Tag: Hubble Space Telescope

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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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
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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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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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Jupiter’s Great Red Spot appears to jiggle like Jello on a 90-day cycle

9:07 am

Jupiter as seen by Hubble over time
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Using the Hubble Space Telescope to photograph Jupiter’s Great Red Spot repeatedly over a four month period from December 2023 to March 2024 scientists have detected a 90-day cycle in which the spot oscillated in shape, shaking like Jello.

“While we knew its motion varies slightly in its longitude, we didn’t expect to see the size oscillate. As far as we know, it’s not been identified before,” said Amy Simon of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, lead author of the science paper published in The Planetary Science Journal. “This is really the first time we’ve had the proper imaging cadence of the GRS. With Hubble’s high resolution we can say that the GRS is definitively squeezing in and out at the same time as it moves faster and slower. That was very unexpected, and at present there are no hydrodynamic explanations.”

The four images to the right are some of those observations. For a full movie showing the changes over ninety days, go here.

The scientists also predict that though the spot has been shrinking for decades, they expect that shrinkage to stop once the spot size no longer extends beyond the jet stream band within which it sits. At that point the different jet streams in the upper and lower bands will hold the spot in place and its size will stabilize.

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The jet 3,000 light years long that causes nearby stars to explode

10:48 am

The jet from M87
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Cool image time! The picture to the left, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope of the giant eliptical galaxy M87, known for more than a century by astronomers for the jet of gas that points outward from its center. Astronomers now know that this jet is produced by a supermassive black hole in the center of M87, weighing 6.5 billion times the mass of our Sun.

The blowtorch-like jet seems to cause stars to erupt along its trajectory. These novae are not caught inside the jet, but are apparently in a dangerous neighbourhood nearby. During a recent 9-month survey, astronomers using Hubble found twice as many of these novae going off near the jet as elsewhere in the galaxy. The galaxy is the home of several trillion stars and thousands of star-like globular star clusters.

M87 is considered an old galaxy, but its entire formation process remains uncertain.

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Webb takes an infrared look at a galaxy looked at by Hubble

12:21 pm

Comparing Hubble with Webb
For original images go here and here.

Cool image time! The bottom picture on the right, cropped to post here, is a just released false color infrared image of the galaxy Arp 107, taken by the Webb Space Telescope. The picture at the top is a previously released optical image taken by the Hubble Space Telescope and featured as a cool image back in September 2023. The Hubble image was taken as part of a survey project to photograph the entire Arp catalog of 338 “peculiar galaxies,” put together by astronomer Halton Arp in 1966. In this case Arp 107 is peculiar because it is actually two galaxies in the process of merging. It is also peculiar because the galaxy on the left has an active galactic nuclei (AGN), where a supermassive black hole is sucking up material and thus emitting a lot of energy.

The Webb infrared image was taken to supplement that optical image. The blue spiral arms indicate dust and star-forming regions. The bright orange object in the center of the galaxy is that AGN, clearly defined by Webb’s infrared camera.

When I posted the Hubble image in 2023, I noted that “if you ignore the blue whorls of the left galaxy, the two bright cores of these merging galaxies are about the same size.” In the Webb image the two cores still appear about the same size, but in the infrared they produce emissions in decidedly different wavelengths, as shown by the different false colors of orange and blue. The core of the galaxy on the right is dust filled and forming stars, while the core of the left galaxy appears to have less dust with all of its emissions resulting from the energy produced by the material being pulled into the supermassive black hole.

The universe is very active and changing, but to understand that process we humans have to look at everything across the entire electromagnetic spectrum, not just in the optical wavelengths our eyes see.

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What the Milky Way would look like if it was presently a star forming powerhouse

9:15 am

A galaxy as seen by Hubble and Webb
For the original images go here and here.

Cool image time! The two pictures to the right, taken respectively by the Hubble and Webb space telescopes of the same galaxy, shows us many different features of a barred galaxy, located about 35 million light years away. From the caption for the Hubble image:

This picture is composed of a whopping ten different images taken by the Hubble Space Telescope, each filtered to collect light from a specific wavelength or range of wavelengths. It spans Hubble’s sensitivity to light, from ultraviolet around 275 nanometres through blue, green and red to near-infrared at 1600 nanometres. This allows information about many different astrophysical processes in the galaxy to be recorded: a notable example is the red 656-nanometre filter used here. Hydrogen atoms which get ionised can emit light at this particular wavelength, called H-alpha emission. New stars forming in a molecular cloud, made mostly of hydrogen gas, emit copious amounts of ultraviolet light which is absorbed by the cloud, but which ionises it and causes it to glow with this H-alpha light.

