, puffy and luminous. Over time, pulsations and stellar winds cause the star to shed its outer layers, leaving behind a white dwarf and a colourful planetary nebula. White dwarfs can have surface temperatures higher than 100,000 degrees and are extremely dense, packing roughly the mass of the Sun into a sphere the size of Earth.

While nearly all of the stars in the Milky Way will one day evolve into white dwarfs — this is the fate that awaits the Sun some five billion years in the future — not all of them will explode as Type Ia supernovae. For that to happen, the white dwarf must be a member of a binary star system. When a white dwarf syphons material from a stellar partner, the white dwarf can become too massive to support itself. The resulting burst of runaway nuclear fusion destroys the white dwarf in a supernova explosion that can be seen many galaxies away.

The rate in which this supernova fades will help astronomers untangle the processes that cause these gigantic explosions. Though the caption makes it sound as if we know how this happens, we really don’t. There are a lot of assumptions and guesses involved in the description above, based on the limited knowledge astronomers have gathered over the past few centuries looking at many supernovae many millions of light years away.

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Astronomers discover 1st binary star system orbiting Milky Way’s central supermassive black hole

9:40 am

The stars orbiting Sag A*
The stars orbiting Sag A*. Click for original image.

Using infrared spectroscopic data gathered from 2005 to 2019 by the Very Large Telescope in Chile, astronomers have identified the first known binary star system to orbit Sagittarius A* (pronounced “A-star”), the Milky Way’s central supermassive black hole.

You can read their science paper here [pdf]. The white dot at the center of the map to the right marks the location of Sagittarius A*, while the red dot marks the present location of the binary star, dubbed D9. The other objects are the stars previously identified orbiting the central black hole, all of which are now believed to be single stars. The binary D9 has an estimated orbit around Sagittarius A* of 432 years and is thought to be less than three million years old. The two stars have approximate masses of 3.86 and 2.8 solar masses, with the smaller orbiting the larger every 372 days.

There is a lot of uncertainty in these numbers, but the data identifying the binary is quite firm. This discovery, as well as the many other stars now known to orbit Sagittarius A*, show that star formation so close to a supermassive black hole is not only possible, it is common, something astronomers a decade ago thought impossible.

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A galactic eye in heaven

12:30 pm

A galactic eye in space
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Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope as part of a project to study the star formation processes over time in this galaxy, located about 76 million light years away.

A prominent bar of stars stretches across the centre of this galaxy, and spiral arms emerge from each end of the bar. Because NGC 2566 appears tilted from our perspective, its disc takes on an almond shape, giving the galaxy the appearance of a cosmic eye.

As NGC 2566 gazes at us, astronomers gaze right back, using Hubble to survey the galaxy’s star clusters and star-forming regions. The Hubble data are especially valuable for studying stars that are just a few million years old; these stars are bright at the ultraviolet and visible wavelengths to which Hubble is sensitive. Using these data, researchers will measure the ages of NGC 2566’s stars, helping to piece together the timeline of the galaxy’s star formation and the exchange of gas between star-forming clouds and stars themselves.

To get the full picture, astronomers have also obtained infrared data from the Webb Space Telescope and millimeter/submillimeter radio wavelength data from the ALMA telescope.

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Reanalysis of Webb data discovers more than a hundred very small main-belt asteroids

11:42 am

Portrait of all 138 new asteroids
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Using data from the Webb Space Telescope in an unexpected way, astronomers have discovered 138 asteroids in the main asteroid belt, most of which are the smallest so far detected.

