Tag: astronomy

Scientists find oldest known reference to a solar eclipse dated approximately 6,000 years ago

9:36 am

In studying an ancient Hindu text called the Rig Veda that was compiled around 1,500 BC, scientists have found what they think is the oldest known reference to a solar eclipse, dated approximately 6,000 years ago.

You can read the peer-reviewed paper here [pdf]. From the paper’s conclusion:

We propose that the eclipse recorded in the Rig Veda refers to observations made of an eclipse around 4000 BC. By analyzing the description, we propose that the eclipse was the one that occurred in 4202 BC or else in 3811 BC. We propose that it was observed in Central Asia. To our knowledge, this is one of the oldest known references to a specific total solar eclipse mentioned in the historical literature.

The scientists came to this conclusion based on information contained and not contained in the Hindu text. The text noted the event occurred three days before the autmnal equinox, and that it occurred when that equinox occurred in the constellation Orion, when today the equinox occurs in the constellation Pisces. This reduced the number of possible eclipses to a small number during the time period around 4,000 BC. The text also lacked any mention of various Hindo myths explaining eclipses that appeared more recently, thus confirming this ancient date and telling the researchers that the nomadic people who compiled the Rig Veda were likely living in central Asia at that time.

The only two eclipses that fit the bill occurred on either October 22, 4202 BC or October 9, 3811 BC. This makes it the earliest known reference to an eclipse, far earlier than the possible eclipses that occurred in around 3340 BC and around 1300 BC.

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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
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of galaxies 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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Webb finds six exoplanets, all flying in interstellar space without a star

11:11 am

Astronomers using the Webb Space Telescope have discovered six different planets ranging in mass 5 to 10 times that of Jupiter, all unattached to any star or solar system.

The most intriguing of the starless objects is also the lightest, having an estimated mass of five Jupiters (about 1,600 Earths). The presence of a dusty disk means the object almost certainly formed like a star, as space dust generally spins around a central object in the early stages of star formation, said Langeveld, a postdoctoral researcher in Jayawardhana’s group.

All of these starless planets likely formed like this one, coalescing like a star does but unlike a star never having enough mass to ignite.

The astronomers are next going to attempt to detect the atmosphere’s of these rogue exoplanets, though it is not clear exactly how they will do this unless one of the exoplanets just happened to transit across a more distant star, something that simply does not happen very often.

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A real whirlpool in space

9:52 am

A real whirlpool in space
Click for original image.
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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The North Star has spots!

9:38 am

The spoted surface of Polaris
Click for original image.

Astronomers using an array of six ground-based telescopes have obtained best new data of Polaris, the North Star, including the first rough image of its surface, and discovered sunspots on its surface.

You can read the paper here [pdf]. The image to the right, taken from figure 4 of the paper, shows the surface as seen by the telescopes over two nights in April 2021. Polaris is what astronomers call a Cepheid variable star, which changes brightness on a very precise schedule as its diameter grows and shrinks. In the case of Polaris, that variation is four days long. The star’s brightness itself varies only slightly, and over the decades has even at times appeared to cease its variations.

As the true brightness of Cepheids is very predictable based on their pulse rate, these stars are one of the main tools astronomers use to determine distances to other galaxies. Knowing more about them thus has great importance to cosmological research.

The orbital motion showed that Polaris has a mass five times larger than that of the Sun. The images of Polaris showed that it has a diameter 46 times the size of the Sun.

The biggest surprise was the appearance of Polaris in close-up images. The CHARA observations provided the first glimpse of what the surface of a Cepheid variable looks like. “The CHARA images revealed large bright and dark spots on the surface of Polaris that changed over time,” said Gail Schaefer, director of the CHARA Array. The presence of spots and the rotation of the star might be linked to a 120-day variation in measured velocity.

The researchers plan to take regular images again of Polaris to better track the changes to its surface.

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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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Astronomers discover a nearby star moving so fast it could even escape the Milky Way

10:20 am

Astronomers, both professional and amateur, have discovered a nearby star only 400 light years away that is moving so fast, 1.3 million miles per hour (almost three times faster than the Sun), it might very well escape the Milky Way and fly into intergalactic space in the far future.