Therefore, filtering to detect only this light provides a reliable means to detect areas of star formation (called H II regions), shown in this image by the bright red and pink colours of the blossoming patches filling NGC 1559’s spiral arms.

The Z-shaped blue indicates the stars and its most distinct spiral arms. Astronomers presently believe that the Milky Way is also a barred spiral like this, though its star-forming regions are thought to be far less extensive and distinct.

The Webb infrared image matches the Hubble data, with the false color blue indicating the near-infrared and the false color red the mid-infrared. As with the Hubble picture, the red indicates the galaxy’s extensive star forming regions.

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Mars loses hydrogen at very different rates, depending on the planet’s distance from the Sun

11:37 am

Hubble uv images of Mars atmosphere
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Scientists using data from both the MAVEN Mars Orbiter and the Hubble Space Telescope have determined that the rate in which Mars loses hydrogen and deuterium varies considerably during the Martian year, with the rate going up rapidly when the red planet reaches its closest point to the Sun. The picture to the right, reduced to post here, shows the data from Hubble.

These are far-ultraviolet Hubble images of Mars near its farthest point from the Sun, called aphelion, on December 31, 2017 (top), and near its closest approach to the Sun, called perihelion, on December 19, 2016 (bottom). The atmosphere is clearly brighter and more extended when Mars is close to the Sun.

Reflected sunlight from Mars at these wavelengths shows scattering by atmospheric molecules and haze, while the polar ice caps and some surface features are also visible. Hubble and NASA’s MAVEN showed that Martian atmospheric conditions change very quickly. When Mars is close to the Sun, water molecules rise very rapidly through the atmosphere, breaking apart and releasing atoms at high altitudes.

From this data scientists will be better able to map out the overall loss rate of water on Mars over many billions of years.

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A galaxy with a halo and a stupendous central black hole

9:22 am

A galaxy with a halo and a stupendous black hole
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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 that have what astronomers call active galactic nuclei (AGNs). This galaxy, dubbed IC 4709, is about 240 million light years away.

If IC 4709’s core were just filled with stars, it would not be nearly so bright. Instead it hosts a gargantuan black hole, 65 million times the mass of our Sun. A disc of gas spirals around and eventually into this black hole, with the gas crashing together and heating up as it spins. It reaches such high temperatures that it emits vast quantities of electromagnetic radiation, from infrared to visible to ultraviolet light and beyond — in this case including X-rays. The AGN in IC 4709 is obscured by a lane of dark dust, just visible at the centre of the galaxy in this image, which blocks any optical emission from the nucleus itself.

To get a very vague sense of scale, this supermassive black hole is more than sixteen times more massive than the relatively inactive supermassive black hole in the center of the Milky Way. This imagery and data from Hubble will help astronomers better understand the interaction between the black hole and its surrounding galaxy.

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A real whirlpool in space

9:52 am

A real whirlpool in space
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Cool image time! The picture above, cropped to post here, was taken by the Hubble Space Telescope as part of a survey of nearby galaxies that have what astronomers call an Active Galactic Nuclei (AGN), because the supermassive black hole at the center is devouring nearby material at a great rate and thus producing high energy emissions as it does so.

Many active galaxies are known to astronomers at vast distances from Earth, thanks to the great brightness of their nuclei highlighting them next to other, dimmer galaxies. At 128 million light-years from Earth, UGC 3478 is positively neighbourly to us. The data used to make this image comes from a Hubble survey of nearby powerful AGNs found in relatively high-energy X-rays, like this one, which it is hoped can help astronomers to understand how the galaxies interact with the supermassive black holes at their hearts.

The bottom line is that this spiral galaxy literally is a whirlpool, the entire galaxy spiralling down into that massive black hole in its center. One cannot help wondering why such galaxies don’t end up eventually getting completely swallowed by that black hole.

Or maybe they do, and we don’t see such things because all that is left is a supermassive black hole that emits no light or energy at all, a dark silent ghost traveling between the galaxies unseen and undetectable.

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New data continues to refine the margin of error for the Hubble constant

9:45 am

The uncertainty of science: New data using the Webb Space Telescope’s spectroscopic capabilities has provided a more refined measure of the expansion rate of the universe, dubbed the Hubble constant.

