Tag: Hubble Space Telescope

Hubble looks at the Trifid Nebula again

9:59 am

Trifid Nebula as seen by Hubble
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 today. It shows a small section of the Trifid Nebula, located about 5,000 light years away.

This location has been imaged numerous times in the past by Hubble. The area shown illustrates some fundamental aspects of stellar and nebula formation. The dark area in the lower right is a thick dust cloud. Several energetic O and B supermassive stars are out of view at the top. The radiation from these stars (indicated by the blue), is hitting that dust cloud and literally destroying it. It appears that the foreground “horn” exists because a larger object is blocking the radiation, allowing dust to survive in the background.

I have no explanation for the background “horn”.

This new image was taken in parallel with an image of the entire Trifid Nebula, taken by the new Rubin Telescope in Chile. Though Rubin cannot see with the same resolution as Hubble, its image is quite worthwhile viewing.

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New data from Webb suggests two of Uranus’ outer rings are starkly different

11:03 am

The outer two rings of Uranus as seen by Webb in the infrared
Click for original image.

Using new infrared data obtained by the Webb Space Telescope in February 2025 and combined with optical data previously obtained by the ground-based Keck Observatory in 2007 and the Hubble Space Telescope in 2003 and 2013, astronomers now think that two adjacent outer rings of Uranus are completely different from each other, with one ring largely created by icy material thrown off the moon Mab.

The infrared image to the right was taken by Webb, and shows the two subject rings, dubbed v and μ.

Though they orbit the same planet, Uranus’s μ and ν rings are fundamentally different. Prior observations with the combined Keck Observatory and HST showed that the μ ring appeared blue, a signature of extremely small particles, while the ν ring’s reddish hue points to a more typical dusty ring. Why the rings were so different remained a mystery, though.

When JWST came on-line and observed Uranus, the research team used all its data, taken at different infrared wavelengths, in combination with Keck Observatory and HST observations to construct a complete spectrum from the visible through to infrared. By analyzing how sunlight reflects off the rings, the team identified a strong absorption feature near a wavelength of 3 microns (3 millionths of a meter) visible in the infrared for both rings. Beyond that shared feature, the differences become clear when simulating the detailed spectra: the μ ring closely matches the spectral signature of water ice, while the ν ring is clearly composed of rocky material, mixed with approximately 10–15% carbon-rich organic compounds commonly found in the outer solar system.

The μ ring seems to be made up of tiny icy grains knocked off the planet’s small (12-km sized) moon, Mab, by micrometeorite impacts. Interestingly, the icy composition of the μ ring also confirms that the moon Mab is composed mostly of water-ice.

According to the paper’s abstract, the v ring is dusty and, “like typical dusty rings, is sourced from collisions between, and micrometeoroid impacts on, larger but as yet unseen parent bodies orbiting within this ring. These bodies must be composed in part of organic materials [molecules with carbon as one component].”

This data really only raises more questions than it answers. For one, what are those larger objects within the v ring? Without a nearby orbiter there is no way to find them. For another, this new data really doesn’t explain why these two adjacent rings are so different. What processes force such a distinct distribution of materials?

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Voyager-2 discovered Neptune to be a planet of quickly changing weather

10:53 am

Neptune's fast changing weather
Click for source.

Cool image time! When Voyager-2 flew past Uranus in 1986, the data showed the gas giant’s weather to be relatively sedate and quiet, with little changing during the fly-by. Scientists expected this: Uranus’s distance from the Sun meant it got little energy to fuel an active climate, with any activity produced by internal heating due to the gravitational pressure of its mass. And Uranus did not produce that much heat internally.

When Voyager-2 passed Neptune three year later, the scientists expected something similar, or even less, due to Neptune’s greater distance from the Sun. Instead, Voyager-2’s data showed Neptune’s weather patterns to be changing constantly and quickly, as illustrated by the three images of the Great Dark Spot to the right, the biggest storm on Neptune at that time and located in the planet’s southern mid-latitudes.

The bright cirrus-like clouds of Neptune change rapidly, often forming and dissipating over periods of several to tens of hours. In this sequence spanning two rotations of Neptune (about 36 hours) Voyager 2 observed cloud evolution in the region around the Great Dark Spot at an effective resolution of about 60 miles per pixel. The surprisingly rapid changes which occur over the 18 hours separating each panel shows that in this region Neptune’s weather is perhaps as dynamic and variable as that of the Earth. However, the scale is immense by our standards — the Earth and the [Great Dark Spot] are of similar size.

In Neptune’s frigid atmosphere, where temperatures are as low as 55 degrees Kelvin (-360 F), the cirrus clouds are composed of frozen methane rather than Earth’s crystals of water ice.

Subsequent observations by the Hubble Space Telescope in 1994 found this Great Dark Spot was gone, replaced by a comparable storm in the northern hemisphere. Further Hubble observations found Neptune’s storms tend to last about two years, fading as they drifted towards the equator. Those observations however also detected storms drifting away from the equator. Other research suggested the storms might be influenced by the Sun’s sunspot cycle.

All of the data post-Voyager-2 remains very coarse and uncertain, as we are looking at Neptune at a great distance. Thus, no theory about what is happening carries much weight, especially because we do not know why Neptune produces so much more internal heat than Uranus, fueling this fast-changing weather. For example, Neptune gets 1/20th of the energy received by Jupiter, yet its atmosphere appears even more active and variable.

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A soft barred galaxy with an active nucleus

9:56 am

A barred galaxy with an active galactic nucleus
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 two different surveys aimed at studying galaxies with what scientists call active galactic nuclei.

