Tag: Hubble

The future of astronomy, as seen by PBS News in 1991

6:01 pm

An evening pause: Today is the 75th anniversary of the moment astonomers took the lens cap off the Hale Telescope at Palomar, what astronomers call “first light.” In honor of this anniversary, tonight’s evening pause is a somewhat well-done news piece produced by PBS in 1991, describing the state of ground-based astronomy at that time, which was actually another key moment in the history of astronomy. After decades of no advancement following the Hale telescope, the field was about to burst out with a whole new set of telescopes exceeding it significantly, based on new technologies. We today have become accustomed to those new telescopes, but in 1991 they were still incomplete or on the drawing board.

This was also after the launch of Hubble but before it was fixed, so this moment was also a somewhat dark time for astronomy in general. Watching this news piece gives you a sense of history, as seen by those living at that time. It also lets you see some good examples of the standard tropes of reporters as well as some astronomers. They always say this new telescope (whatever and whenever it is) is going to allow us to discover the entire history of the universe, even though it never can, and never will.

Hat tip Mike Nelson.

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Merging galaxies

10:02 am

Merging galaxies
Click for original image.

Time for another cool image from the Hubble Space Telescope. The picture to the right, cropped, reduced, and sharpened to post here, was taken by Hubble to study “the overall physical characteristics of galaxies and their star formation.”

What the picture however reveals best is the ongoing merger of three galaxies.

Arp 300 consists of two interacting galaxies, UGC 05028 (the smaller face-on spiral galaxy) and UGC 05029 (the larger face-on spiral). Likely due to its gravitational dance with its larger partner, UGC 05028 has an asymmetric, irregular structure, which is not as visible from ground-based telescopes but is quite distinct in this new image from NASA’s Hubble Space Telescope. The bright knot visible to the southeast of the center of UGC 05028 may be the remnant of another small galaxy that is in the process of merging with that galaxy.

As always with Hubble galaxy images, there are a plethora of other background galaxies scattered about, including what appears to be another merger in the center right of two elliptical galaxies. In fact, except for one star in the lower right (with the four spikes), every other object in this photo is a galaxy of many shapes and distances.

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Webb confirms the unusual shape of early galaxies as seen by Hubble

9:52 am

Earth galaxies shapes, as seen by Webb in infrared
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The uncertainty of science: The infrared view of the Webb Space Telescope appears to have confirmed and even underlined the unusual shapes of many early galaxies as previously seen by the Hubble Space Telescope.

Researchers analyzing images from NASA’s James Webb Space Telescope have found that galaxies in the early universe are often flat and elongated, like surfboards and pool noodles – and are rarely round, like volleyballs or frisbees. “Roughly 50 to 80% of the galaxies we studied appear to be flattened in two dimensions,” explained lead author Viraj Pandya, a NASA Hubble Fellow at Columbia University in New York. “Galaxies that look like pool noodles or surfboards seem to be very common in the early universe, which is surprising, since they are uncommon nearby.”

The team focused on a vast field of near-infrared images delivered by Webb, known as the Cosmic Evolution Early Release Science (CEERS) Survey, plucking out galaxies that are estimated to exist when the universe was 600 million to 6 billion years old.

While most distant galaxies look like surfboards and pool noodles, others are shaped like frisbees and volleyballs. The “volleyballs,” or sphere-shaped galaxies, appear the most compact type on the cosmic “ocean” and were also the least frequently identified. The frisbees were found to be as large as the surfboard- and pool noodle-shaped galaxies along the “horizon,” but become more common closer to “shore” in the nearby universe.

The galaxies also appear generally far less massive than galaxies in the near universe, which fits with the Big Bang theory that says they had less time to grow.

The press release notes that the sample size is still very small, and further observations will be required to confirm whether these shapes are common in the early universe.

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One spiral galaxy eating another

9:51 am

One spiral galaxy eating another
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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 an on-going survey of known pecular-looking galaxies. This pair is believed to be 570 million light years away. From the caption:

Galaxies are composed of stars and their solar systems, dust and gas. In galactic collisions, therefore, these constituent components may experience enormous changes in the gravitational forces acting on them. In time, this completely changes the structure of the two (or more) colliding galaxies, and sometimes ultimately results in a single, merged galaxy. That may well be what results from the collision pictured in this image. Galaxies that result from mergers are thought to have a regular or elliptical structure, as the merging process disrupts more complex structures (such as those observed in spiral galaxies). It would be fascinating to know what Arp 122 will look like once this collision is complete . . . but that will not happen for a long, long time.