According to previous research, that rate could be anywhere from 67.4 to 73.2 kilometers per second per megaparsecs, depending on whether you rely on data from the Planck orbiter or that of the Hubble Space Telescope. Though this difference appears reasonable considering the uncertainties and assumptions that go into research that determines both numbers, astronomers have been unhappy with the difference. The numbers should match and they don’t.

Now new data from Webb suggests this difference really is nothing more than the margin of error caused by the many uncertainties and assumptions involved. That new Webb data measured the Hubble constant using three different methods, all similar to that used by Hubble, and came up with 67.85, 67.96, and 72.04, all in the middle of the previous two numbers from Hubble and Planck.

In other words, all the data is beginning to fall within this margin of error.

Astronomers are without doubt still going to argue about this, but it does appear that the research is beginning to coalesce around an approximate number. More important, in terms of cosmology these results confirm the theory that the expansion of the universe is accelerating (dubbed “dark energy” simply because it needs a name), since they confirm the method used to measure that expansion rate in the very distant universe.

Keep your minds open however. There remain many questions and uncertainties with all these conclusions. Nothing is settled, nor will it be likely for decades if not centuries.

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A galaxy with a ring

9:34 am

A galaxy with a ring
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Cool image time! The photo to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope, and appears part of a long term survey of nearby ringed galaxies. From the caption:

MCG+07-07-072 has quite an unusual shape, for a spiral galaxy, with thin arms emerging from the ends of its barred core to draw a near-circle around its disc. It is classified, using a common extension of the basic Hubble scheme, as an SBc(r) galaxy: the c denotes that its two spiral arms are loosely wound, each only performing a half-turn around the galaxy, and the (r) is for the ring-like structure they create. Rings in galaxies come in quite a few forms, from merely uncommon, to rare and astrophysically important!

Lenticular galaxies are a type that sit between elliptical and spiral galaxies. They feature a large disc, unlike an elliptical galaxy, but lack any spiral arms. Lenticular means lens-shaped, and these galaxies often feature ring-like shapes in their discs. Meanwhile, the classification of “ring galaxy” is reserved for peculiar galaxies with a round ring of gas and star formation, much like spiral arms look, but completely disconnected from the galactic nucleus – or even without any visible nucleus! They’re thought to be formed in galactic collisions.

This galaxy is about 320 million light years away, and is also known as Abell 426. Though astronomers think that these various shapes of galaxies, from barred to lenticular to ringed, are formed from a variety of galactic collusions and interactions with each galaxy’s nucleus, that remains nothing more than an educated guess. The complexity of galaxy evolution, involving billions of years and millions of stars, is barely in its infancy, and requires a lot of assumptions because our observations only involves a mere nanosecond in that grand history.

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A supernova overpowers a spiral galaxy

9:34 am

A supernova overwhelms a small galaxy

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken in early 2023 by the Hubble Space Telescope because a ground-based automated sky survey had detected a new supernovae in late 2022 in this galaxy. The spiral galaxy is dubbed LEDA 857074, and is interesting because of its bright central bar and dim and broken spiral arms.

That supernova is the bright spot inside the galaxy’s central bar. It is so bright that it almost looks like someone accidently pasted a white dot there using a graphics program. From the caption:

Astronomers have catalogued millions of galaxies, so while today tens of thousands of supernovae are detected annually, the chance that one is spotted in any particular galaxy is slim. We also do not know how actively LEDA 857074 is forming stars, and therefore how often it might host a supernova. This galaxy is therefore an unlikely and lucky target of Hubble, thanks to this supernova shining a spotlight on it! It now joins the ranks of many more famous celestial objects, with its own Hubble image.

The galaxy itself had been studied by almost no one until this supernova was discovered in it.

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A classic spiral galaxy

8:53 am

A classic spiral galaxy
Click for original image.

Monday is always a slow news day in space, so we start the day with a cool image. The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope of a spiral galaxy about 100 million light years from Earth.

That NGC 3430 is such a fine example of a galactic spiral may be why it ended up as part of the sample that Edwin Hubble used to define his classification of galaxies. Namesake of the Hubble Space Telescope, in 1926 he authored a paper which classified some four hundred galaxies by their appearance — as either spiral, barred spiral, lenticular, elliptical or irregular. This straightforward typology proved immensely influential, and the modern, more detailed schemes that astronomers use today are still based on it. NGC 3430 itself is an SAc galaxy, a spiral lacking a central bar with open, clearly-defined arms.