IC 486 lies right on the edge of the constellation Gemini (the Twins), around 380 million light-years from Earth. Classified as a barred spiral galaxy, it features a bright central bar-shaped structure from which its spiral arms unfurl, wrapping around the core in a smooth, almost ring-like pattern.

…At the galaxy’s center a noticeable white glow outshines the starlight around it. This is light given off by IC 486’s active galactic nucleus (AGN), powered by a supermassive black hole more than 100 million times the mass of the Sun. Every sufficiently large galaxy hosts a supermassive black hole at its center, but some of these black holes are particularly ravenous, marshaling vast amounts of gas and dust into swirling accretion discs from which they feed. The intense heat generated by the orbiting disc of material generates intense radiation up to and including X-rays, which can outshine the entire rest of the galaxy. In these cases, the galaxy is known as an active galaxy, with an AGN at its center.

For comparison, the relatively inactive supermassive black hole at the center of the Milky Way has a mass of about four million Suns, considerably smaller than IC 486’s. Why one is active and the other not however is not yet truly understood, though their different masses might provide part of the explanation.

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Astronomers detect the first comet whose nucleus’ reversed its rotation

11:28 am

Astronomers using data collected by the orbiting Gehrels Swift and Hubble space telescopes now think the nucleus of a small comet reversed its rotation sometime in 2017, caused by the force of the material sublimated off its surface.

From the abstract of their paper [pdf]:

The rotations of cometary nuclei are known to change in response to outgassing torques. The nucleus of the Jupiter-family comet 41P/Tuttle–Giacobini–Kresak exhibited particularly dramatic rotational changes when near perihelion in 2017 April. Here, we use archival Hubble Space Telescope observations from 2017 December to study the postperihelion lightcurve of the nucleus and to assess the nucleus size.

From both Hubble photometry and nongravitational acceleration measurements, we find a diminutive nucleus with effective radius 500 ± 100 meters. Systematic optical variations are consistent with a two-peaked (i.e., rotationally symmetric) lightcurve with period 0.60 ± 0.01 days, substantially different from periods measured earlier in 2017. The spin of the nucleus likely reversed between perihelion in 2017 April and December as a result of the outgassing torque.

In plain English: the thrust of the material being thrown from the surface as the comet made its close approach to the Sun was sufficient to slow and then reverse the nucleus’s rotation. This process was helped by the relatively small size of the nucleus compared to the material being sublimated from it.

The data also suggests the nucleus was once much larger, and has been whittled down to its present small size as it made its multiple close fly-bys of the Sun during the past 1,500 years. Rather than break-up, as most comets do at some point as their nucleus gets smaller, this comet’s nucleus simply kept shrinking, to the point that the thrust of that material could change its rotation.

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Webb and Hubble take a look at Saturn

9:37 am

Saturn seen by Webb and Hubble

Astronomers using both the Hubble Space Telescope and the Webb Space Telescope have produced new complementary views of the ringed planet Saturn.

Those photographs are shown above, with Webb’s false-color infrared image to the left and Hubble’s optical image to the right. From the press release:

In the Webb image, a long-lived jet stream known as the “ribbon wave” meanders across the northern mid-latitudes, influenced by otherwise undetectable atmospheric waves. Just below that, a small spot represents a lingering remnant from the “Great Springtime Storm” of 2010 to 2012. Several other storms dotting the southern hemisphere of Saturn are visible in Webb’s image, as well. All these features are shaped by powerful winds and waves beneath the visible cloud deck, making Saturn a natural laboratory for studying fluid dynamics under extreme conditions.

…In Webb’s infrared image, the rings are extremely bright because they are made of highly reflective water ice. In both images, we’re seeing the sunlit face of the rings, a little less so in the Hubble image, hence the shadows visible underneath on the planet.

There are also subtle ring features such as spokes and structure in the B ring (the thick central region of the rings) that appear differently between the two observatories. The F ring, the outermost ring, looks thin and crisp in the Webb image, while it only slightly glows in the Hubble image.

The press release says little about the Hubble image, mostly because it shows little new by itself. It however is part of an on-going decade-long survey using Hubble to track Saturn’s changing weather patterns.

While both images are valuable, they also highlight our present limits in observing Saturn. Views from Earth can only see so much. It is like trying to watch a football game from ten miles away, with binoculars. And sadly, no mission is presently planned to return to Saturn.

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Changes to the Crab Nebula after a quarter century

9:44 am

The Crab Nebula, changes after a quarter century
For original images go here and here.

Using the Hubble Space Telescope, astronomers have obtained a new high resolution image of the Crab Nebula, and by comparing it with earlier Hubble images taken in 1999/2000 have been able to track the continuing expansion and evolution of this supernova remnant over a period now covering almost a quarter century.

The supernova itself became visible on Earth in 1054, though it actually erupted about 6,500 years earlier, as the Crab Nebula is 6,500 light years away. In the 25 years Hubble has been tracking the remnant’s expansion astronomers estimate it is expanding at about 3.4 million miles per hour.

[William Blair of Johns Hopkins University] noted that filaments around the periphery of the nebula appear to have moved more compared to those in the center, and that rather than stretching out over time, they appear to have simply moved outward. This is due to the nature of the Crab as a pulsar wind nebula powered by synchrotron radiation, which is created by the interaction between the pulsar’s magnetic field and the nebula’s material. In other well-known supernova remnants, the expansion is instead driven by shockwaves from the initial explosion, eroding surrounding shells of gas that the dying star previously cast off.

