Tag: astronomy

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
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 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
Click for original image.

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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The uncertainty of science: Star refuses to erupt when predicted

9:48 am

Based on records of two past eruptions approximately eighty years apart, astronomers had predicted that the binary star system T Coronae Borealis would erupt sometime in September 2024, brightening from magnitude 10 to as much as magnitude 2, making it one of the sky’s brighter stars for a short while.

That eruption however has so far not taken place.

“We know it has to happen,” astrophysicist Elizabeth Hays, who is watching T CrB every day using NASA’s Fermi gamma-ray space telescope, told Space.com in a recent interview. “We just can’t pin it down to the month.”

The unpredictability stems partly from limited historical records of T CrB’s outbursts. Only two such eruptions have been definitively observed in recent history: on May 12, 1866, when a star’s outburst briefly outshined all the stars in its constellation, reaching magnitude 2.0, and again on February 9, 1946, when it peaked at magnitude 3.0. These events appear to follow the star’s roughly 80-year cycle, suggesting that the next outburst may not occur until 2026. [emphasis mine]

The eruptions are thought to occur because the system’s denser white dwarf star pulls material from the lighter orbiting red giant. Over time that material accumulates on the surface of the white dwarf until it reaches critical mass, triggering a nuclear explosion that we see as the star’s brightening.

Astronomers have assumed this process is predictable, but in truth it really is not. For example, the star has brightened at other times, in 1938 and again in 2015, though not as much. These other brightenings suggest a great deal of uncertainty in the rate in which material accumulates, as well as how much is needed to trigger a nuclear burst.

Because of the possibility however of a burst at any time, astronomers have been poised eagerly now for months, observing the star regularly with the many orbiting telescopes that can observe it not only in optical wavelengths but in gamma, X-rays, and infrared. The latter capabilities didn’t exist in previous eruptions, and are now able to tell them things about the system that was impossible for earlier astronomers.

Assuming the eruption occurs at all. Despite the certainty of the astronomer’s quote highlighted above, there is no certainty here. This star system will do whatever it wants, despite the predictions of mere human beings.

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New stars shaped by old stars

8:50 am

New stars shaped by old stars
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 focused on looking at star formation in nearby galaxies. From the caption:

Evidence of star formation is scattered all around NGC 1637, if you know where to look. The galaxy’s spiral arms are dotted with what appear to be pink clouds, many of which are accompanied by bright blue stars. The pinkish colour comes from hydrogen atoms that have been excited by ultraviolet light from young, massive stars. This contrasts with the warm yellow glow of the galaxy’s centre, which is home to a densely packed collection of older, redder stars.

The stars that set their birthplaces aglow are comparatively short-lived, and many of these stars will explode as supernovae just a few million years after they’re born. In 1999, NGC 1637 played host to a supernova, pithily named SN 1999EM, that was lauded as the brightest supernova seen that year. When a massive star expires as a supernova, the explosion outshines its entire home galaxy for a short time. While a supernova marks the end of a star’s life, it can also jump start the formation of new stars by compressing nearby clouds of gas, beginning the stellar lifecycle anew.

This galaxy is one worth keeping an eye on for supernovae, since every one of those blue stars has the potential of erupting.

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Hubble vs Webb, or why the universe’s secrets can only be uncovered by looking at things in many wavelengths

11:15 am

Hubble view of Sombrero galaxy
Click for original image.

Time for two cool images of the same galaxy! The picture above shows the Sombrero Galaxy as taken by the Hubble Space Telescope in 2003. The picture below is that same galaxy as seen by the Webb Space Telescope in the mid-infrared using false colors. From the press release:

In Webb’s mid-infrared view of the Sombrero galaxy, also known as Messier 104 (M104), the signature, glowing core seen in visible-light images does not shine, and instead a smooth inner disk is revealed. The sharp resolution of Webb’s MIRI (Mid-Infrared Instrument) also brings into focus details of the galaxy’s outer ring, providing insights into how the dust, an essential building block for astronomical objects in the universe, is distributed. The galaxy’s outer ring, which appeared smooth like a blanket in imaging from NASA’s retired Spitzer Space Telescope, shows intricate clumps in the infrared for the first time.