From our viewpoint, the spiral galaxy at the top appears warped by the gravitational pull of the face-on spiral at the bottom, as if it is being sucked into the bottom galaxy. In truth, both galaxies are pulling on each other. If we could circle around and see them in three dimensions we would almost certainly see distortions in the bottom spiral as well.

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Hubble detects changes in atmosphere of exoplanet

10:16 am

Using data from collected in 2016, 2018, and 2019 combined with computer simulations, scientists now believe they have detected changes in the atmosphere of the exoplanet WASP-121b, also nicknamed Tylos.

The Jupiter-sized planet orbits a star about 880 light years away.

WASP-121 b is so close to its parent star that the orbital period is only 1.27 days. This close proximity means that the planet is tidally locked so that the same hemisphere always faces the star, in the same way that our Moon always has the same side pointed at Earth. Daytime temperatures approach 3,450 degrees Fahrenheit (2,150 degrees Kelvin) on the star-facing side of the planet.

The team used four sets of Hubble archival observations of WASP-121 b. The complete data-set included observations of WASP-121 b transiting in front of its star (taken in June 2016); WASP-121 b passing behind its star, also known as a secondary eclipse (taken in November 2016); and the brightness of WASP-121 b as a function of its phase angle to the star (the varying amount of light received at Earth from an exoplanet as it orbits its parent star, similar to our Moon’s phase-cycle). These data were taken in March 2018 and February 2019, respectively.

A computer model was then used to fill in the gaps and provide a simulation of the hot temperatures of that exoplanet’s atmosphere over time. Two videos of that simulation are available at the link.

There of course is a lot of uncertainty in this result, though the fundamental discovery of changes is important. This data proves there is weather on such alien planets, even if that weather is so alien we really don’t understand it in the slightest based on the available data on hand.

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Galaxies galore, near and far

9:08 am

Galaxies galore, and near and far

Cool image for the day after Christmas! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope, and shows a cluster of galaxies that all seem near each other. However, as the caption notes,

[W]hilst NGC 1356 [the largest spiral] and LEDA 95415 [close by its left] appear to be so close that they must surely be interacting, the former is about 550 million light-years from Earth and the latter is roughly 840 million light-years away, so there is nearly a whopping 300 million light-year separation between them. That also means that LEDA 95415 is likely nowhere near as [small] as it appears to be.

On the other hand, whilst NGC 1356 and IC 1947 [farthest to the left] seem to be separated by a relative gulf in this image, IC 1947 is only about 500 million light-years from Earth. The angular distance apparent between them in this image only works out to less than four hundred thousand light-years, so they are actually much much closer neighbours in three-dimensional space than NGC 1356 and LEDA 95415!

The two galaxies farthest apart in this image are actually close enough together to interact significantly. Though this picture doesn’t have the resolution to see it, there is likely a stream of stars between the two.

Note also the numerous tiny other galaxies scatterered throughout the picture. In fact, except for three stars (the objects with the north-south-east-west spikes), every object is a galaxy holding stars too numerous to count.

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New Hubble image of Saturn

10:04 am

Saturn and its rings, as seen by Hubble

The annotated image above was taken by the Hubble Space Telescope on October 22, 2023, showing Saturn, its glorious rings, and several of its dozens of moons from a distance of about 850 million miles. For the unannotated version, go here. Of all the features, the spokes in the rings are the most intriguing.

Saturn’s spokes are transient features that rotate along with the rings. Their ghostly appearance only persists for two or three rotations around Saturn. During active periods, freshly-formed spokes continuously add to the pattern. In 1981, NASA’s Voyager 2 first photographed the ring spokes. Hubble continues observing Saturn annually as the spokes come and go. This cycle has been captured by Hubble’s Outer Planets Atmospheres Legacy (OPAL) program that began nearly a decade ago to annually monitor weather changes on all four gas-giant outer planets.

Hubble’s crisp images show that the frequency of spoke apparitions is seasonally driven, first appearing in OPAL data in 2021 but only on the morning (left) side of the rings. Long-term monitoring shows that both the number and contrast of the spokes vary with Saturn’s seasons. Saturn is tilted on its axis like Earth and has seasons lasting approximately seven years.