The new, higher-resolution Hubble observations are also providing additional insights into the 3D structure of the Crab Nebula, which can be difficult to determine from a 2D image, Blair said. Shadows of some of the filaments can be seen cast onto the haze of synchrotron radiation in the nebula’s interior. Counterintuitively, some of the brighter filaments in the latest Hubble images show no shadows, indicating they must be located on the far side of the nebula.

A movie showing the changes between these two images can be seen here. It is worth your while to take a look. These optical images will be further enhanced as the Webb Space Telescope gathers infrared data.

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Old and new optical space telescopes team up to view the Cat’s Eye

9:39 am

Cat's Eye Nebula as seen by both Hubble and Euclid
Click for original images.

Astronomers using both NASA’s long established Hubble Space Telescope and Europe’s new Euclid space telescope have produced new optical/infrared images of the Cat’s Eye planetary nebula.

Those images are to the right, cropped, reduced, and sharpened to post here. The Hubble image at bottom shows the complex structure of the nebula itself, located about 4,400 light years away and believed created by the inner orbital motions of a binary star system that act almost like the blades in a blender, mixing the material thrown off by one or both of the stars as they erupt in their latter stages of life.

In Euclid’s wide, near-infrared, and visible light view, the arcs and filaments of the nebula’s bright central region are situated within a halo of colorful fragments of gas zooming away from the star. This ring was ejected from the star at an earlier stage, before the main nebula at the center formed. The whole nebula stands out against a backdrop teeming with distant galaxies, demonstrating how local astrophysical beauty and the farthest reaches of the cosmos can be seen together with Euclid.

Euclid has a primary mirror 1.2 meters in diameter, about half that of Hubble. Though it can’t zoom in with the same resolution, its view is as sharp since it is in space above the atmosphere. It thus provides a wider view, which in this case helps provide a larger context to the detailed close-up view provided by Hubble.

In many ways Euclid is Hubble’s replacement, produced by the European Space Agency, as NASA and the American astronomy community has not been able to get together to build their own new optical orbiting telescope.

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Webb imaged a star before it went supernova

11:14 am

Webb detection of a supernova progenitor
Click for original image.

One of the biggest challenges facing astronomers for more than four centuries has been the detection of a star prior to its going supernova. Until very recently, no such detection had ever happened, and so astronomers could only guess at the kind of stars or binary systems that might result in these gigantic stellar explosions.

In recent years the improvement in telescopes, both in orbit and on the ground, has produced some successes, whereby the progenitor star was imaged in archival imagery and found after the explosion. The sample however has been small, and the data limited to only a few wavelengths.

Now, the Webb Space Telescope has made its first detection of a supernova progenitor, in the infrared. That image is to the right, showing the star prior to the June 2025 supernova explosion.

By carefully aligning Hubble and Webb images taken of NGC 1637, the team was able to identify the progenitor star in images taken by Webb’s MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) in 2024. They found that the star appeared surprisingly red – an indication that it was surrounded by dust that blocked shorter, bluer wavelengths of light. “It’s the reddest, most dusty red supergiant that we’ve seen explode as a supernova,” said graduate student and co-author Aswin Suresh of Northwestern University.

This excess of dust could help explain a long-standing problem in astronomy that could be described as the case of the missing red supergiants. Astronomers expect the most massive stars that explode as supernovas to also be the brightest and most luminous. So, they should be easy to identify in pre-supernova images. However, that hasn’t been the case.

One potential explanation is that the most massive aging stars are also the dustiest. If they’re surrounded by large quantities of dust, their light could be dimmed to the point of undetectability. The Webb observations of supernova 2025pht support that hypothesis.

You can read the peer-reviewed paper here [pdf].

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First visual detection of another star’s heliosphere

9:38 am

A baby star's heliosphere
Click for full image.

Using both the Hubble Space Telescope and the Chandra X-ray Observatory, astronomers have made the first visual detection of another star’s heliosphere, in both X-rays and in the infrared.

The image to the right, cropped to post here.

Astronomers have nicknamed the HD 61005 star system the “Moth” because it is surrounded by large amounts of dust patterned similarly to the shape of a moth’s wings when viewed through infrared telescopes. The wings are formed from material left behind after the formation of the star, similar to the Kuiper Belt in our own solar system. Observations of these wings with NASA’s Hubble Space Telescope showed that the interstellar matter surrounding HD 61005 is about a thousand times denser than that around the Sun.

The wings are the points to the left and right. The star’s young heliosphere, which they dub an “astrosphere,” is the purple glow above and below. From the caption:

In this composite image of HD 61005 in the inset, X-rays from Chandra (purple and white) have been combined with infrared data from Hubble (blue and white). Chandra reveals a bright source of X-rays in the center of the image, which is the star itself surrounded by the star’s astrosphere. The wing-like structure sweeping away from the star in the infrared image is dusty material that remained behind after the formation of the star. These wings have been swept backwards as they fly through space.

As this star and its solar system are very young, what we have is a very dusty accretion disk interacting with a very temperamental baby star.

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Hubble eyes the Egg Nebula

10:48 am

Hubble eyes the Egg Nebula
Click for original image.