The star, named CWISE J124909+362116.0 (or “J1249+36” for short), was first spotted by some of the over 80,000 citizen science volunteers participating in the Backyard Worlds: Planet 9 project, who comb through enormous reams of data collected over the past 14 years by NASA’s Wide-field Infrared Survey Explorer (WISE) mission. This project capitalizes on the keen ability of humans, who are evolutionarily programmed to look for patterns and spot anomalies in a way that is unmatched by computer technology. Volunteers tag moving objects in data files and when enough volunteers tag the same object, astronomers investigate.

J1249+36 immediately stood out because it was moving at about .1 percent the speed of light.

The star itself is either a very low mass red dwarf, or possibly a brown dwarf that never quite had enough mass to ignite as a star.

You can read the research paper here [pdf]. The researchers posit two possible explanations for the star’s speed. Either it was once part of a binary and thrown out when its white dwarf companion exploded as a supernova, or was once located in a densely packed globular cluster, where the interaction with other stars or even black holes could have flung it away.

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A galaxy with a ring

9:34 am

A galaxy with a ring
Click for full image.

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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WISE/NEOWISE space telescope mission ends after fourteen years

9:11 pm

Comet NEOWISE, photographed by the Hubble Space Telescope
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Launched in 2009, the Wide-field Infrared Survey Explorer (WISE) was shut down today after almost fourteen years of successful observations, with its first years dedicated to creating an infrared survey of the sky. In 2013, after two years of hibernation, it was reactivated and renamed NEOWISE (for reasons that I have always found absurd), with the goal over the next thirteen years of mapping the sky for near Earth objects.

By repeatedly observing the sky from low Earth orbit, NEOWISE created all-sky maps featuring 1.45 million infrared measurements of more than 44,000 solar system objects. Of the 3,000-plus near-Earth objects it detected, 215 were first spotted by NEOWISE. The mission also discovered 25 new comets, including the famed comet C/2020 F3 NEOWISE that streaked across the night sky in the summer of 2020.

A Hubble image of that comet is to the right.

The mission was ended because the telescope’s orbit is now too low to provide good data. It is expected to re-enter the atmosphere and burn up before the end of the year.

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Gaia space telescope identifies more than 350 asteroids with candidate moons

9:24 am

Using the Gaia space telescope, astronomers have identified 352 asteroids that the data suggests have smaller satellite asteroids in orbit around them.

In its data release 3, Gaia precisely pinpointed the positions and motions of 150 000+ asteroids — so precisely that scientists could dig deeper and hunt for asteroids displaying the characteristic ‘wobble’ caused by the tug of an orbiting companion (the same mechanism as displayed here for a binary star). Gaia also gathered data on asteroid chemistry, compiling the largest ever collection of asteroid ‘reflectance spectra’ (light curves that reveal an object’s colour and composition).

These results need to be confirmed by direct observation, as this method does involve some assumptions and uncertainties. If these numbers are confirmed however it will give planetary scientists a better census on the percentage of asteroids with moons, which in turn can be used to create better models of the formation of the solar system as well as the evolution of asteroids over time. At the moment scientists predict about one out of every six asteroids will have a moon. This data suggests that number might be high.

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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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Inspector General: Roman Space Telescope is meeting the budget overruns and schedule delays NASA predicted

4:57 pm

According to the twisted language in a new NASA inspector general report [pdf] describing the present status of the Roman Space Telescope, the project is on schedule and on budget because NASA decided to predict ahead of time how much it would behind schedule and over budget at this moment. From its executive summary:

[A]s of March 2024, Roman was meeting its cost obligations and schedule to launch by May 2027. Roman was on track to launch despite encountering contractor performance issues and cost overruns related to hardware anomalies, under scoping of work, and inadequate oversight of subcontractors. Roman remains on schedule because Science Mission Directorate officials conducted a replan in May 2021 to mitigate the expected cost and schedule growth caused by COVID-19, increasing the life-cycle cost estimate from $3.9 billion to $4.3 billion. This replan also included delaying the launch readiness date from October 2026 to May 2027. As of March 2024, Roman was tracking its project reserves and potential delays with L3Harris as its top risks. Roman has been using its project reserves to mitigate cost growth related to L3Harris’s performance challenges. Despite these contract value increases, Roman is still within its life-cycle cost estimate because the project’s reserves cover these extra costs.

The insulting nature of this inspector general report is astonishing. The administrative state really does think the American public is too stupid to notice this. I wonder if they are right.

The report further notes issues with the telescope’s two subcontractors, BAE Systems and L3Harris, as well as warning of insufficient ground-based antenna capacity for downloading the data that Roman will produce.