This year, these ephemeral structures appear on both sides of the planet simultaneously as they spin around the giant world. Although they look small compared with Saturn, their length and width can stretch longer than Earth’s diameter!

Though the origin of the spokes remains unsolved, the leading theory proposes they are caused by interactions between Saturn’s magnetic field and the seasonal changes in solar radiation.

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A bubbly dwarf galaxy

9:09 am

A bubbly dwarf galaxy
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was released today by the science team of the Hubble Space Telescope, and shows an irregular dwarf galaxy that is about seven million light years away.

Twelve camera filters were combined to produce this image, with light from the mid-ultraviolet through to the red end of the visible spectrum. The red patches are likely interstellar hydrogen molecules that are glowing because they have been excited by the light from hot, energetic stars. The other sparkles on show in this image are a mix of older stars. An array of distant, diverse galaxies appear in the background, captured by Hubble’s sharp view.

The data used in this image were taken by Hubble’s Wide Field Camera 3 and the Advanced Camera for Surveys from 2006 to 2021.

The picture was taken as part of a study of dwarf galaxies, their make-up, and how their mergers eventually create the larger galaxies like the Milky Way.

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A galaxy of violence

9:53 am

A galaxy of violence
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Time for another cool image! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope, and shows a well defined spiral galaxy face-on in optical wavelengths.

This whirling image features a bright spiral galaxy known as MCG-01-24-014, which is located about 275 million light-years from Earth. In addition to being a well-defined spiral galaxy, MCG-01-24-014 has an extremely energetic core, known as an active galactic nucleus (AGN), so it is referred to as an active galaxy. Even more specifically, it is categorised as a Type-2 Seyfert galaxy. Seyfert galaxies host one of the most common subclasses of AGN, alongside quasars. Whilst the precise categorisation of AGNs is nuanced, Seyfert galaxies tend to be relatively nearby ones where the host galaxy remains plainly detectable alongside its central AGN, while quasars are invariably very distant AGNs whose incredible luminosities outshine their host galaxies.

In contrast, the core of our own Milky Way galaxy is very quiet, which is likely a factor in why it was possible for life to form on Earth.

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Galaxies in a row

9:18 am

Galaxies in a row
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Cool image time from Hubble! 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 nearby “pecular” galaxies. What makes it unusual is the line of distant galaxies below the largest on the left.

The wonderful quality of this image also reveals several further galaxies, not associated with this system but fortuitously positioned in such a way that they appear to be forming a line that approaches the leftmost (in this image) component of Arp-Madore 2105-332, which is known individually as 2MASX J21080752-3314337. The rightmost galaxy, meanwhile, is known as 2MASX J21080362-3313196. These hefty names do not lend themselves to easy memorisation, but they do actually contain valuable information: they are coordinates in the right ascension and declination system used widely by astronomers to locate astronomical objects.

Both larger galaxies are thought to be about 200 million light years away, with the smaller ones far more distant. If you look at the full resolution image, you will see that there are at least six galaxies in that line, one that appears to be an elliptical galaxy with all the rest a variety of different types of spiral galaxies. The detail provided by Hubble is truly astonishing.

Though they are not linked to the larger galaxies, it is not clear if they are linked to each other.

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Hubble to resume science operations using three gyros

9:02 am

Engineers have apparently figured out the issues with one of the Hubble Space Telescope’s three gyroscopes, and plan to resume science operations today using all three gyros.

After analyzing the data, the team has determined science operations can resume under three-gyro control. Based on the performance observed during the tests, the team has decided to operate the gyros in a higher-precision mode during science observations. Hubble’s instruments and the observatory itself remain stable and in good health.

This is excellent news. If it had been determined that the funky gyro was no longer functional, the telescope would have shifted into what the engineers call “one-gyro mode.” By using only one of the two remaining gyros, Hubble’s life could be extended. However, while it would allow the telescope to point and continue observations, the images would no longer be as sharp.

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Hubble in safe mode due to gyroscope problem

8:58 am

One of the three working gyroscopes (three have already failed0 on the Hubble Space Telescope experienced repeated problems in mid-November, and has now put the telescope in safe mode while engineers trouble-shoot the problem.