Researchers say the clumpy nature of the dust, where MIRI detects carbon-containing molecules called polycyclic aromatic hydrocarbons, can indicate the presence of young star-forming regions. However, unlike some galaxies studied with Webb … the Sombrero galaxy is not a particular hotbed of star formation. The rings of the Sombrero galaxy produce less than one solar mass of stars per year, in comparison to the Milky Way’s roughly two solar masses a year. Even the supermassive black hole, also known as an active galactic nucleus, at the center of the Sombrero galaxy is rather docile, even at a hefty 9-billion-solar masses. It’s classified as a low luminosity active galactic nucleus, slowly snacking on infalling material from the galaxy, while sending off a bright, relatively small, jet.

In infrared the galaxy’s middle bulge of stars practically vanishes, exposing the weak star-forming regions along galaxy’s disk.

Both images illustrate the challenge the universe presents us in understanding it. Basic facts are often and in fact almost always not evident to the naked eye. We always need to look deeper, in ways that at first do not seem obvious. This is why it is always dangerous to theorize with certainty any explanation too soon, as later data will always change that explanation. You can come up with an hypothesis, but you should always add the caveat that you really don’t know.

By the way, this concept applies not just to science. Having absolute certainty in anything will almost always cause you to look like a fool later. Better to always question yourself, because that will make it easier for you to find a better answer, sooner.

We need only look at the idiotic “mainstream press” during the months leading up to the November election to have an example of someone with certainty who is now exposed as an obvious fool.

The Sombrero Galaxy as seen by Webb
Click for original image.

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A new geologic map of one of the Moon’s largest impact basins

10:00 am

Orientale Basin on the Moon
Click for original image.

Using data from Lunar Reconnaissance Orbiter (LRO), scientists have now produced a high resolution geological map of Orientale Basin, one of the largest impact basins on the Moon — at about 600 miles across — and located just on the edge of the Moon’s visible near side.

That map is to the right, reduced and sharpened to post here. You can read the paper here [pdf]. From the press release:

Planetary Science Institute Research Scientist Kirby Runyon is a lead author on a paper published in the Planetary Science Journal containing a new high-resolution geologic map of Orientale basin that attempts to identify original basin impact melt. The hope is that future researchers use this map to target sample return missions and pin down impact dates for this and other impact basins.

“We chose to map Oriental basin because it’s simultaneously old and young,” Runyon said. “We think it’s about 3.8 billion years old, which is young enough to still have its impact melt freshly exposed at the surface, yet old enough to have accumulated large impact craters on top of it as well, complicating the picture. We chose to map Orientale to test melt-identification strategies for older, more degraded impact basins whose ages we’d like to know.”

The map’s prime purpose is to pin down locations where material from the actual impact exist and can be returned to Earth for precise dating, thus helping to create a more accurate timeline of the Moon’s formation as well as the entire solar system’s accretion rate.

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A spiral galaxy as seen from the side

9:36 am

A spiral galaxy seen from the side
Click for original image.

Cool image time! The picture to the right, reduced to post here, was taken by the Hubble Space Telescope of what is believed to be a spiral galaxy seen edge-on. The galaxy itself is estimated to be 150 million light years away, and this view highlights two major features, the dust lanes that run along the galaxy’s length and its distinct central nucleus, bulging out from the galaxy’s flat plain.

The way this image was produced however is intriguing on its own:

Like most of the full-colour Hubble images released by ESA/Hubble, this image is a composite, made up of several individual snapshots taken by Hubble at different times and capturing different wavelengths of light. … A notable aspect of this image is that the two sets of Hubble data used were collected 23 years apart, in 2000 and 2023! Hubble’s longevity doesn’t just afford us the ability to produce new and better images of old targets; it also provides a long-term archive of data which only becomes more and more useful to astronomers.

All told, four Hubble data sets were used to produce the picture.

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Astronomers call for the FCC to halt all launches of satellite constellations

9:50 am

In a letter [pdf] sent to the FCC on October 24, more than one hundred astronomers demanded a complete halt of all launches of low-Earth satellite constellations until a complete environmental review can be done.