Cool image time! The picture to the right, reduced to post here, was taken by the Hubble Space Telescope as part of a study of “preplanetary nebula,” the initial stages of a planetary nebula that forms as some star types begin dying. From the caption:

Many preplanetary nebulae are relatively dim and hard to spot. They are made of layers of gas ejected by the star, but that star is not yet hot enough to ionise the gas and cause it to glow. The Egg Nebula is relatively unique, easily visible as a sparkling jewelled egg in space. Powerful beams of starlight blast out of the inner cloud, two a-side, giving a breathtaking illumination to this cosmic structure. Fast-moving outflows of hot molecular hydrogen also emerge from within the dust cloud, visible just at the base of the searchlight beams. These outflows glow with infrared light, which is shown in this image by orange highlights.

The central cloud of dust is surrounded by concentric rings, themselves made up from thin, faint arcs of gas. These were created by successive outbursts from the central star, which ejected a little more material from its outer surface every few hundred years. The beams of starlight are reflected by these layers of gas, creating an appearance like ripples on the surface of water. The way that gas molecules reflect and scatter light gives a bluish colour to the arcs. The reflected starlight reveals important details about the central star, which is impossible to view directly in its dusty shell.

Many planetary nebula get their spectacular shapes because they have a binary star system in their center, that act like the blades in a blender as they circle each other, mixing the materials the stars’ eject to form those shapes. Because of those surrounding shells, it is often impossible to determine with the nebula has a single central star, or a binary system.

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A galaxy’s swirling dust lanes

12:07 pm

A galaxy with swirling dust lanes
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken by the Hubble Space Telescope as part of follow-up observations of a now faded supernovae that occurred there two years earlier.

This was on purpose: the aim of the observations was to witness the aftereffects of the supernova and examine its surroundings, which can only be done once the intense light of the explosion is gone.

The galaxy itself, NGC 7722, is 187 million light years away, and is unusual in itself.

A “lenticular”, meaning “lens-shaped”, galaxy is a type that sits in between the more familiar spiral galaxies and elliptical galaxies. It is also less common than these — partly because when a galaxy has an ambiguous appearance, it can be hard to determine if it is actually a spiral, actually an elliptical galaxy, or something in between. Many of the known lenticular galaxies sport features of both spiral and elliptical galaxies. In this case, NGC 7722 lacks the defined arms of a spiral galaxy, while it has an extended, glowing halo and a bright bulge in the center similar to an elliptical galaxy. Unlike elliptical galaxies, it has a visible disc — concentric rings swirl around its bright nucleus. Its most prominent feature, however, is undoubtedly the long lanes of dark red dust coiling around the outer disc and halo.

The streak in the lower left is a very distant background galaxy, seen on edge.

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Astronomers use AI to discover hundreds of weird galaxies in Hubble archive

10:23 am

Weird galaxies in the Hubble archive, found with AI
Click for original image.

In what is a perfect example of the proper use of artificial computer intelligence (AI), astronomers have now used this programming to analyze almost 100 million images taken by the Hubble Space Telescope over the decades to find any galaxies hidden there that have “anomalies” or unusual shapes.

The team analyzed nearly 100 million image cutouts from the Hubble Legacy Archive, each measuring just a few dozen pixels (7 to 8 arcseconds) on a side. They identified more than 1,300 objects with an odd appearance in just two and a half days — more than 800 of which had never been documented in scientific literature.

The six galaxies to the right are just a small sample. All six were previously unidentified, and include “three lenses with arcs distorted by gravity, one galactic merger, one ring galaxy, and one galaxy that defied classification” (the galaxy at the top left). From the European Space Agency’s (ESA) press release:

The strange, bi-polar galaxy seen here is certainly anomalous, with its compact, swirling core and two open lobes at the sides. Exactly what kind of galaxy it is is unclear, and it was not previously known to astronomers.

As noted in the first link, the volume of data that astronomers are now collecting from ground-based and orbiting telescopes — many of which are survey telescopes that photograph the entire sky repeatedly — has actually become a problem. They have great data, but don’t have the time or human resources to study it sufficiently. Even employing large numbers of ordinary citizens, working at home with their own computers, can’t get the job done.

This is the kind of grunt work that AI is ideally made for. It can quickly review the data and identify objects that don’t fit normal expectations. Humans then can do the real work, finding the most interesting of these strange objects, such as the top left galaxy, and devote human creativity to studying it.

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Billionaire to fund construction of an orbiting optical telescope larger than Hubble

10:42 am

Lazuli
Figure 1 from the proposal paper [pdf].

Schmidt Sciences, a foundation created by one of Google’s founders, announced yesterday it is financing the construction of four new research telescopes, one of which will be an orbiting optical telescope with a mirror 3.1 meters in diameter, larger than the 2.4 meter primary mirror on the Hubble Space Telescope.

Today at a meeting of the American Astronomical Society, Schmidt Sciences, a foundation backed by billionaires Eric and Wendy Schmidt, announced one of the largest ever private investments in astronomy: funding for an orbiting observatory larger than NASA’s Hubble Space Telescope, along with funds to build three novel ground-based observatories. The project aims to have all four components up and running by the end of the decade.

“We’re providing a new set of windows into the universe,” says Stuart Feldman, president of Schmidt Sciences, which will manage the observatory system. Time on the telescopes will be open to scientists worldwide, and data harvested by them will be available in linked databases. Schmidt Sciences declined to say how much it is investing but Feldman says the space telescope, called Lazuli, alone will cost hundreds of millions of dollars.

Eric Schmidt was once CEO of Google, and in recent years has been spending his large fortune (estimated to exceed $50 billion) on space ventures. For example, in March 2025 he acquired control of the rocket startup Relativity.