Hubble first went into safe mode Nov. 19. Although the operations team successfully recovered the spacecraft to resume observations the following day, the unstable gyro caused the observatory to suspend science operations once again Nov. 21. Following a successful recovery, Hubble entered safe mode again Nov. 23.

The team is now running tests to characterize the issue and develop solutions. If necessary, the spacecraft can be re-configured to operate with only one gyro. 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 fluctuations. Hubble uses three gyros to maximize efficiency, but could continue to make science observations with only one gyro if required.

The long term plan when the telescope only has two working gyros, assuming no improvised maintenance mission is flown to Hubble to give it new gyroscopes, is to work with only one (treating the second as a back-up) in order to extend the telescope’s life as long as possible.

And though it is true that Hubble could continue to do science with only one gyro, images from that point will likely not be as sharp, and thus will end more than three decades of imagery that changed our perception of the universe.

The Chinese 2-meter Xuntian optical space telescope, now scheduled for launch in 2025, will likely then replace Hubble as the world’s top optical telescope. American astronomers better start learning Chinese, assuming China even allows them access. They will not have a right to complain, however, as it was their decision to not build a Hubble replacement, in their 2000, 2010, and 2020 decadal reports.

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Galaxies within galaxies within galaxies

9:54 am

Galaxies within galaxies
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Time another cool galaxy image! The picture to the right, cropped, reduced, sharpened, and annotated to post here, was taken by the Hubble Space Telescope as part of a survey project of galaxies where past supernovae had occurred. From the caption:

The location of this faded supernova was observed as part of a study of multiple hydrogen-rich supernovae, also known as type II supernovae, in order to better understand the environments in which certain types of supernovae take place.

Though the picture’s resolution was reduced to post here, I have also included insets at the full released resolution of three of background galaxies, one of which (on the uppermost right) appears to have a second smaller galaxy either associated with it or is another background galaxy even farther away. Such background galaxies are always seen Hubble images, which starkly tell us that the universe is far vaster than we can imaging, with more stars than we can conceive.

The galaxy featured here is interesting in its own right. Though it appears to be a spiral galaxy, its arms are very indistinct, suggesting that is sits between that of an elliptical galaxy (no arms, just a cloud of stars) and a spiral (with well-defined arms).

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Hubble snaps an ultra-violet view of Jupiter

9:59 am

Jupiter in ultra-violet

Cool image time! Using the Hubble Space Telescope, scientists have taken a false-color ultra-violet image of Jupiter. That picture is to the right, cropped, reduced and sharpened to post here.

This newly released image from the NASA Hubble Space Telescope shows the planet Jupiter in a color composite of ultraviolet wavelengths. Released in honor of Jupiter reaching opposition, which occurs when the planet and the Sun are in opposite sides of the sky, this view of the gas giant planet includes the iconic, massive storm called the “Great Red Spot.” Though the storm appears red to the human eye, in this ultraviolet image it appears darker because high altitude haze particles absorb light at these wavelengths. The reddish, wavy polar hazes are absorbing slightly less of this light due to differences in either particle size, composition, or altitude.

The data used to create this ultraviolet image is part of a Hubble proposal that looked at Jupiter’s stealthy superstorm system. The researchers plan to map deep water clouds using the Hubble data to define 3D cloud structures in Jupiter’s atmosphere.

By comparing this ultra-violet image with Hubble’s optical view as well as Webb’s infrared view, scientists can study Jupiter’s atmosphere much like meteologists study the Earth’s, using multi-wave satellite observations.

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A spiral galaxy giving birth to a lot of stars

10:01 am

A spiral galaxy giving birth to a lot of stars
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Time for another cool galaxy image! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope, and shows what some informally refer to as the “‘Spanish Dancer Galaxy’ because the “vivid and dramatic swirling lines of its spiral arms … evoke the shapes and colours of a dancer’s moving form. ”

Though this galaxy’s two main arms cause it to resemble a barred galaxy, it lacks a central bar, suggesting it is young. The numerous reddish and pink regions in the arms, all of which are thought to be star-forming regions, also suggest the galaxy is young, still giving birth to many stars.

It is located about 60 million light years away, and is part of what scientists label the Doradus galaxy group, which contains less than a hundred galaxies. In comparison, a galaxy cluster is much larger, containing hundreds to thousands of galaxies.