[A]s of April 2024, the NSN [Near Space Network] did not have adequate capacity to support Roman’s mission requirements without planned upgrades to the White Sands antenna and lacked the funding to implement the necessary upgrades by the mission’s launch readiness date.

In other words, more money will be needed to build more ground antennas, something that NASA conveniently forgot to mention when it first proposed Roman to Congress. How interesting, but completely par for the course.

Hat tip stringer Jay.

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Do Kepler’s sunspot drawings tell us the length of the solar cycle in the 17th century?

9:19 am

Kepler's first sunspot drawing
Click for original image.

The uncertainty of science: Scientists have done a new analysis of Johannes Kepler’s three drawings of sunspots on the Sun in 1607, and have concluded that the solar cycle at that time — just before the start of the Maunder grand minimum of no sunspots for decades — was about the same length, 11 years, that has been measured since the 1700s onward.

You can read the peer-reviewed paper here. The drawing to the right is figure 1 in that paper, and shows Kepler’s first drawing of the Sun’s surface showing sunspots. From the paper’s conclusion:

In combination with sunspot drawings in the 1610s–1620s, it is reasonable to suppose that the duration of the Solar Cycle −13 was between 11 and 14 yr. This does not support Miyahara et al.’s claim of anomalously long/short durations for Solar Cycle −13 (16 yr) and Solar Cycle −14 (5 yr) but supports Usoskin et al.’s reconstruction of regular durations of Solar Cycle −13 (11 yr) and Solar Cycle −14 (14 yr).

In other words, the solar cycle prior to the sixty-plus yearlong Maunder Minimum, when few to none sunpots occurred, was about eleven years long, like now, and not five years or sixteen years long, as some scientists have theorized. Knowing the length and nature of the cycle before the Maunder grand minimum would help scientists predict when the next minimum might occur. It would also help them better document the Sun’s long term behavior.

There is however great uncertainty in this result, since there really is so little data about sunspots prior to the Maunder Minimum. Before Galileo’s first use of the telescope in astronomy in 1609, such observations like Kepler’s were rare and very difficult. The conclusions here are intriguing, but hardly convincing.

In fact, it is really impossible to get a defiinitive answer from this data. We really won’t know how the Sun behaves just prior to a grand minimum until it happens again and scientists can use modern technology to observe it.

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Webb: Carbon monoxide detected on surface of Uranus’s moon Ariel suggests an underground ocean

12:04 pm

The best image of Ariel, as seen by Voyager-2, January 24, 1986
Voyager-2’s best image of Ariel during the
January 24, 1986 fly-by. Click for original.

By doing infrared spectroscopy using the Webb Space Telescope, scientists have detected carbon monoxide (CO) and confirmed extensive carbon dioxide (CO2) deposits on the surface of Uranus’s moon Ariel, with the carbon monoxide suggesting the moon has an underground ocean.

Using NASA’s James Webb Space Telescope to collect chemical spectra of the moon and then comparing them with spectra of simulated chemical mixtures in the lab, a research team led by Richard Cartwright from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, found that Ariel has some of the most carbon dioxide-rich deposits in the solar system, adding up to an estimated 10 millimeters (0.4 inches) or more thickness on the moon’s trailing hemisphere. Among those deposits was another puzzling finding: the first clear signals of carbon monoxide.

“It just shouldn’t be there. You’ve got to get down to 30 kelvins [minus 405 degrees Fahrenheit] before carbon monoxide’s stable,” Cartwright said. Ariel’s surface temperature, meanwhile, averages around 65 F warmer. “The carbon monoxide would have to be actively replenished, no question.”

You can read the peer-reviewed paper here [pdf]. Though there are a number of ways in which the carbon monoxide can be replenished, the scientists think it is coming from an underground ocean. From the paper’s abstract:

The evidence for thick CO 2 ice deposits and the possible presence of carbonates on both hemispheres suggests that some carbon oxides could be sourced from Ariel’s interior, with their surface distributions modified by charged particle bombardment, sublimation, and seasonal migration of CO and CO 2 from high to low latitudes.

This theory however has not been confirmed, and the scientists admit it will take a probe making close observations of Ariel to find out for sure.

Hat tip to stringer Jay for this story.

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Webb takes infrared image of exoplanet

10:02 am

A Jupiter-sized exoplanet imaged by Webb
Click for original image.

Cool image time! Using the Webb Space Telescope, scientists have taken an infrared false color image of a multi-Jupiter-sized exoplanet located only twelve light years away and orbiting the K-type star Epsilon Indi A.