The environmental harms of launching and burning up so many satellites aren’t clear. That’s because the federal government hasn’t conducted an environmental review to understand the impacts. What we do know is that more satellites and more launches lead to more damaging gasses and metals in our atmosphere. We shouldn’t rush forward with launching satellites at this scale without making sure the benefits justify the potential consequences of these new mega-constellations being launched, and then re-entering our atmosphere to burn up and or create debris This is a new frontier, and we should save ourselves a lot of trouble by making sure we move forward in a way that doesn’t cause major problems for our future.

Under this premise, Americans would forever be forbidden from doing anything without first having detailed environmental reviews by federal government agencies. Ponder that thought for a bit.

The astronomers’ argument of course is intellectually dishonest and disingenuous, on multiple levels. It is more than evident that these launches and satellites will cause little serious harm to the atmosphere or the environment. What the astronomers really want is to block these constellations so that their ground-based telescopes will be able to continue to see the heavens unhindered.

To hell with everyone else! We need to gaze at the stars and we are more important!

What these Chicken Littles should really do is give up on ground-based astronomy entirely, and start building space-based telescopes of all kinds, and fast. They would not only bypass the satellite constellations, they would get far better data as they would also bypass the atmosphere to get sharp images of everything they look at.

Whether the FCC listens to this absurd demand depends entirely on who wins the election. A Harris administration might easily go along, shutting down not only SpaceX’s Starlink constellation (thus getting political revenge on Elon Musk for daring to campaign against Democrats) but Amazon’s Kuiper constellation as well. Such an action would likely exceed the FCC’s statutory authority, but that won’t matter to these power-hungry thugs.

Trump in turn would almost certainly shut down much of the administrative state’s mission creep into areas of regulation it has no legal business.

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WISE/NEOWISE burns up in the atmosphere

9:22 am

NASA’s Wide-field Infrared Survey Explorer (WISE, later renamed NEOWISE) has ended its fifteen years in orbit, burning up in the atmosphere on November 1, 2024.

In its initial mission it did an infrared survey of the sky, discovering millions of black holes, many of the most luminous galaxies, and numerous brown dwarfs. It was then repurposed to survey the sky for near Earth objects, asteroids that have the potential to impact the Earth, discovering more than two hundred new asteroids while tracking more precisely another 3,000. It did this by repeating its survey over and over so that moving objects could be spotted.

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A 2017 supernova as spotted by Hubble

11:20 am

Before and after of galaxy with supernova
Click for original image.

Cool image time! The pictures to the right were both compiled from photos taken by the Hubble Space Telescope, with the bottom annotated to indicate the location of a 2017 supernova that was not visible in the earlier 2005 picture.

In this collage two images of the spiral galaxy NGC 1672 are compared: one showing supernova SN 2017GAX as a small green dot, and the other without. The difference between the images is that both have been created by processing multiple individual Hubble images, each taken to capture a specific wavelength of visible light, and combining them to make a full-colour image. In one of those filtered frames, taken in 2017, the fading supernova is still visible

NGC 1672 is considered a barred spiral galaxy. Located an estimated 52 million light years away, the 2017 supernovae was not the last detected within it. In 2022 a second supernovae occurred. That’s two supernovae within five years. Meanwhile the Milky Way has not seen a supernova in more than four centuries.

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Scientists use Hubble and Webb to confirm there are as yet no planets forming in Vega’s accretion disk

11:16 am

Hubble and Webb images of Vega's accretion disk
Click for original image.

Using both the Hubble and Webb space telescopes, scientists have now confirmed, to their surprise, that the accretioni disk that surrounds the nearby star Vega is very smooth with almost no gaps, and thus apparently has not new exoplanets forming within it.

The two pictures to the right, cropped and reduced to post here, come from two different papers. The Hubble paper is here [pdf] while the Webb paper is here [pdf]. From the press release:

Webb sees the infrared glow from a disk of particles the size of sand swirling around the sizzling blue-white star that is 40 times brighter than our Sun. Hubble captures an outer halo of this disk, with particles no bigger than the consistency of smoke that are reflecting starlight.