The bright blue indicates areas of star formation, while the reddish streaks indicates dust. The orange/reddish dots above and below the galaxy are distant background galaxies whose light has been shifted to the red because they appear to be moving away from us due to the expansion rate of the universe.

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A blob in space

9:47 am

A blob in space
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope of the dwarf galaxy NGC 5238.

Its unexciting, blob-like appearance, resembling more an oversized star cluster than a galaxy, belies a complicated structure which has been the subject of much research by astronomers. Here, the NASA/ESA Hubble Space Telescope is able to pick out the galaxy’s countless stars, as well as its associated globular clusters — the glowing spots both inside and around the galaxy that are swarmed by yet more stars.

NGC 5238 is theorised to have recently — here meaning no more than a billion years ago! — had a close encounter with another galaxy. The evidence for this is the tidal distortions of NGC 5238’s shape, the kind produced by two galaxies pulling on each other as they interact. There’s no nearby galaxy which could have caused this disturbance, so the hypothesis is that the culprit is a smaller satellite galaxy that was devoured by NGC 5238.

Astronomers are hoping to use this image to detect the two different populations of stars within this blob that come from those once interacting galaxies.

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A penguin and egg, as seen by Webb and Hubble

11:32 am

A penquin and egg compared
Click for original images.

Cool image time! The two pictures to the right, cropped, reduced, and sharpened to post here, were taken by both the Webb and Hubble space telescopes of the same unusual galactic object, officially called Arp 142 but nicknamed by astronomers the Penquin and the Egg.

Both of these objects are galaxies. The Penquin’s strange shape is caused by the presence of the Egg, which is an elliptical galaxy that is twisting and distorting the Penquin’s original spiral galaxy whirlpool as it flies past. From the caption:

Like all spiral galaxies, the Penguin is still very rich in gas and dust. The galaxies’ “dance” gravitationally pulled on the Penguin’s thinner areas of gas and dust, causing them to crash in waves and form stars. Look for those areas in two places: what looks like a fish in its “beak” and the “feathers” in its “tail.”

Surrounding these newer stars is smoke-like material that includes carbon-containing molecules, known as polycyclic aromatic hydrocarbons, which Webb is exceptional at detecting. Dust, seen as fainter, deeper orange arcs also swoops from its beak to tail feathers.

In contrast, the Egg’s compact shape remains largely unchanged. As an elliptical galaxy, it is filled with aging stars, and has a lot less gas and dust that can be pulled away to form new stars. If both were spiral galaxies, each would end the first “twist” with new star formation and twirling curls, known as tidal tails.

Another reason for the Egg’s undisturbed appearance: These galaxies have approximately the same mass or heft, which is why the smaller-looking elliptical wasn’t consumed or distorted by the Penguin.

The differences between the two pictures also reveal many aspects of the Penguin. The Hubble optical image at the top captures the lanes of dust in the foreground, while the Webb infrared image at the bottom looks right through this dust to better trace the now-distorted spiral arms where star formation is presently taking place.

Astronomers estimate that these two galaxies are about 100,000 light years apart, comparable to the width of the Milky Way. In comparison, the Andromeda galaxy is around 2.5 million light years away, and will not begin interacting with our galaxy in this manner for an estimated four billion years. The Egg and Penguin however began their warped dance about 50 million years ago.

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Astronomers: A black hole weighing 8,200 solar masses likely sits at the center of the Milky Ways’ largest globular cluster

2:39 pm

Omega Centauri
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By analyzing the motion of seven fast moving stars at the center of the globular cluster Omega Centauri, the largest such cluster in the Milky Way and located about 18,000 light years away, astronomers now think they have detected evidence of an intermediate-sized black hole weight at least 8,200 solar masses.

You can read the published paper here. [pdf] The picture of Omega Centauri to the right, reduced and sharpened to post here, was created from more than 500 images taken over two decades by the Hubble Space Telescope. The inset, figure 1b of the paper, shows those seven fast-moving stars in pink, each having an arrow indicating the distance they are expected to move in a 100 years. The dashed circle marks the region where the black hole is believed to reside, with the dark blue cross in its upper left quadrant the most likely position of the black hole based on calculations.