That picture, cropped, reduced, and sharpened to post here, is to the right. The light of the star, indicated by the star symbol, has been blocked by Webb’s coronagraph, the size of which is shown by the dashed circle. The exoplanet is the orange blob to the left.

[This exoplanet] is one of the coldest exoplanets to be directly detected, with an estimated temperature of 35 degrees Fahrenheit (2 degrees Celsius) — colder than any other imaged planet beyond our solar system, and colder than all but one free-floating brown dwarf. The planet is only around 180 degrees Fahrenheit (100 degrees Celsius) warmer than gas giants in our solar system. This provides a rare opportunity for astronomers to study the atmospheric composition of true solar system analogs.

The data also revealed that the exoplanet is twice as massive as expected and has a slightly different orbit than expected based on previous less precise data.

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New collection of X-ray false-color Chandra images

9:30 am

Chandra image of galaxy
Click for original image.

Cool image time! As part of a PR campaign by NASA to convince Congress to give it more money to keep the Chandra X-ray Observatory funded, the agency this week released twenty-five new images, supposedly to celebrate the space telescope’s 25th anniversary since launch.

It must be emphasized that these photos are not solely produced by Chandra. They combine its X-ray data wth optical data from Hubble and infrared data from a number of other telescopes.

The picture to the right is of the galaxy NGC 6872 that is interacting with its nearby smaller neighbor. From the caption:

NGC 6872 is 522,000 light-years across, making it more than five times the size of the Milky Way galaxy; in 2013, astronomers from the United States, Chile, and Brazil found it to be the largest-known spiral galaxy, based on archival data from NASA’s Galaxy Evolution Explorer. This record was surpassed by NGC 262, a galaxy that measures 1.3 million light-years in diameter.

Chandra will get its funding to continue operations. NASA is simply playing its old game of bluff with Congress to force it to give the agency a boost in funding. Like a toddler throwing a tantrum, it cancels a successful project, citing funding shortages (even though those shortages are almost always because of mismanagement elsewhere in the agency), and Congress eventually gives in like a weak parent, raising NASA’s budget.

The big image release this week is part of that game. Nonetheless, the images are spectacular, and loaded with new information not otherwise available without Chandra’s X-ray capabilities. If Congress had any spine, it would force NASA to fully fund such successful projects and simply delete the failed ones (such as SLS and Mars Sample Return). It has no spine, however, and thus we have a national debt in the trillions that is bankrupting us.

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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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Astronomers discover an exoplanet with the most eccentric orbit so far found

9:41 am

Using the TESS space telescope, astronomers have discovered a gas giant exoplanet with the most eccentric orbit so far found, circling a star about 1,100 light years away.

On Jan. 12, 2020, TESS picked up a possible transit of the star TIC 241249530. Gupta and his colleagues at Penn State determined that the transit was consistent with a Jupiter-sized planet crossing in front of the star. They then acquired measurements from other observatories of the star’s radial velocity, which estimates a star’s wobble, or the degree to which it moves back and forth, in response to other nearby objects that might gravitationally tug on the star. Those measurements confirmed that a Jupiter-sized planet was orbiting the star and that its orbit was highly eccentric, bringing the planet extremely close to the star before flinging it far out.

Prior to this detection, astronomers had known of only one other planet, HD 80606 b, that was thought to be an early hot Jupiter. That planet, discovered in 2001, held the record for having the highest eccentricity, until now.

The exoplanet’s orbit is presently 167 days long, at its closest stellar approach dipping 10 times closer to its star than Mercury is from the Sun, and at its farthest point zipping just beyond Earth’s distance.

Computer simulations suggest that in a billion years this orbit will decay into a more circular orbit close to the star, turning this gas giant into a hot Jupiter roasted by its star continually.

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Europe’s Gaia space telescope in trouble

9:34 am

Launched in 2013 and now functioning more than six years after the completion of its primary mission to measure precisely the distances to over a billion stars, the European Space Agency’s Gaia space telescope has experienced several major technical issues this spring related to a micrometeorite hit and a failure of the electronics of one of its CCDs.

The micrometeorite hit occurred in April.

The impact created a little gap that allowed stray sunlight – around one billionth of the intensity of direct sunlight felt on Earth – to occasionally disrupt Gaia’s very sensitive sensors. Gaia’s engineers were in the middle of dealing with this issue when they were faced with another problem.