The distribution of dust in the Vega debris disk is layered because the pressure of starlight pushes out the smaller grains faster than larger grains. “Different types of physics will locate different-sized particles at different locations,” said Schuyler Wolff of the University of Arizona team, lead author of the paper presenting the Hubble findings. “The fact that we’re seeing dust particle sizes sorted out can help us understand the underlying dynamics in circumstellar disks.”

The Vega disk does have a subtle gap, around 60 AU (astronomical units) from the star (twice the distance of Neptune from the Sun), but otherwise is very smooth all the way in until it is lost in the glare of the star. This shows that there are no planets down at least to Neptune-mass circulating in large orbits, as in our solar system, say the researchers.

At the moment astronomers consider the very smooth accretion disk surrounding Vega to be rare and exception to the rule, with most debris disks having gaps that suggest the presence of newly formed exoplanets within them. That Vega breaks the rule however suggests the rule might not be right in the first place.

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Post-collision images of two galaxies

10:56 am

Post-collision imagery by Hubble and Webb
Click for original image.

Using both the Hubble and Webb space telescopes, astronomers have now produced multi-wavelength images of the galaxies NGC 2207and IC 2163, as shown to the right.

Millions of years ago the smaller galaxy, IC 2163, grazed against the larger, NGC 2207, resulting today in increased star formation in both galaxies, indicated by blue in the Hubble photo. From the caption of the combined images:

Combined, they are estimated to form the equivalent of two dozen new stars that are the size of the Sun annually. Our Milky Way galaxy forms the equivalent of two or three new Sun-like stars per year. Both galaxies have hosted seven known supernovae, each of which may have cleared space in their arms, rearranging gas and dust that later cooled, and allowed many new stars to form.

The two images to the left leaves the Hubble and Webb separate, making it easier to see the different features the different wavelengths reveal. From this caption:

In Hubble’s image, the star-filled spiral arms glow brightly in blue, and the galaxies’ cores in orange. Both galaxies are covered in dark brown dust lanes, which obscure the view of IC 2163’s core at left. In Webb’s image, cold dust takes centre stage, casting the galaxies’ arms in white. Areas where stars are still deeply embedded in the dust appear pink. Other pink dots may be objects that lie well behind these galaxies, including active supermassive black holes known as quasars.

The largest and brightest pink area in the Webb image, on the bottom right and a blue patch in the Hubble image, is where a strong cluster of star formation is presently occurring.

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Arecibo telescope collapsed because of a surprising engineering failure that inspections still should have spotted

1:41 pm

Illustration of cable failure at Arecibo

According to a new very detailed engineering analysis into the causes of the collapse of the Arecibo radio telescope in Puerto Rico in 2020, the failure was caused first by a surprising interaction between the radio electronics of Arecibo and the traditional methods used to anchor the cables, and second by a failure of inspections to spot the problem as it became obvious.

The surprising engineering discovery is illustrated to the right, taken from figure 2-6 of the report. The main antenna of Arecibo was suspended above the bowl below by three main cables. The figure shows the basic design of the system used to anchor the cable ends to their sockets. The end of the cable bunches would be inserted into the socket, spread apart, and then zinc would be poured in to fill the gap and then act as a plug and glue to hold the cables in place. According to the report, this system has been used for decades in many applications very successfully.

What the report found however was at Arecibo over time the cable bunch and zinc plug slowly began to pull out of the socket, what the report labels as “zinc creep.” This was noted by inspectors, but dismissed as a concern because they still believed the engineering margins were still high enough to prevent failure at this point. In fact, this is exactly where the structure failed in 2020, with the first cable separating as shown in August 2020. The second cable did so in a similar manner in November 2020.

The report concluded that the “only hypothesis the committee could develop that provides a plausible but unprovable answer to all these questions and the observed socket failure pattern is that the socket zinc creep was unexpectedly accelerated in the Arecibo Telescope’s uniquely powerful electromagnetic radiation environment. The Arecibo Telescope cables were suspended across the beam of ‘the most powerful radio transmitter on Earth.'”

The report however also notes that the regular engineering inspections of the telescope had spotted this creep, which was clearly unusual and steadily becoming significant, and did not take action to address the issue when it should have. It also noted the slow response of the bureaucracy, not only to the damage caused earlier to the facility by Hurriane Maria in 2017, but to obtaining the funding for any repairs.