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An infrared view of the Crab Nebula by Webb

9:14 am

Webb's image of the Crabb compared to Hubble's
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Using the Webb Space Telescope astronomers have taken the first detailed infrared image of the Crab Nebula, the remnant from a supernova that occurred in 1054 AD.

The two pictures on the right compare Webb’s false color infrared view with a natural light Hubble image in optical wavelengths, taken in 2005. From the press release:

The supernova remnant is comprised of several different components, including doubly ionized sulfur (represented in red-orange), ionized iron (blue), dust (yellow-white and green), and synchrotron emission (white). In this image, colors were assigned to different filters from Webb’s NIRCam and MIRI: blue (F162M), light blue (F480M), cyan (F560W), green (F1130W), orange (F1800W), and red (F2100W).

In comparing the images, it appears the scientists chose colors for the Webb image to more or less match those of Hubble’s natural color picture. However, as the press release notes:

Additional aspects of the inner workings of the Crab Nebula become more prominent and are seen in greater detail in the infrared light captured by Webb. In particular, Webb highlights what is known as synchrotron radiation: emission produced from charged particles, like electrons, moving around magnetic field lines at relativistic speeds. The radiation appears here as milky smoke-like material throughout the majority of the Crab Nebula’s interior.

This feature is a product of the nebula’s pulsar, a rapidly rotating neutron star. The pulsar’s strong magnetic field accelerates particles to extremely high speeds and causes them to emit radiation as they wind around magnetic field lines. Though emitted across the electromagnetic spectrum, the synchrotron radiation is seen in unprecedented detail with Webb’s NIRCam instrument.

The release also notes this remarkable but somewhat unfortunate fact:

Scientists will have newer Hubble data to review within the next year or so from the telescope’s reimaging of the supernova remnant. This will mark Hubble’s first look at emission lines from the Crab Nebula in over 20 years, and will enable astronomers to more accurately compare Webb and Hubble’s findings.

In 2005 repeated Hubble images of the Crab revealed that its filaments and radiation were stormy, with constant activity. The scientists actually produced a movie of those changes. It was expected that new images would be taken at regular intervals to track that activity. Apparently it was not, either because no scientist was interested or the committee that assigns time on Hubble decided this wasn’t important enough reseach.

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A dance of three galaxies

10:40 am

Three galaxies merging
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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. Though it appears to show two galaxies interacting with each other, other spectroscopic data proves there are actually three large galaxies in the picture. From the caption:

The two clearly defined galaxies are NGC 7733 (smaller, lower right) and NGC 7734 (larger, upper left). The third galaxy is currently referred to as NGC 7733N, and can actually be spotted in this picture if you look carefully at the upper arm of NGC 7733, where there is a visually notable knot-like structure, glowing with a different colour to the arm and obscured by dark dust. This could easily pass as part of NGC 7733, but analysis of the velocities (speed, but also considering direction) involved in the galaxy shows that this knot has a considerable additional redshift, meaning that it is very likely its own entity and not part of NGC 7733.

All three galaxies are quite close to each other, which means they are in the long process of merging together into one larger galaxy.

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Astronomers detect nano-sized quartz crystals in atmosphere of exoplanet

9:33 am

Using both the Hubble and Webb space telescopes in space, astronomers have detected nano-sized quartz crystals in the atmosphere of a Jupiter-class exoplanet orbiting its star every 3.7 days.

Silicates (minerals rich in silicon and oxygen) make up the bulk of Earth and the Moon as well as other rocky objects in our solar system, and are extremely common across the galaxy. But the silicate grains previously detected in the atmospheres of exoplanets and brown dwarfs appear to be made of magnesium-rich silicates like olivine and pyroxene, not quartz alone – which is pure SiO2.

The result from this team, which also includes researchers from NASA’s Ames Research Center and NASA’s Goddard Space Flight Center, puts a new spin on our understanding of how exoplanet clouds form and evolve. “We fully expected to see magnesium silicates,” said co-author Hannah Wakeford, also from the University of Bristol. “But what we’re seeing instead are likely the building blocks of those, the tiny ‘seed’ particles needed to form the larger silicate grains we detect in cooler exoplanets and brown dwarfs.”