While the three new ground-based telescopes will do important work, the Lazuli space telescope is by far the most important, not only scientifically but culturally. » Read more

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Detection of the wake of Betelgeuse’s companion star

4:27 pm

The wake of Betelgeuse's companion star

Astronomers believe they have detected evidence of the wake created by Betelgeuse’s companion star as it plows through the primary star’s vast atmosphere.

You can read their paper here [pdf]. The cartoon to the right, annotated by me to post here, is figure 5 of the paper, looking down at Betelgeuse’s pole. It is not to scale. The scientists have nicknamed the companion Siwarha.

The team detected Siwarha’s wake by carefully tracking changes in the star’s light over nearly eight years. These changes show the effects of the previously unconfirmed companion as it plows through the outer atmosphere of Betelgeuse. This discovery resolves one of the biggest mysteries about the giant star, helping scientists to explain how it behaves and evolves while opening new doors to understanding other massive stars nearing the end of their lives.

Located roughly 650 light-years away from Earth in the constellation Orion, Betelgeuse is a red supergiant star so large that more than 400 million Suns could fit inside. Because of its enormous size and proximity, Betelgeuse is one of the few stars whose surface and surrounding atmosphere can be directly observed by astronomers, making it an important and accessible laboratory for studying how giant stars age, lose mass, and eventually explode as supernovae.

Using NASA’s Hubble and ground-based telescopes at the Fred Lawrence Whipple Observatory and Roque de Los Muchachos Observatory, the team was able to see a pattern of changes in Betelgeuse, which provided clear evidence of a long-suspected companion star and its impact on the red supergiant’s outer atmosphere. Those include changes in the star’s spectrum, or the specific colors of light given off by different elements, and the speed and direction of gases in the outer atmosphere due to a trail of denser material, or wake. This trail appears just after the companion crosses in front of Betelgeuse every six years, or about 2,100 days, confirming theoretical models.

Betelgeuse is essentially a giant blob that undulates like a blob of water floating in weightlessness on ISS. Knowing the location and orbit of this companion will help astronomers better understand the central star’s periodic inexplicable changes.

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Hubble images gigantic protoplanetary disk

10:20 am

Largest known protoplanetary disk
Click for original image.

Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken by the Hubble Space Telescope on February 8, 2025, and shows what scientists believe is the largest protoplanetary disk so far measured.

Located roughly 1,000 light-years from Earth, IRAS 23077+6707, nicknamed “Dracula’s Chivito,” spans nearly 400 billion miles — 40 times the diameter of our solar system to the outer edge of the Kuiper Belt of cometary bodies. The disk obscures the young star within it, which scientists believe may be either a hot, massive star, or a pair of stars. And the enormous disk is not only the largest known planet-forming disk; it’s also shaping up to be one of the most unusual.

…The impressive height of these features wasn’t the only thing that captured the attention of scientists. The new images revealed that vertically imposing filament-like features appear on just one side of the disk, while the other side appears to have a sharp edge and no visible filaments. This peculiar, lopsided structure suggests that dynamic processes, like the recent infall of dust and gas, or interactions with its surroundings, are shaping the disk.

You can read the peer-reviewed paper here [pdf]. The structure of this system has left them with more questions than answers. They can’t see the central star due to the dust. They don’t know if any planets exist as yet in the system. They don’t really understand the structural details that they can see.

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Two very different galaxies

9:54 am

Two very different galaxies.
Click for original.

Cool image time! The picture to the right, reduced and sharpened to post here, was released today as the Hubble picture of the week. From the caption:

The trick is that these galaxies are not actually very close. The large blue galaxy MCG-02-05-050 is located 65 million light-years from Earth; its brighter smaller companion MCG-02-05-050a, at 675 million light-years away, is over ten times the distance! Owing to this, MCG-02-05-050a is likely the larger galaxy of the two, and MCG-02-05-050 comparatively small. Their pairing in this image is simply an unlikely visual coincidence.

The smaller blue galaxy, also called Arp 4, has an active nucleus that emits a lot of energy, suggesting the presence of a supermassive black hole. Less is known about the more distant orange galaxy.

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The beginnings of a planetary nebula

9:49 am

Calabash 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 back in 2017 but released this week by NASA’s PR department. It shows what astronomers have nicknamed the Calabash Nebula. From the Wikipedia page:

The Calabash Nebula, also known as the Rotten Egg Nebula or by its technical name OH 231.84 +4.22, is a protoplanetary nebula (PPN) 1.4 light years (13 Pm) long and located some 5,000 light years (47 Em) from Earth in the constellation Puppis. The name “Calabash Nebula” was first proposed in 1989 in an early paper on its expected nebular dynamics, based on the nebula’s appearance.[5] The Calabash is almost certainly a member of the open cluster Messier 46, as it has the same distance, radial velocity, and proper motion.[6] The central star is QX Puppis, a binary composed of a very cool Mira variable and an A-type main-sequence star.

The star in the center is an ancient red giant that is in the initial stages of dying. As it does so it periodically erupts, sending out jets of material from its poles. The result is this elongated shape. According to the release, “the gas shown in yellow is moving close to a million kilometers an hour.”

Over the next few thousand years these eruptions will shape the planetary nebula. Since the central star is actually a binary, those two stars will likely act like the blades in a mixer, adding more interesting forms to the material as it is shot out to form this nebula.

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A small galaxy with lots of massive stars

9:54 am

A small galaxy with many massive 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 and released this week as the European Space Agency’s (ESA) Hubble picture of the week.