Ray Lugo [the principal investigator for Arecibo] described to the committee how months of his time during 2018 were spent writing, resubmitting, and justifying repair funding proposals. Repairs had to go through the traditional “bid and proposal” process, described in more detail below, which added years of delay.

We can forgive the inspectors somewhat for not noting the creep when they should, as its cause appears to be very unusual, still uncertain and rare, but the red tape that prevented proper and quick repair effort after the hurricane is shameful. Had the telescope gotten the proper support on time, the creep itself might have even been addressed, because the resources would have been there to deal with it.

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Using spectroscopic data, astronomers create 3D map of ancient supernova remnant

10:55 am

Supernova 1181
Click for original image.

Astronomers have now createdsdft a 3D map of the remnant formed by a supernova that occurred in 1181, using detailed spectroscopic data to determing which remnant filaments are moving towards us and which are moving away.

The picture to the right is from figure 1 of their paper, and shows how the filaments radiate out from the center in straight lines, something that is unusual for such remnants. It was taken in 2023 by a ground-based telescope at Kitt Peak in Hawaii. From simple optical data it is impossible however to determine which filaments are in the rear, expanding away from us, and which are in the front, expanding towards us.

To probe the three-dimensional structure of the supernova remnant, the astronomers turned to KCWI, an instrument that can capture multiwavelength, or spectral, information for every pixel in an image. This is like breaking apart the light captured in every pixel into a rainbow of colors. The spectral information enabled the team to measure the motions of the filaments poking out from the center of the explosion and ultimately create a 3D map of the structure. The filament material that is flying toward us shifted toward the blue higher-energy portion end of the visible spectrum (blue-shifted), while light from material moving away from us shifted toward the red end of the spectrum (red-shifted).

…The results showed that the filament material in the supernova is flying outward from the site of the explosion at approximately 1,000 kilometers per second. “We find the material in the filaments is expanding ballistically,” says Cunningham. “This means that the material has not been slowed down nor sped up since the explosion. From the measured velocities, looking back in time, you can pinpoint the explosion to almost exactly the year 1181.”

The 3D information also revealed a large cavity inside the spindly, spherical structure in addition to some evidence that the supernova explosion of 1181 occurred asymmetrically.

Using this data, they were able to create that 3D map, shown below in a coarse animation video.
» Read more

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The uncertainty of science: New research suggests first image in ’22 of Milky Way’s central black hole is likely not accurate

10:25 am

Sagittarius A*
The original interpretation. Click for full image.

The new interpretaion
The new asymmetrical interpretation. Click for original image.

Surprise, surprise! A new analysis of the data behind the 2022 false-color radio image of the supermassive black hole at the center of the Milky Way, posted to the right, suggests that image was not accurately interpreted from the data.

Astronomers led by the National Astronomical Observatory of Japan (NAOJ) say their analysis points at Sagittarius A* having an elongated accretion disk, as opposed to the ring-like “doughnut” image released in 2022 by an international team called the Event Horizon Telescope (EHT) collaboration.

The EHT image shows a central dark region where the hole resides, circled by the light coming from super-heated gas accelerated by immense gravitational forces.

But a new paper published today in Monthly Notices of the Royal Astronomical Society suggests that part of this appearance may actually be an artefact because of the way the image was put together. … Assistant professor Miyoshi Makoto, of the NAOJ, said: “Our image is slightly elongated in the east-west direction, and the eastern half is brighter than the western half. We think this appearance means the accretion disk surrounding the black hole is rotating at about 60 per cent of the speed of light.” He added: “Why, then, did the ring-like image emerge? Well, no telescope can capture an astronomical image perfectly. We hypothesise that the ring image resulted from errors during EHT’s imaging analysis and that part of it was an artefact, rather than the actual astronomical structure.”

It must be noted that this false color radio image was assembled from eight different radio telescopes across the globe, and to bring the data together required a great deal of massaging. While most astronomers appear to favor the top picture, it is just as likely that the bottom picture is a better representation. Either way, both must be considered in any future studies of Sagittarius A*’s environment and structure.