These tiny quartz crystals are condensing out in the clouds themselves, due to the high temperatures and pressures there. The exoplanet itself is unusual because though its mass is one half that of Jupiter, its volume is seven times larger. This gives it a very large and deep atmosphere, thus providing the environment for crystal formation.

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Astronomers detect baffling blue transient far outside any galaxy

11:32 am

Transient in intergalactic space
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Using a variety of telescopes, astronomers have discovered a baffling short-term object that brightens quickly in blue light and then fades.

What makes this discovery even more baffling is that though other such Luminous Fast Blue Optical Transients (LFBOT) have been discovered, all have been within galaxies, while this new discovery is in intergalactic space, as shown by the red bars in the picture to right, taken by the Hubble Space Telescope and cropped, reduced, and sharpened to post here. From the caption:

[An LFBOT] shines intensely in blue light and evolves rapidly, reaching peak brightness and fading again in a matter of days, unlike supernovae which take weeks or months to dim. Only a handful of previous LFBOTs have been discovered since 2018. The surprise is that this latest transient, seen in 2023, lies at a large offset from both the barred spiral galaxy at right and the dwarf galaxy to the upper left. Only Hubble could pinpoint its location. And, the results are leaving astronomers even more confounded because all previous LFBOTs have been found in star-forming regions in the spiral arms of galaxies. It’s not clear what astronomical event would trigger such a blast far outside of a galaxy.

The frequent discovery of such short term transients in the past decade is because there are now many telescopes dedicated to making daily surveys of the entire sky. In the past such quick events were always missed.

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A nearby active galaxy, viewed head on by Hubble

9:39 am

Active galaxy
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Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope and is the third of a seven-day celebration of galaxies by the Hubble science team. Previous images in the series can be found here. From the caption for this particular image:

At the center of NGC 6951 lies a supermassive black hole surrounded by a ring of stars, gas, and dust about 3,700 light-years across. This “circumnuclear ring” is between 1 and 1.5 billion years old and has been forming stars for most of that time. Scientists hypothesize that interstellar gas flows through the dense, starry bar of the galaxy to the circumnuclear ring, which supplies new material for star formation. Up to 40 percent of the mass in the ring comes from relatively new stars that are less than 100 million years old. Spiral lanes of dust, shown in dark orange, connect the center of the galaxy to its outer regions, contributing more material for future star formation.

This galaxy, located about 78 million light years away, has also seen six different supernovae in the past quarter century. Compare that with the Milky Way, which has not seen a supernova now in more than four hundred years.

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Hubble data shows expansion of supernova remnant

9:57 am

Cygnus loop filament

Astronomers have created a four-second long movie using Hubble images collected over twenty years that shows the expansion of one filament in the Cygnus Loop supernova remnant, the explosion of which is thought to have occurred 20,000 years ago.

The picture above is one frame of that movie. The filament is estimated to be two light years in length.

By analyzing the shock’s location, astronomers found that the shock hasn’t slowed down at all in the last 20 years, and is speeding into interstellar space at over half a million miles per hour – fast enough to travel from Earth to the Moon in less than half an hour. While this seems incredibly fast, it’s actually on the slow end for the speed of a supernova shock wave.

Two versions of the movie are at the link, with the longer providing excellent context.

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Two galaxies merging

11:32 am

Merging galaxies
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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 project to photograph the entire Arp catalog of 338 “peculiar galaxies,” put together by astronomer Halton Arp in 1966. From the caption:

The larger galaxy (in the left of this image) is an extremely energetic galaxy type known as a Seyfert galaxy, which house active galactic nuclei at their cores. Seyfert galaxies are notable because despite the immense brightness of the active core, radiation from the entire galaxy can be observed. This is evident in this image, where the spiraling whorls of the whole galaxy are readily visible. The smaller companion is connected to the larger by a tenuous-seeming ‘bridge’, composed of dust and gas. The colliding galactic duo lie about 465 million light-years from Earth.

Note that if you ignore the blue whorls of the left galaxy, the two bright cores of these merging galaxies are about the same size. As it is unclear how long this merger has been on-going, it is possible that the galaxy on the right, in circling the left galaxy, drew out those whorls and that tenuous bridge. Other scenarios are also possible, however, such as the galaxy on the left stripping and scattering the arms of the galaxy on the right.