The spacecraft’s ‘billion-pixel camera’ relies on a series of 106 charge coupled devices (CCDs) – sensors that convert light into electrical signals. In May, the electronics controlling one of these CCDs failed – Gaia’s first CCD issue in more than 10 years in space. Each sensor has a different role, and the affected sensor was vital for Gaia’s ability to confirm the detection of stars. Without this sensor to validate its observations, Gaia began to register thousands of false detections.

The cause of the electronics failure remains unsolved, though it is believed related to the major solar storm that swept by at about the same time.

As a result of these issues, the telescope’s data stream will be significantly reduced. How long it will remain in operation remains unclear. At some point the cost will outweigh the amount of data obtained.

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A blob in space

9:47 am

A blob in space
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope 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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Webb infrared spectroscopy detects differences between morning and evening on tidally-locked exoplanet

9:36 am

Webb spectroscopic data
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Astronomers using Webb Space Telescope’s infrared spectroscopy have now detected distinct differences in the morning and evening atmosphere of a tidally-locked gas giant exoplanet.

The graph, cropped, reduced, sharpened, annotated to post here, shows the differences. From the caption:

Researchers using NASA’s James Webb Space Telescope have finally confirmed what models have previously predicted: An exoplanet has differences between its eternal morning and eternal evening atmosphere. WASP-39 b, a giant planet with a diameter 1.3 times greater than Jupiter, but similar mass to Saturn that orbits a star about 700 light-years away from Earth, is tidally locked to its parent star. This means it has a constant dayside and a constant nightside—one side of the planet is always exposed to its star, while the other is always shrouded in darkness.

Using Webb’s NIRSpec (Near-Infrared Spectrograph), astronomers confirmed a temperature difference between the eternal morning and eternal evening on WASP-39 b, with the evening appearing hotter by roughly 300 Fahrenheit degrees (about 200 Celsius degrees). They also found evidence for different cloud cover, with the forever morning portion of the planet being likely cloudier than the evening.

The actual temperatures of each terminator are quite hot, approximately 1,150 and 1450 degrees Fahrenheit respectively. Computer modeling suggests “the prevailing winds are likely moving from the night side across the morning terminator, around the dayside, across the evening terminator and then around the nightside,” with wind speeds thousands of miles per hour.

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Radar detects tiny moon of asteroid

9:06 am

Binary asteroid
Click for original image.

Using the Goldstone radar dish, part of NASA’s Deep Space Network normally used to communicate with planetary missions, scientists have taken radar imageray of an asteroid that flew past the Earth at a distance of about 4.1 million miles on June 27, 2024, and discovered that it has its own tiny moon.

The series of radar images are above, reduced and cropped to post here.

Passing Earth on June 27, 2024, the asteroid was discovered in 2011 by the NASA-funded Catalina Sky Survey, in Tucson, Arizona. This marked the first time it came close enough to Earth to be imaged by radar. While the nearly mile-wide object is classified as being potentially hazardous, calculations of its future orbits show that it won’t pose a threat to our planet for the foreseeable future.

In addition to determining the asteroid is roughly spherical, scientists at NASA’s Jet Propulsion Laboratory discovered that it’s a binary system: A smaller asteroid, or moonlet, orbits it from a distance of about 1.9 miles.

It is intriguing that as their ability to make high resolution images of asteroids improves, scientists are discovering that such binary asteroid systems appear to be less and less rare, and might even be quite normal. If so, these facts will reshape all theories on the initial formation processes of the solar system.

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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
Click for original image.

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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Webb: An exoplanet in the habitable zone with a possible nitrogen/CO2 atmosphere and water ocean

8:51 am

Using the Webb Space Telescope, astronomers have obtained new transiting spectroscopy of a “mini-Neptune-sized” exoplanet that circles in the habitable zone a red dwarf star about 48 light years away and have concluded that it appears to have a nitrogen/carbon dioxide atmosphere and even a water ocean.

While it is still only a tentative result, the presence of a nitrogen-rich atmosphere on LHS 1140 b would suggest the planet has retained a substantial atmosphere, creating conditions that might support liquid water. This discovery favors the water-world/snowball scenario as the most plausible.

Current models indicate that if LHS 1140 b has an Earth-like atmosphere, it would be a snowball planet with a vast “bull’s-eye” ocean measuring about 4,000 kilometers in diameter, equivalent to half the surface area of the Atlantic Ocean. The surface temperature at the centre of this alien ocean could even be a comfortable 20 degrees Celsius [68 degrees Fahrenheit]. [emphasis mine]

You can read the preprint of the paper here [pdf].