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SpaceX asks FCC for license revision for launching nearly 30,000 Starlink satellites

8:51 am

SpaceX on October 11, 2024 submitted a request to the FCC to revise its Starlink satellite license to cover a revised plan for its second generation satellites that includes a request to place 29,988 Starlink satellites in orbit.

SpaceX first requests several amendments to the orbital parameters of its Gen2 system between 340 km and 365km altitude to keep pace with rapidly evolving global demand for high-quality broadband. First,SpaceX amends the inclination of its orbital shell at a nominal altitude of 345 km from 46 degrees to 48 degrees. SpaceX also amends its pending Gen2 application to seek authority to operate satellites in its Gen2 system in two additional orbital shells — at 355 km altitude in a 43-degree inclination and at 365 km altitude in a 28- or 32-degree inclination. The total number of operational satellites will remain 29,988 satellites across the amended Gen2 system.

With the exception of its polar shell at 360 km, which will remain unchanged, SpaceX also amends its application to more flexibly distribute satellites in its shells between 340 km and 365 km than requested in its pending application, specifically, in up to 72 planes per shell and up to 144 satellites per plane. While this reconfiguration will result in two additional shells and a higher maximum number of orbital planes and satellites per plane for all but one shell between 340 km and 365 km, the total number of operational satellites in the Gen2 system will remain 29,988 satellites.

In the company’s previous request for this number of satellites, the FCC had approved only 7,500, the full request still pending. We can expect objections from the other big satellite constellations to this request. The FCC’s response remains unclear. There could be legitimate reasons to limit SpaceX request, but it is also possible politics will enter the decision as well, for illegitimate reasons.

Meanwhile, astronomers are already whining about the problems these Starlink satellites will cause to their ground-based telescopes. It seems these so-called brilliant scientists can’t get it through their heads that astronomy from Earth will become increasingly difficult in the coming years — with hundreds of thousands of satellites planned from many satellite constellations, not just SpaceX — while astronomy from space has always been a better choice anyway. Rather than demand regulation or restrictions on these new satellite constellations, they should be pushing hard to developing new orbiting telescopes, now, for launch as quickly as possible.

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A galaxy squashed as it plows its way through the intergalactic medium

9:21 am

A galaxy squashed by a vacuum
Click for original image.

Time for another cool image on this relatively slow day in the space news business. The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope and released today by the European Space Agency’s press department. From the caption:

Appearances can be deceiving with objects so far from Earth — IC 3225 itself [the galaxy to the right] is about 100 million light-years away — but the galaxy’s location suggests some causes for this active scene, because IC 3225 is one of over 1300 members of the Virgo galaxy cluster. The density of galaxies in the Virgo cluster creates a rich field of hot gas between them, the so-called ‘intracluster medium’, while the cluster’s extreme mass has its galaxies careening around its centre in some very fast orbits. Ramming through the thick intracluster medium, especially close to the cluster’s centre, places an enormous ‘ram pressure’ on the moving galaxies that strips gas out of them as they go.

IC 3225 is not so close to the cluster core right now, but astronomers have deduced that it has undergone this ram pressure stripping in the past. The galaxy looks as though it’s been impacted by this: it is compressed on one side and there has been noticeably more star formation on this leading edge, while the opposite end is stretched out of shape. Being in such a crowded field, a close call with another galaxy could also have tugged on IC 3225 and created this shape. The sight of this distorted galaxy is a reminder of the incredible forces at work on astronomical scales, which can move and reshape even entire galaxies!

What makes the impact on this galaxy of that intercluster medium so astonishing is that medium is so relatively empty of material. The space between galaxies in the Virgo cluster is in all intents and purposes a vacuum far more empty than any that we can create in a chamber on Earth. And yet it was enough to distort this galaxy and cause star formation on the galaxy’s leading edge.

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A water sprinkler in space

11:42 am

A sprinkler in space

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 long term program to monitor changes in the R Aquarii binary star system, located about 700 light years away.

R Aquarii belongs to a class of double stars called symbiotic stars. The primary star is an aging red giant and its companion is a compact burned-out star known as a white dwarf. The red giant primary star is classified as a Mira variable that is over 400 times larger than our Sun. The bloated monster star pulsates, changes temperature, and varies in brightness by a factor of 750 times over a roughly 390-day period. At its peak the star is blinding at nearly 5,000 times our Sun’s brightness.