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A galactic cloud

9:27 am

A galactic cloud
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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. It shows what scientists dub a lenticular galaxy, with features that put it somewhere between a spiral galaxy and an elliptical (which has no structure a appears instead a cloud of stars), sitting about 73 million light years away.

NGC 3156 has been studied in many ways … from its cohort of globular clusters, to its relatively recent star formation, to the stars that are being destroyed by the supermassive black hole at its centre.

Why this galaxy has no spiral arms is somehow related to its age and its central black hole, but the detailed theories that astronomers have to explain this are far from confirmed.

The image is interesting also because of its lack of foreground stars or background galaxies. Its location in the sky explains this, as Hubble was looking at right angle to the Milky Way’s galactic plane, essentially looking directly into the vast emptiness between the galaxies.

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A triangular spiral galaxy

9:25 am

A triangular spiral galaxy
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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 follow-up observations of a supernova that occurred in this galaxy in 2015. The galaxy, dubbed IC 1776, is about 150 million light years away.

Hubble investigated the aftermath of the supernova SN 2015ap during two different observing programmes, both designed to comb through the debris left by supernovae explosions in order to better understand these energetic events. A variety of telescopes automatically follow up the detection of supernovae to obtain early measurements of these events’ brightnesses and spectra. Complementing these measurements with later observations which reveal the lingering energy of supernovae can shed light on the systems which gave rise to these cosmic cataclysms in the first place.

As the caption notes, the spiral arms of this galaxy “are difficult to distinguish.” At first glance the galaxy instead appears triangular in shape, an impression that dissolves with a closer look.

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A ghostly bullseye galaxy

11:18 am

A ghostly bullseye
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A cool image to start the week! The picture to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope as part of a survey scientists are doing using Hubble, attempting to get high resolution images of every galaxy within about 30 million light years of the Milky Way. Prior to this census Hubble had covered about 75% of these galaxies. This particular galaxy is called a lenticular galaxy.

Lenticular galaxies like NGC 6684 (lenticular means lens-shaped) possess a large disc but lack the prominent spiral arms of galaxies like the Andromeda Galaxy. This leaves them somewhere between elliptical galaxies and spiral galaxies, and lends these galaxies a diffuse, ghostly experience. NGC 6684 also lacks the dark dust lanes that thread through other galaxies, adding to its spectral, insubstantial appearance.

The unknown is whether this is the state of a galaxy prior to becoming a spiral, or it is what it looks like as it transitions from a spiral to an elliptical. This particular galaxy is likely the latter, as it lacks the dust, but this does not have to be the rule.

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Spirals within spirals

8:58 am

Spirals within spirals
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Cool image time! The picture to the right, cropped, reduced, and annotated to post here, was taken by the Hubble Space Telescope as part of two different research projects that are studying galaxies where supernovae previously occurred. This particular galaxy is estimated to be about 192 million light years away, and is a classic example of a barred spiral.

Despite appearing as an island of tranquillity in this image, UGC 12295 played host to a catastrophically violent explosion — a supernova — that was first detected in 2015. This supernova prompted two different teams of astronomers to propose Hubble observations of UGC 12295 that would sift through the wreckage of this vast stellar explosion.

Supernovae are the explosive deaths of massive stars, and are responsible for forging many of the elements found here on Earth. The first team of astronomers used Hubble’s Wide Field Camera 3 (WFC3) to examine the detritus left behind by the supernova in order to better understand the evolution of matter in our Universe.

The second team of astronomers also used WFC3 to explore the aftermath of UGC 12295’s supernova, but their investigation focused on returning to the sites of some of the best-studied nearby supernovae. Hubble’s keen vision can reveal lingering traces of these energetic events, shedding light on the nature of the systems that host supernovae.

What struck me about this picture however were the many smaller spiral galaxies scattered nearby and behind UGC 12295, with one face-on spiral highlighted near the top. I can count at least three or four other background spiral galaxies, all reddish in color likely because their light has been shifted to the red due to their distance.

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A spiral galaxy as seen by Hubble

9:40 am

A spiral galaxy as seen by Hubble
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken as part of a research project to use the Hubble Space Telescope to photograph galaxies where supernovae had recently occurred. From the caption:

UGC 11860 lies around 184 million light-years away in the constellation Pegasus, and its untroubled appearance can be deceiving; this galaxy recently played host to an almost unimaginably energetic stellar explosion.