This dwarf galaxy, 13 million light years away, is called Markarian 178 (Mrk 178). Though much smaller than the Milky Way, it is packed with massive stars. From the caption:

While the bulk of the galaxy is blue owing to an abundance of young, hot stars with little dust shrouding them, Mrk 178 gets a red hue from a collection of massive stars, which are especially concentrated in the brightest, reddish region near the galaxy’s edge. This azure cloud is home to a large number of rare objects called Wolf–Rayet stars. Wolf–Rayet stars are massive stars that are casting off their atmospheres through powerful winds. Because Mrk 178 contains so many Wolf–Rayet stars, the bright emission lines from these stars’ hot stellar winds are etched upon the galaxy’s spectrum. Particularly ionised hydrogen and oxygen appear as a red colour to Mrk 178 in this photo, observed using some of Hubble’s specialised light filters.

Massive stars enter the Wolf–Rayet phase just before they collapse into black holes or neutron stars. Because Wolf–Rayet stars last for only a few million years, researchers know that something must have triggered a recent burst of star formation in Mrk 178. At first glance, it’s not clear what could be the cause — Mrk 178 doesn’t seem to have any close galactic neighbours that could have stirred up its gas to form new stars. Astronomers believe that it was triggered by the interaction with a smaller satellite, as revealed by the presence of low surface brightness tidal features detected around Mrk 178 in deep imaging acquired with the Large Binocular Telescope.

And yet, these observations do not see this small satellite galaxy. It has either been completely absorbed into Mrk 178, or maybe this theory for explaining this dwarf galaxy’s make-up is flawed.

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New images of interstellar Comet 3I/Atlas

9:56 am

New Hubble image of 3I/Atlas
Click for original.

Juice image of 3I/Atlas
Click for original.

Both NASA and the European Space Agency (ESA) yesterday released new photos of the interstellar comet 3I/Atlas.

First, NASA released the image on the right, taken on November 30, 2025 by the Hubble Space Telescope. At the time the comet was about 178 million miles away. It clearly shows the comet’s coma of material, surrounding a bright nucleus at the center. The streaks are background stars.

Next, the mission team for Europe’s Juice probe, on its way to Jupiter, released one small portion of a picture taken by its navigation camera. That picture is the second to the right.

During November 2025, ESA’s Jupiter Icy Moons Explorer (Juice) used five of its science instruments to observe 3I/ATLAS. The instruments collected information about how the comet is behaving and what it is made of. In addition, Juice snapped the comet with its onboard Navigation Camera (NavCam), designed not as a high-resolution science camera, but to help Juice navigate Jupiter’s icy moons following arrival in 2031.

Though the data from the science instruments won’t arrive on Earth until February 2026, our Juice team couldn’t wait that long. They decided to try downloading just a quarter of a single NavCam image to see what was in store for them. The very clearly visible comet, surrounded by signs of activity, surprised them.

Not only do we clearly see the glowing halo of gas surrounding the comet known as its coma, we also see a hint of two tails. The comet’s ‘plasma tail’ – made up of electrically charged gas, stretches out towards the top of the frame. We may also be able to see a fainter ‘dust tail’ – made up of tiny solid particles – stretching to the lower left of the frame.

The image was taken on 2 November 2025, during Juice’s first slot for observing 3I/ATLAS. It was two days before Juice’s closest approach to the comet, which occurred on 4 November at a distance of about 66 million km.

Because Juice is presently behind the Sun (as seen from Earth), most of the data it collected during its closest approach won’t be downloaded until February. This one partial image is only a fore taste.

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A galaxy with a starburst ring within its nucleus

12:49 pm

A galaxy with a starburst ring
Click for full image.

Cool image time! The picture to the right, cropped, reduced, sharpened, and annotated to post here, was released today by the science team of the Hubble Space Telescope as the picture of the week. This crop focuses on the central regions of this barred spiral galaxy, about 70 million light years away, with an unusual extra feature, a starburst ring encircling its nucleus. From the caption:

NGC 6951’s bar may be responsible for another remarkable feature: a white-blue ring that encloses the very heart of the galaxy. This is called a circumnuclear starburst ring — essentially, a circle of enhanced star formation around the nucleus of a galaxy. The bar funnels gas toward the centre of the galaxy, where it collects in a ring about 3800 light-years across. Two dark dust lanes that run parallel to the bar mark the points where gas from the bar enters the ring.

The dense gas of a circumnuclear starburst ring is the perfect environment to churn out an impressive number of stars. Using data from Hubble, astronomers have identified more than 80 potential star clusters within NGC 6951’s ring. Many of the stars formed less than 100 million years ago, but the ring itself is longer-lived, potentially having existed for 1–1.5 billion years.

This galaxy has also seen about a half dozen supernova, which raises the question: Does intense star formation trigger more supernovae? That is a question that can’t be answered with the data presently available.

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A galaxy sunnyside up

9:23 am

A galaxy sunnyside up
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, is the Hubble picture of the week. It shows a strange galaxy that defies categorization. From the caption:

The galaxy in question is NGC 2775, which lies 67 million light-years away in the constellation Cancer (The Crab). NGC 2775 sports a smooth, featureless centre that is devoid of gas, resembling an elliptical galaxy. It also has a dusty ring with patchy star clusters, like a spiral galaxy. Which is it, then: spiral or elliptical — or neither?

Because we can only view NGC [2775 from one angle, it’s difficult to say for sure. Some researchers have classified NGC 2775 as a spiral galaxy because of its feathery ring of stars and dust, while others have classified it as a lenticular galaxy. Lenticular galaxies have features common to both spiral and elliptical galaxies. It’s not yet known exactly how lenticular galaxies come to be, and they might form in a variety of ways.