The highlighted phrase must be noted. These results contain a lot of uncertainties and assumptions. However, the data is tantalizing, to say the least, and justify more observations using Webb. The scientists argue in their paper that because there are only about eight transits of the exoplanet per year — requiring several years of observations to pin down this data more precisely — and because Webb has a limited life expectancy as an infrared observatory, this star should get observational priority.

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Webb: Hot Jupiter exoplanet has atmosphere with the smell of rotten eggs

9:20 am

Using spectroscopy from the infrared Webb Space Telescope, astronomers have measured some of the molecules in exoplanet HD 189733 b, one of the first hot Jupiter exoplanets ever discovered, and found it has an atmosphere rich in hydrogen sulfide, which emits a smell like rotten eggs.

In addition to detecting hydrogen sulfide, the team analyzed the planet’s oxygen and carbon content, pinpointing water, carbon dioxide and carbon monoxide as major components of the planetary atmosphere. Measuring these heavy elements allows astronomers to compare the composition of exoplanets to that of gas giants in our solar system like Jupiter and Uranus.

The exoplanet, about 64 light years away, has an orbit lasting only about two Earth days, with atmospheric temperatures has hot as 1,700 degrees Fahrenheit.

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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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Webb takes false-color infrared image of bi-polar protostar nebula

10:02 am

Hourglass nebula as seen in infrared by Webb
Click for original image.

Scientists using the Webb Space Telescope have now produced a new false-color infrared image of the bi-polar hour-glass-shaped protostar nebula dubbed L1527.

That image is to the left, created from data from Webb’s MIRI (Mid-Infrared Instrument) and cropped, reduced, and sharpened to post here. While it is not quite a pretty as a prevous Webb infrared image taken in 2022 by its NIRCam (Near-Infrared Camera), it provides new information about the make-up of materials within this nebula. From the caption:

The areas colored here in blue, which encompass most of the hourglass, show mostly carbonaceous molecules known as polycyclic aromatic hydrocarbons. The protostar itself and the dense blanket of dust and a mixture of gases that surround it are represented in red. (The sparkler-like red extensions are an artifact of the telescopes’s optics). In between, MIRI reveals a white region directly above and below the protostar, which doesn’t show as strongly in the NIRCam view. This region is a mixture of hydrocarbons, ionized neon, and thick dust, which shows that the protostar propels this matter quite far away from it as it messily consumes material from its disk.

Previous to Webb, this object had mostly been studied in 2012 using radio and submillimeter wavelengths (see the papers here and here), but those papers determined this is possibly the youngest known protostar, less than 100,000 years old.

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Astronomers see a quiet galaxy become active for the first time

9:46 am

Using a number of space- and ground-based telescopes, astronomers have for the first time seen in real time what had previously been a very inactive and quiet galaxy become active and energetic, suggesting a major event at the galaxy’s center had taken place to change its behavior.

From the abstract of the paper [pdf]:

We conclude that the variations observed in SDSS1335+0728 could be either explained by a ∼ 10 6 M ⊙ AGN [a one million solar mass black hole] that is just turning on or by an exotic tidal disruption event (TDE). If the former is true, SDSS1335+0728 is one of the strongest cases of an AGN observed in the process of activating. If the latter were found to be the case, it would correspond to the longest and faintest TDE ever observed (or another class of still unknown nuclear transient). Future observations of SDSS1335+0728 are crucial to further understand its behaviour.

As noted in the press release:

Some phenomena, like supernova explosions or tidal disruption events — when a star gets too close to a black hole and is torn apart — can make galaxies suddenly light up. But these brightness variations typically last only a few dozen or, at most, a few hundreds of days. SDSS1335+0728 is still growing brighter today, more than four years after it was first seen to ‘switch on’. Moreover, the variations detected in the galaxy, which is located 300 million light-years away in the constellation Virgo, are unlike any seen before.

If the central black hole is switching from being quiet to active, this galaxy is providing astronomers critical information for understanding such changes. This is particularly important to us here in the Milky Way, which has a very inactive central supermassive black hole weighing about 4 million solar masses. It would be very useful to understand what would cause it to become active, especially because such an event might even have an impact — possibly negative — throughout our entire galaxy.

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Scientists release first image from Hubble in one-gyro mode

9:29 am

First Hubble image in one-gyro mode
Click for original image.

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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