A supernova explosion — the catastrophically violent end of a massive star’s life — was detected in UGC 11860 in 2014 by a robotic telescope dedicated to scouring the skies for transient astronomical phenomena; astronomical objects which are only visible for a short period of time. Two different teams of astronomers used Hubble’s Wide Field Camera 3 to search through the aftermath and unpick the lingering remnants of this vast cosmic explosion.

This Hubble image once again illustrates the vastness of the universe. Note that every single dot surrounding UGC 11860 in this picture is another far more distant galaxy. As much as UGC 11860 is in our local intergalactic neighborhood, it is still so distant that this field of view is small enough that it contains no stars.

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A faint irregular cloud of stars

9:06 am

A faint irregular cloud of stars
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was released today by the science team of the Hubble Space Telescope. It shows an irregular galaxy thought to be about 44 million light years away.

Alongside its hazy shape, NGC 7292 is remarkably faint. As a result, astronomers classify NGC 7292 as a low surface brightness galaxy, barely distinguishable against the backdrop of the night sky. Such galaxies are typically dominated by gas and dark matter rather than stars.

Astronomers directed Hubble to inspect NGC 7292 during an observational campaign studying the aftermath of Type II supernovae. These colossal explosions happen when a massive star collapses and then violently rebounds in a catastrophic explosion that tears the star apart. Astronomers hope to learn more about the diversity of Type II supernovae they have observed by scrutinising the aftermath and remaining nearby stars of a large sample of historical Type II supernovae.

NGC 7292’s supernova was observed in 1964 and accordingly given the identifier SN 1964H. Studying the stellar neighbourhood of SN 1964H helps astronomers estimate the initial mass of the star that went supernova, and could uncover surviving stellar companions that once shared a system with the star that would become SN 1964H.

I searched but was unable to locate any 1964 images of this galaxy when the supernova was still visible, so I could not pinpoint its location in the picture. It has long since faded away.

Note that the reddish smudges scattered throughout the picture are likely galaxies so far distant that their light has shifted entirely into the reddish spectrum. This likely places them one to several billions of light years away, not millions.

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Hubble snaps picture of another jellyfish galaxy

10:05 am

Another jellyfish galaxy
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Astronomers today released another picture of a jellyfish galaxy taken by the Hubble Space Telescope, with that picture to the right, cropped, reduced, and sharpened to post here. From the caption:

The jellyfish galaxy JO206 trails across this image from the NASA/ESA Hubble Space Telescope, showcasing a colourful star-forming disc surrounded by a pale, luminous cloud of dust. A handful of bright stars with criss-cross diffraction spikes stand out against an inky black backdrop at the bottom of the image. JO206 lies over 700 million light-years from Earth in the constellation Aquarius.

This image is the sixth and final such photograph in this survey. You can view all of these images here. The study has found that star formation does not seem to be significantly different inside the galaxy versus the tentacles that stretch out beyond due to pressure from the intergalactic material. This suggests that the influence of this intergalactic material on the formation of stars is relatively minor.

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Jellyfish galaxy plowing its way through the intercluster medium

10:01 am

Jellyfish galaxy plowing through the intercluster medium
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The European Space Agency (ESA) today released another in a series of images taken by the Hubble Space Telescope during the past two years of what astronomers call jellyfish galaxies, so named because such galaxies have tendrils that extend out beyond the galaxy like the tendrils of jellyfish. This new picture is to the right, cropped, reduced, and sharpened to post here, and shows a galaxy about 900 million light years away.

[T]he space between galaxies in a cluster is … pervaded with a searingly hot plasma known as the intracluster medium. While this plasma is extremely tenuous, galaxies moving through it experience it almost like swimmers fighting against a current, and this interaction can strip galaxies of their star-forming gas. This interaction between the intracluster medium and the galaxies is called ram-pressure stripping, and is the process responsible for the trailing tendrils of this jellyfish galaxy.

The arrow in the image indicates the galaxy’s direction of travel through the intercluster medium, resulting in the outer parts of the leading arm to be pushed backward above the galaxy, while material at its rear trail behind. Note also the blue star-forming regions at the galaxy’s bow. The ram pressure is also apparently causing more star formation in this part of the galaxy compared to elsewhere.

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