When the white dwarf star swings closest to the red giant along its 44-year orbital period, it gravitationally siphons off hydrogen gas. This material accumulates on the dwarf star’s surface until it undergoes spontaneous nuclear fusion, making that surface explode like a gigantic hydrogen bomb. After the outburst, the fueling cycle begins again.

This outburst ejects geyser-like filaments shooting out from the core, forming weird loops and trails as the plasma emerges in streamers. The plasma is twisted by the force of the explosion and channeled upwards and outwards by strong magnetic fields. The outflow appears to bend back on itself into a spiral pattern. The plasma is shooting into space over 1 million miles per hour – fast enough to travel from Earth to the Moon in 15 minutes! The filaments are glowing in visible light because they are energized by blistering radiation from the stellar duo.

The press release likens these filaments to the spray thrown out by a water sprinkler, and I must say that’s an apt description.

Since 2014 scientists have taken regular pictures of R Aquarii, and found that the central structures have been changing in a perceptible manner, despite their gigantic size. Below is a movie created from five photos taken from 2014 to 2023.
» Read more

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ESA releases first section of grand mosaic of the sky to be produced by Euclid

9:29 am

Euclid's first released mosaic
For original images, go here, here, and here.

The European Space Agency (ESA) yesterday released the first mosaic section of a grand atlas of the sky that its recently launched Euclid space telescope was designed to produce.

The image to the right, assembled from several images but of very low resolution to post here, will give my readers an idea of Euclid’s capabilities. The top image shows this first mosaic in green, made up of 260 photos, laid on top of the sky atlases produced by the Gaia and Plank orbiting telescopes. As you can see, it covers only about 12% of the sky, but was also produced in only the last six months, since science observations began in February. When complete, the Euclid atlas will cover one third of the sky, and provide very high resolution data for that entire area.

The middle image provides a close-up of that mosaic, albeit in very low resolution.

This first piece of the map already contains around 100 million sources: stars in our Milky Way and galaxies beyond. Some 14 million of these galaxies could be used to study the hidden influence of dark matter and dark energy on the Universe. “This stunning image is the first piece of a map that in six years will reveal more than one third of the sky. This is just 1% of the map, and yet it is full of a variety of sources that will help scientists discover new ways to describe the Universe,” says Valeria Pettorino, Euclid Project Scientist at ESA.

The bottom image, once again at low resolution to post here, zooms into only one small section of that mosaic, and illustrates the high level of detail each Euclid image will contain. Though the details in this photo seem a bit fuzzy, at full resolution they remain remarkably sharp. To get an idea of how good that resolution is, see an earlier Euclid close-up photo released in May.

Euclid doesn’t take pictures with the quite the resolution of Hubble (its primary mirror at 1.2 meters diameter is half the width). While Hubble was designed to zoom in at specific objects and do so over and over if desired, Euclid will instead provide a high resolution snapshot of the entire sky, at a resolution almost as good, in both optical and infrared wavelengths.

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Viewing Comet Tsuchinshan-ATLAS when it enters the evening sky

9:20 am

Link here. For those living in the northern hemisphere, Comet Tsuchinshan-ATLAS will be bright and visible to the naked eye just after sunset beginning tomorrow.

“As soon as October 11th, ambitious comet spotters may pick up the comet during twilight just above the western horizon,” says Sky & Telescope Contributing Editor Bob King. “Binoculars will help you see the comet throughout its appearance.”

About 40 minutes after sunset on Friday, find a spot with a good view down to the western horizon. The first thing that will catch your eye will be the bright planet Venus, the Evening Star — that’s your starting point. Hold your fist out at arm’s length; the comet is about 2½ fists to Venus’s right. The comet will still look tiny in Friday’s twilight — like a hazy star with a small tail — and will set while twilight is still in progress.

Comet Tsuchinshan-ATLAS (pronounced choo-cheen-SHAHN) will remain visible for the next ten days, with the best viewing likely from October 13th to October 16th.

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