From the caption for the larger Omega Centauri Hubble image:

Omega Centauri is visible from Earth with the naked eye and is one of the favourite celestial objects for stargazers in the southern hemisphere. Although the cluster is 17 700 light-years away, lying just above the plane of the Milky Way, it appears almost as large as the full Moon when seen from a dark rural area.

Though such intermediate-sized black holes have been theorized as existing inside globular clusters, I think this is the first real evidence of one.

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Can you spot the supernova?

9:53 am

Supernova 2022zut
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken using the Hubble Space Telescope and was done as part of a larger research project studying what astronomers call Type 1a supernovae.

NGC 3810, the galaxy featured in this image, was the host of a Type Ia supernova in 2022. In early 2023 Hubble focused on this and a number of other galaxies to closely examine recent Type Ia supernovae. This kind of supernova results from a white dwarf exploding, and they all have a very consistent brightness. That allows them to be used to measure distances: we know how bright a Type Ia supernova should be, so we can tell how far away it must be from how dim it appears.

One uncertainty in this method is that intergalactic dust in between Earth and a supernova blocks some of its light. How do you know how much of the reduction in light is caused by distance, and how much by dust? With the help of Hubble, there’s a clever workaround: take images of the same Type Ia supernovae in ultraviolet light, which is almost completely blocked by dust, and in infrared light, which passes through dust almost unaffected. By carefully noting how much light comes through at each wavelength, the relationship between supernova brightness and distance can be calibrated to account for dust. Hubble can observe both these wavelengths of light in great detail with the same instrument. That makes it the perfect tool for this experiment, and indeed, some of the data used to make this beautiful image of NGC 3810 were focused on its 2022 supernova. You can see it as a point of light just below the galactic nucleus, or in the annotated image here.

Can you spot the supernova? If you can’t without checking the annotated or original image, don’t be disappointed. It is there but hard to distinguish unless you know where to look.

This supernova however does illustrate the advances in astronomical observational capabilities in the past two decades, resulting not from the giant big ground-based telescopes that cost a fortune and take decades to build nor from the space telescopes like Hubble and Webb that get all the press. These new capablities come from sophisticated smaller telescopes designed to do daily surveys of the entire sky, combined with software that can quickly compare images each day and identify anything that changed.

For example, this 2022 supernova was the 18,142nd discovered that year. That total exceeds the entire number of supernovae that had been discovered in all history prior to this century.

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Scientists release first image from Hubble in one-gyro mode

9:29 am

First Hubble image in one-gyro mode
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The Hubble science team today released the first image from the Hubble Space Telescope produced in its new one-gyro mode.

That image it so the right, cropped, reduced, and sharpened to post here, and shows NGC 1546, a nearby galaxy in the constellation Dorado about 52 million light years away. The inset shows at full resolution the small red galaxy near the top, to give some sense of the telescope’s capabilities in this one-gyro mode.

The details astonish me, and prove my pessimism about this new mode to have been wrong. I expected future images to be more fuzzy, with Hubble’s ability to take sharp images largely limited. The resolution here is excellent, and bodes well for future science observations.

Nonetheless, the telescope is still working under major limitations:

Although one-gyro mode is an excellent way to keep Hubble science operations going, it does have limitations, which include a small decrease in efficiency (roughly 12 percent) due to the added time required to slew and lock the telescope onto a science target.

As previously noted, prior to the use of the fine guidance sensors, fixed head star trackers position Hubble’s pointing closer to the target. If Earth or the moon block two of the fixed head star trackers’ fields of view, Hubble must move further along in its orbit until the star trackers can see the sky and its stars again. This process encroaches upon science observation time. Second, the additional time the fine guidance sensors take to further search for the guide stars adds to the total time the sensors use to complete the acquisition.

Third, in one-gyro mode Hubble has some restrictions on the science it can do. For example, Hubble cannot track moving objects that are closer to Earth than the orbit of Mars. Their motion is too fast to track without the full complement of gyros. Additionally, the reduced area of sky that Hubble can point to at any given time also reduces its flexibility to see transient events or targets of opportunity like an exploding star or an impact on Jupiter.

When combined, these factors may yield a decrease in productivity of roughly 20 to 25 percent from the typical observing program conducted in the past using all three gyros.

It really is time for the astronomical community to get its act together and begin work on developing and launching more large optical telescopes into space. Hubble has shown us the potential of in-space optical astronomy. That astronomers have not flocked in the last three decades to build more such telescopes is puzzling beyond belief.