The picture to the right shows all 138 asteroids. The researchers had originally used Webb to study the atmospheres of the exoplanets that orbit the star TRAPPIST-1. They then thought, why not see if their data also showed the existence of asteroids in our own solar system. By blinking between multiple images they might spot the movement of solar system objects moving across the field of view. From the press release:

The team applied this approach to more than 10 000 [Webb] images of the TRAPPIST-1 field, which were originally obtained to search for signs of atmospheres around the system’s inner planets. By chance TRAPPIST-1 is located right on the ecliptic, the plane of the solar system where all planets and most asteroids lie and orbit around the Sun. After processing the images, the researchers were able to spot eight known asteroids in the main belt. They then looked further and discovered 138 new asteroids, all within tens of meters in diameter — the smallest main belt asteroids detected to date. They suspect a few asteroids are on their way to becoming near-Earth objects, while one is likely a Trojan — an asteroid that trails Jupiter.

The data is insufficient for most of these objects to chart their orbits precisely. Based on this one single study, however, it suggests that pointing Webb along the ecliptic in almost any direction will detect more such objects. Do this enough and astronomers might actually be able to get a rough census of the asteroid belt’s population.

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NSF punts on its two big telescope projects

10:50 am

Because it presently does not have sufficient funds to build both the Giant Magellan Telescope (GMT) in Chile and the Thirty Meter Telescope (TMT) in Hawaii, the National Science Foundation (NSF) asked an independent panel to look at both projects and give recommendations on which project it should go with.

That report [pdf] has now been released, and its conclusions essentially take the advice of former Yankee catcher Yogi Berra, “When you come to a fork in the road, take it.” From the report’s executive summary:

Both GMT and TMT have strong leadership, partnership and financial commitments but require $1.6 billion in NSF funding to proceed. Without this support, significant delays or project cancellations may result. The panel emphasized the critical need for congressional support, noting that without additional appropriations, NSF may face challenges balancing these projects with other national priorities, risking U.S. competitiveness in fundamental research. [emphasis mine]

If you dig into the report however you find that TMT is a far more uncertain project. GMT is already being built, while TMT is stalled because it has been unable to get political approval to build in Hawaii on Mauna Kea, even though it initially wanted to start construction almost a decade ago.

Clearly, this report was created simply as a lobbying ploy by the NSF to Congress. NSF didn’t want the report to make a choice. It wanted it to endorse both telescopes so that — rather than bite the bullet and fund one telescope with the money it has already been given by Congress — NSF could use the report to demand more funding so that it can fund both.

Though Congress is now controlled by more fiscally-minded Republicans, don’t expect them to be anymore responsible on this issue than Democrats. These guys really don’t understand basic economics, and think they have a blank check for anything they wish to do. I anticipate Congress will give NSF the extra cash for both telescopes.

The problems for TMT remain, however, and even with that cash it remains very doubtful the telescope will be built. But gee, that won’t be a problem for NSF. Who wouldn’t like getting an extra billion or two to spend as one wishes?

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Hubble takes a different look at quasar 3C 273

10:25 am

Hubble's different views of 3C 273
Click for original image.

One of the most studied objects in the sky is the quasar 3C 273, located about 2.5 billion light years away and the first quasar ever to be identified, in 1963. What makes it especially interesting is the 300,000-light-year-long jet that shoots out from it.

Astronomers have now used the Hubble Space Telescope to take a different view of 3C 273, using the telescope’s coronograph to block the central bright light so that the surrounding dimmer features can be seen. The two images to the right, reduced and sharpened to post here, show what this new image (bottom) reveals when compared to an earlier Hubble image (top).

The new Hubble views of the environment around the quasar show a lot of “weird things,” according to Bin Ren of the Côte d’Azur Observatory and Université Côte d’Azur in Nice, France. “We’ve got a few blobs of different sizes, and a mysterious L-shaped filamentary structure. This is all within 16,000 light-years of the black hole.”

Some of the objects could be small satellite galaxies falling into the black hole, and so they could offer the materials that will accrete onto the central supermassive black hole, powering the bright lighthouse.

What makes this observation even more outstanding is that the image was produced by using Hubble’s Space Telescope Imaging Spectrograph (STIS) as the coronograph to block the bright center of 3C 273. This improvisation of STIS has been done many times before, but it remains a great example of clever thinking by the astronomers who use Hubble.

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