To me, the galaxy most resembles a fried egg, sunnyside up, though I very strongly doubt that was the process that formed it. The bright center however suggests that something there has in the past emitted a lot of energy and radiation, thus clearing out the gas and dust from that center.

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The central star-forming cauldron of M82, the most well known star-forming galaxy

12:40 pm

The central star-forming region of M82
Click for original. For original of inset go here.

Cool image time! The picture to the right, cropped, reduced, and annotated to post here, was released today by the Hubble Science team. It shows the central star-forming core of the galaxy M82, only about 12 million light years away and long known as a “peculiar” galaxy by earlier research from the 20th century. For this reason I used the 1963 optical image taken by the 200-inch Hale Telescope at Palomar in California as the inset, showing the entire galaxy. At the time the data only suggested some major energetic events were occurring in the galaxy’s core, as indicated by what looked like filaments shooting out from that core at right angles to the plane of the galaxy.

Data since then, from Hubble and Webb and other space telescopes, have revealed that this galaxy, which some have nicknamed the “Cigar Galaxy”, is forming stars at a prolific rate.

Forming stars 10 times faster than the Milky Way, the Cigar Galaxy is what astronomers call a starburst galaxy. The intense starburst period that grips this galaxy has given rise to super star clusters in the galaxy’s heart. Each of these super star clusters contains hundreds of thousands of stars and is more luminous than a typical star cluster.

The red indicates the dust that permeates the galaxy. The blue comes from the radiation emitted from the clusters near the center, illuminating and ionizing that dust.

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Clumps of dust in a star-forming cluster

12:28 pm

Clumps of dust in a star-forming region
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope as part of a study of the dusty clouds inside star-forming regions. From the caption:

Stars in a star cluster shine brightly blue, with four-pointed spikes radiating from them. The centre shows a small, crowded group of stars while a larger group lies out of view on the left. The nebula is mostly thick, smoky clouds of gas, lit up in blue tones by the stars. Clumps of dust hover before and around the stars; they are mostly dark, but lit around their edges where the starlight erodes them.

This cluster sits inside the Large Magellanic Cloud, about 160,000 million light years away and the largest of the several known dwarf galaxies to orbit the Milky Way. It is the second largest such star-forming region with that dwarf galaxies, and thus is a prime research target for studying the birth of stars.

I especially like this image because of the small dust clouds that sit in the foreground, blobs of material that is slowly being ionized away by the radiation from the stars.

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A baby star and its protoplanetary disk

2:38 pm

A baby star and its protoplanetary disk
Click for originial.

Cool image time! The picture to the right, cropped, rotated, reduced, and sharpened to post here, is the Webb picture of the month from NASA and the European Space Agency (ESA), released today. It shows a baby star about 525 light years away.

IRAS 04302+2247, or IRAS 04302 for short, is a beautiful example of a protostar – a young star that is still gathering mass from its environment – surrounded by a protoplanetary disc in which baby planets might be forming. Webb is able to measure the disc at 65 billion km across – several times the diameter of our Solar System. From Webb’s vantage point, IRAS 04302’s disc is oriented edge-on, so we see it as a narrow, dark line of dusty gas that blocks the light from the budding protostar at its centre. This dusty gas is fuel for planet formation, providing an environment within which young planets can bulk up and pack on mass.

When seen face-on, protoplanetary discs can have a variety of structures like rings, gaps and spirals. These structures can be signs of baby planets that are burrowing through the dusty disc, or they can point to phenomena unrelated to planets, like gravitational instabilities or regions where dust grains are trapped. The edge-on view of IRAS 04302’s disc shows instead the vertical structure, including how thick the dusty disk is. Dust grains migrate to the midplane of the disc, settle there and form a thin, dense layer that is conducive to planet formation; the thickness of the disc is a measure of how efficient this process has been.

The dense streak of dusty gas that runs vertically across this image cocoons IRAS 04302, blotting out its bright light such that Webb can more easily image the delicate structures around it. As a result, we’re treated to the sight of two gauzy nebulas on either side of the disc. These are reflection nebulas, illuminated by light from the central protostar reflecting off of the nebular material.

As this is a baby star, the cones above and below the disk indicate the original spherical cloud, with the upper and lower halves now being pulled downward into a spinning disk, where the solar system is forming.

This image is not simply an infrared Webb image. The Hubble Space Telescope provided the optical view, which the Atacama Large Millimetre/submillimetre Array (ALMA) in Chile provided data in those wavelengths. Note also the many background galaxies. The universe is not only infinite, it is infinitely populated.

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Colorful spiral galaxy

9:25 am

A colorful spiral galaxy
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 survey of nineteen nearby galaxies. The galaxy, NGC 2835 and 35 million light years away, has been imaged many times in the past, but the new image contacts new wavelength data designed to identify nebulae. From the caption:

This image differs from previously released images because it incorporates new data from Hubble that captures a specific wavelength of red light called H-alpha. The regions that are bright in H-alpha emission can be seen along NGC 2835’s spiral arms, where dozens of bright pink nebulae appear like flowers in bloom. Astronomers are interested in H-alpha light because it signals the presence of several different types of nebulae that arise during different stages of a star’s life. Newborn massive stars create nebulae called H II regions that are particularly brilliant sources of H-alpha light, while dying stars can leave behind supernova remnants or planetary nebulae that can also be identified by their H-alpha emission.

Compare this image with the 2020 photo. The spiral arms are now alive with red and blue features not seen previously.

This survey hopes to find 50,000 nebula in the galaxies being observed.