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Hubble goes to one-gyro mode, limiting the telescope’s observational capabilities; NASA rejects private repair mission

9:59 am

Story Musgrave on the shuttle robot arm during the last spacewalk of the 1993 Hubble repair mission
Story Musgrave on the shuttle robot arm during
the last spacewalk of the 1993 Hubble repair mission

After the third safe mode event in six months, all caused by issues with the same gyroscope, engineers have decided to shift the Hubble Space Telescope to what they call one-gyro mode, whereby the telescope is pointed using only one gyroscope, and the remaining working gyro is kept in reserve.

The spacecraft had six new gyros installed during the fifth and final space shuttle servicing mission in 2009. To date, three of those gyros remain operational, including the gyro currently experiencing problems, which the team will continue to monitor. Hubble uses three gyros to maximize efficiency but can continue to make science observations with only one gyro. NASA first developed this plan more than 20 years ago, as the best operational mode to prolong Hubble’s life and allow it to successfully provide consistent science with fewer than three working gyros. Hubble previously operated in two-gyro mode, which is negligibly different from one-gyro mode, from 2005-2009. One-gyro operations were demonstrated in 2008 for a short time with no impact to science observation quality.

While continuing to make science observations in one-gyro mode, there are some expected minor limitations. The observatory will need more time to slew and lock onto a science target and won’t have as much flexibility as to where it can observe at any given time. It also will not be able to track moving objects closer than Mars, though these are rare targets for Hubble.

This NASA press release is carefully spun to hide the simple fact that in one-gyro mode, the telescope will simply not be able to take sharp pictures. » Read more

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Hubble once again in safe mode due to gyro problem

10:23 am

On May 24, 2024 the Hubble Space Telescope once again paused its science operations and entered in safe mode, apparently due to gyroscope problem.

The telescope automatically entered safe mode when one of its three gyroscopes gave faulty telemetry readings. Hubble’s gyros measure the telescope’s slew rates and are part of the system that determines and controls precisely the direction the telescope is pointed. NASA will provide more information early the first week of June.

It is not clear if this is the same gyroscope that caused the last two safe mode events.

With each such event the telescope gets closer and closer to having only two gyroscopes. At that point it will shift to one-gyro mode, using only one and holding the second in reserve. From then on it will no longer be able to take perfectly sharp pictures. Science will still be possible, but not like before.

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Visiting a galactic bar

9:27 am

Visiting a galactic bar
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 research project studying the flow of gases inside barred galaxies. It shows a spiral galaxy, NGC 4731, edge on, located about 43 million light years away. From the caption:

Barred spiral galaxies outnumber both regular spirals and elliptical galaxies put together, numbering around 60% of all galaxies. The visible bar structure is a result of orbits of stars and gas in the galaxy lining up, forming a dense region that individual stars move in and out of over time. This is the same process that maintains a galaxy’s spiral arms, but it is somewhat more mysterious for bars: spiral galaxies seem to form bars in their centres as they mature, accounting for the large number of bars we see today, but can also lose them later on as the accumulated mass along the bar grows unstable. The orbital patterns and the gravitational interactions within a galaxy that sustain the bar also transport matter and energy into it, fuelling star formation.

Astronomers don’t really understand why these barred structures develop, since you would expect the overall gravity of the galaxy would promote a spiral or spherical shape. There must are factors not yet understood or completely identified (such as the magnetic fields of such galaxies).

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NASA versus Isaacman/SpaceX on upgrading Hubble

12:19 pm

Link here. The NPR article is a long detailed look at NASA on-going review of the proposal by billionaire astronaut Jared Isaacman and SpaceX to to do a maintenance mission to the Hubble Space Telescope.

The NPR spin is subtly hostile to the mission, because it would be funded privately and run entirely by private citizens, not the government. Like all modern leftist news outlets, it can only imagine the government capable of doing such things properly.

Reading between the lines, however, what I instead sense is that NASA and the scientific community is generally quite enthusiastic about this proposal, but wants to make sure it not only is done safely but does nothing to harm Hubble in any way, both completely reasonable concerns. While there appear to be some individuals who are opposed for purely political and egotistically reasons — a desire to keep control of this turf no matter what — I don’t see that faction having much influence long term.

Whether this project can go forward I think will be largely determined by the success or failure of Isaacman’s next manned flight, dubbed Polaris Dawn and scheduled for this summer. On it he will attempt the first spacewalk by a private citizen, using SpaceX’s Resilience capsule and EVA spacesuit. If that spacewalk is a success, and he can demonstrate the ability to accomplish some complex tasks during the EVA, it will certainly ease the concerns of many about a follow-up repair mission to Hubble.

If it does proceed, the goal appears to be to attach new gyroscope hardware to the outside of Hubble, rather than replace the failed gyroscopes already in place. Such an approach will be simpler and more in line with the capabilities of a Dragon capsule, compared to the repair work the astronauts did on the space shuttle.

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A galaxy’s net of dust

10:02 am

A galaxy's net of dust
Click for full image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope of the central part of galaxy NGC 4753, 60 million light years away and known as a lenticular galaxy because of its elongated elliptical shape and ill-defined spiral arms. It is believed we looking at this galaxy edge-on.

You can see a wider image of NGC 4753 here, released in January and taken by the Gemini South telescope in Chile. According to that press release, the brown dust lanes that seem to form a wavy net in the foreground are created by a process called differential precession:

Precession occurs when a rotating object’s axis of rotation changes orientation, like a spinning top that wobbles as it loses momentum. And differential means that the rate of precession varies depending on the radius. In the case of a dusty accretion disk orbiting a galactic nucleus, the rate of precession is faster toward the center and slower near the edges. This varying, wobble-like motion results from the angle at which NGC 4753 and its former dwarf companion collided and is the cause of the strongly twisted dust lanes we see wrapped around the galaxy’s luminous nucleus today.

Once again, the limitation of only observing this object from one angle makes it very difficult to untangle what it really looks like. Therefore, these conclusions carry a great deal of uncertainty.

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A supernova factory

9:44 am

A supernova factory

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope in 2023 as part of a survey of galaxies where recent supernovae have occurred. One occurred in 2020 in this galaxy, which is about 240 million light years away and dubbed UGC 9684.

Remarkably, the 2020 supernova in this galaxy isn’t the only one that’s been seen there — four supernova-like events have been spotted in UGC 9684 since 2006, putting it up there with the most active supernova-producing galaxies. It turns out that UGC 9684 is a quite active star-forming galaxy, calculated as producing one solar mass worth of stars every few years! This level of stellar formation makes UGC 9684 a veritable supernova factory, and a galaxy to watch for astronomers hoping to examine these exceptional events.

This image provides scientists a high resolution baseline should another supernova occur. It will not only make it easier to spot a future supernova, it also increases the chances that the progenitor star that went boom could be identified.

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Hubble out of safe mode and resumed science observations

8:43 am

According to the Hubble website, engineers have corrected the gyro issue that put the Hubble Space Telescope into safe mode on April 23, 2024.

On April 30, 2024, NASA announced it restored the agency’s Hubble Space Telescope to science operations April 29. The spacecraft is in good health and once again operating using all three of its gyros. All of Hubble’s instruments are online, and the spacecraft has resumed taking science observations.

No other information was released. The safe mode was initiated by faulty readings from one of those gyros. Was the problem in the gyro itself, or were the readings merely incorrect? This matters because when one of those gyros finally fails, the telescope will go to one-gyro mode, saving its second gyro in reserve. At that point Hubble will no longer be able to take sharp images, though it will still be able to some science.

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Webb takes an infrared look at the mane of the Horsehead Nebula

10:01 am

Context images
Click for original image.

The mane of the Horsehead Nebula, seen in infrared
Click for original image.

The cool infrared image to the right, cropped, reduced, and sharpened to post here, was taken by the Webb Space Telescope and released today. The three pictures above provide the context, with the rectangle inside the rightmost image indicated the area covered by the close-up to the right.

Webb’s new images show part of the sky in the constellation Orion (The Hunter), in the western side of a dense region known as the Orion B molecular cloud. Rising from turbulent waves of dust and gas is the Horsehead Nebula, otherwise known as Barnard 33, which resides roughly 1,300 light-years away.

The nebula formed from a collapsing interstellar cloud of material, and glows because it is illuminated by a nearby hot star. The gas clouds surrounding the Horsehead have already dissipated, but the jutting pillar is made of thick clumps of material and therefore is harder to erode. Astronomers estimate that the Horsehead has about five million years left before it too disintegrates. Webb’s new view focuses on the illuminated edge of the top of the nebula’s distinctive dust and gas structure.

In the close-up, note the many distant tiny galaxies, both above the mane as well as glowing throught it.

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