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New Hubble observations of Comet 3I/Atlas refine its size

10:42 am

3I/Atlas as seen by Hubble on July 21, 2025
Click for original image.

Using the Hubble Space Telescope, astronomers have refined significantly the size of the interstellar object Comet 3I/Atlas as it zips through the solar system in its journey through the galaxy.

The image to the right, cropped and reduced to post here, is a Hubble image taken on July 21, 2025. The streaks are background stars.

Hubble’s observations allow astronomers to more accurately estimate the size of the comet’s solid, icy nucleus. The upper limit on the diameter of the nucleus is 3.5 miles (5.6 kilometers), though it could be as small as 1,000 feet (320 meters) across, researchers report. Though the Hubble images put tighter constraints on the size of the nucleus compared to previous ground-based estimates, the solid heart of the comet presently cannot be directly seen, even by Hubble.

…Hubble also captured a dust plume ejected from the Sun-warmed side of the comet, and the hint of a dust tail streaming away from the nucleus. Hubble’s data yields a dust-loss rate consistent with comets that are first detected around 300 million miles from the Sun. This behavior is much like the signature of previously seen Sun-bound comets originating within our solar system.

In other words, though this object comes from far outside our solar system, it so far appears to closely resemble comets from our own system. If confirmed, this fact is quite significant, as it suggests the formation of solar systems throughout the galaxy are likely to be relatively similar to our own.

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Galaxies without end

8:55 am

Galaxies without end
Click for original.

Cool image time! The picture to the right, reduced and enhanced to post here, was taken by the Hubble Space Telescope as part of a monitoring program studying the two supernovae that have occurred in this galaxy previously.

Hubble has turned its attention toward NGC 1309 several times; previous Hubble images of this galaxy were released in 2006 and 2014. Much of NGC 1309’s scientific interest derives from two supernovae, SN 2002fk in 2002 and SN 2012Z in 2012. SN 2002fk was a perfect example of a Type Ia supernova, which happens when the core of a dead star (a white dwarf) explodes.

SN 2012Z, on the other hand, was a bit of a renegade. It was classified as a Type Iax supernova: while its spectrum resembled that of a Type Ia supernova, the explosion wasn’t as bright as expected. Hubble observations showed that in this case, the supernova did not destroy the white dwarf completely, leaving behind a ‘zombie star’ that shone even brighter than it did before the explosion. Hubble observations of NGC 1309 taken across several years also made this the first time the white dwarf progenitor of a supernova has been identified in images taken before the explosion.

The image however carries a far more philosophic component. Except for the star near the top (identified by the four diffraction spikes), every single dot and smudge you see in this picture is a galaxy. NGC 1309 is about 100 million light years away, but behind it along its line of sight and at much greater distances are innumerable other galaxies, so many it is impossible to count them. And each is roughly comparable in size to our own Milky Way galaxy, containing billions of stars.

The scale of the universe is simply impossible to grasp, no matter how hard we might try.

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First Hubble images of interstellar comet 3I/Atlas released

5:03 pm

Comet 3I/Atlas, taken by Hubble
Click for original.

An undergraduate student has just released the first pictures taken by the Hubble Space Telescope of the interstellar object 3I/Atlas, confirming that it is a comet as indicated by the earlier image taken by the Gemini North telescope.

One of those images, taken only hours ago, is the inset on the map showing the comet’s route through the solar system to the right. The streaks on the image are either stars or cosmic rays. Though this image is of significantly lower quality than the Gemini North picture, it once again shows both the comet’s nucleus and developing coma.

A preprint [pdf] of a new research paper based on data from both telescopes further confirms this conclusion:

[T]hese results suggest that 3I/ATLAS hosts a coma containing large water ice grains, and that its dust continuum is stable over at least week-long timescales. The spectral characteristics further distinguish 3I from known ultrared trans-Neptunian objects and align it more closely with active Jupiter-family comets.

The last conclusion is very significant. Though the path and speed of this interstellar object says it must come from beyond the solar system, its cometary make-up more resembles comets that reside in the inner solar system. These facts strongly imply that there is at least one other solar systems not very different from our own.

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A galaxy surrounded by galaxies

11:12 am

A galaxy surrounded by galaxies
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 survey of galaxies where Type 1a supernovae have occurred, in order to better refine the precise brightness of these explosions.

What makes this galaxy most interesting are the hundreds of other galaxies that appear to surround it. And that ain’t an illusion.

NGC 3285B is a member of the Hydra I cluster, one of the largest galaxy clusters in the nearby Universe. Galaxy clusters are collections of hundreds to thousands of galaxies that are bound to one another by gravity. The Hydra I cluster is anchored by two giant elliptical galaxies at its centre. Each of these galaxies is about 150,000 light-years across, making them about 50% larger than our home galaxy, the Milky Way. NGC 3285B sits on the outskirts of its home cluster, far from the massive galaxies at the centre.

As for the survey program, Type 1a supernovae are the measure cosmologists have used to discover the unexpected acceleration of the universe’s expansion rate at the largest scales, something they dub “dark energy” because they really don’t understand what they have discovered. That discovery however hinges entirely on the assumed intrinsic brightness of Type 1a supernovae. Astronomers have assumed these supernovae all have the same approximate brightness, and extrapolate their distance by that brightness.

The problem are the assumptions. We really don’t know if all Type 1a supernovae are approximately the same brightness. And even if they are equally bright, we also do not have a firm grasp of what that brightness should be.

This survey is an attempt to narrow or eliminate these uncertainties.

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