Tag: astronomy

More results from DART impact of Dimorphos

9:44 am

Didymos and Dimorphos as seen from Earth
Click for movie.

At a science conference this week scientists provided an update on the changes that occurred to the asteroid Dimorphos after it was impacted by the DART spacecraft in September, shortening its orbit around the larger asteroid Didymos by 33 minutes.

The image to the right is a screen capture from a short movie made from 30 images taken by the Magdalena Ridge Observatory in New Mexico, and part of a new image release of the asteroid pair.

It shows the motion of the Didymos system across the sky over the course of roughly 80 minutes, and features a long, linear tail stretching to the right from the asteroid system to the edge of the frame. The animation is roughly 32,000 kilometers across the field of view at the distance of Didymos.

According to the scientists, the impact displaced more than two million pounds of material from Dimorphos.

Observations before and after impact, reveal that Dimorphos and its larger parent asteroid, Didymos, have similar makeup and are composed of the same material – material that has been linked to ordinary chondrites, similar to the most common type of meteorite to impact the Earth. These measurements also took advantage of the ejecta from Dimorphos, which dominated the reflected light from the system in the days after impact. Even now, telescope images of the Didymos system show how solar radiation pressure has stretched the ejecta stream into a comet-like tail tens of thousands of miles in length.

Putting those pieces together, and assuming that Didymos and Dimorphos have the same densities, the team calculates that the momentum transferred when DART hit Dimorphos was roughly 3.6 times greater than if the asteroid had simply absorbed the spacecraft and produced no ejecta at all – indicating the ejecta contributed to moving the asteroid more than the spacecraft did.

This information is teaching us a great deal about these two particular asteroids, which could be used if for some reason their totally safe orbit got changed and they were going to impact Earth. However, NASA’s repeated effort to make believe this info would be useful for deflecting other asteroids is somewhat absurd. It is helpful, but each asteroid is unique. The data from DART is mostly helping astronomers get a better understanding of the geology of these specific asteroids, which will widen their understanding of asteroids in general. Planetary defense is really a very minor aspect of this work.

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NASA approves $1.2 billion asteroid-hunting space telescope

8:51 am

NASA has given the go-ahead to build NEO-Surveyor for $1.2 billion, more than twice the cost of its original proposal, to launch by 2028 and then look for potentially dangerous asteroids.

Notably, NEO Surveyor was earlier estimated to cost between $500 million and $600 million, or around half of the new commitment. The NASA statement said that the cost and schedule commitments outlined align the mission with “program management best practices that account for potential technical risks and budgetary uncertainty beyond the development project’s control.” Earlier this year, the project’s launch was delayed two years, from 2026, due to agency budget concerns.

The mission is designed to discover 90% of potentially Earth-threatening asteroids and comets 460 feet (140 meters) or larger that come within 30 million miles (48 million kilometers) of Earth’s orbit. The spacecraft will carry out the survey while from Earth-sun Lagrange Point 1, a gravitationally stable spot in space about 930,000 miles (1.5 million kilometers) inside the Earth’s orbit around the sun.

A prediction: It will cost more, and not launch on time. NASA’s decision to double the budget and delay the launch two years suggests it did not trust the JPL cost and time estimates. Based on most NASA-centered projects, however, it is likely the new numbers will still be insufficient.

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A wall of smoke, as seen by Hubble

9:57 am

A wall of smoke, as seen by Hubble
Click for full image.

Using the Hubble Space Telescope, astronomers have produced a magnificent image of an interstellar cloud, cropped and reduced to post here. From the caption:

A portion of the open cluster NGC 6530 appears as a roiling wall of smoke studded with stars in this image from the NASA/ESA Hubble Space Telescope. NGC 6530 is a collection of several thousand stars lying around 4350 light-years from Earth in the constellation Sagittarius. The cluster is set within the larger Lagoon Nebula, a gigantic interstellar cloud of gas and dust. It is the nebula that gives this image its distinctly smokey appearance; clouds of interstellar gas and dust stretch from one side of this image to the other.

Astronomers investigated NGC 6530 using Hubble’s Advanced Camera for Surveys and Wide Field Planetary Camera 2. They scoured the region in the hope of finding new examples of proplyds, a particular class of illuminated protoplanetary discs surrounding newborn stars. The vast majority of proplyds have been found in only one region, the nearby Orion Nebula. This makes understanding their origin and lifetimes in other astronomical environments challenging.

The first proplyds were seen in the very first images taken by Hubble after it was fixed and could finally take sharp pictures. That so few have been seen since is thus somewhat surprising.

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Astronomers confirm Webb galaxies from the early universe

9:40 am

Astronomers using Webb have now confirmed with spectroscopy the age of at least four galaxies from the very very early universe, existing only a short time after the theorized Big Bang.

Four of the galaxies studied are particularly special, as they were revealed to be at an unprecedentedly early epoch. The results provided spectroscopic confirmation that these four galaxies lie at redshifts above 10, including two at redshift 13. This corresponds to a time when the universe was approximately 330 million years old, setting a new frontier in the search for far-flung galaxies. These galaxies are extremely faint because of their great distance from us.

The scientists had aimed Webb at Hubble’s Ultra Deep Field, doing a long infrared exposure lasting 28 hours over three days in order to gather the faintest infrared radiation (that Hubble could not see) and thus the most distant galaxies. The spectrum of individuals stars was then measured, which indicating their redshift and their estimated age.

The astronomers will next aim Webb at the more famous Hubble Deep Field, the first such long exposure that optical telescope took back in the late 1990s.

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SOFIA to retire to Arizona museum

9:28 am

NASA yesterday announced that its airborne 747 SOFIA telescope will be retired to the Pima Air & Space Museum in Tucson, Arizona, making its final flight there December 13, 2022.

Pima, one of the world’s largest aerospace museums, is developing plans for when and how the SOFIA aircraft will eventually be on display to the public. Along with six hangars, 80 acres of outdoor display grounds, and more than 425 aircraft from around the world, Pima also has its own restoration facility where incoming aircraft like SOFIA are prepared for museum immortalization after their arrival.

While the idea of SOFIA, putting a astronomical telescope on an airplane to get it above most of the atmosphere, has some merit, this particular NASA project was always too costly and simply produced too little science to justify its expense.

In many ways, this museum display will provide one of the best ways to see a 747 itself, now also retired.

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Webb’s infrared view of the Southern Ring Nebula

4:57 pm

Two views of Southern Ring Nebula by Webb
Click for original image.

The two images to the left were produced by the Webb Space Telescope, showing in false colors the Southern Ring Nebula as seen by two of Webb’s infrared cameras.

The two images shown here each combine near-infrared and mid-infrared data to isolate different components of the nebula. The image at [top] highlights the very hot gas that surrounds the central stars. The image at [bottom] traces the star’s scattered molecular outflows that have reached farther into the cosmos.

Based on the data, astronomers posit that up the system could have as many as five stars orbiting each other, with three as yet unseen, or the inner ones might no longer exist, having been absorbed by the bigger stars.

It’s possible more than one star interacted with the dimmer of the two central stars, which appears red in this image, before it created this jaw-dropping planetary nebula. The first star that “danced” with the party’s host created a light show, sending out jets of material in opposite directions. Before retiring, it gave the dim star a cloak of dust. Now much smaller, the same dancer might have merged with the dying star – or is now hidden in its glare.

A third partygoer may have gotten close to the central star multiple times. That star stirred up the jets ejected by the first companion, which helped create the wavy shapes we see today at the edges of the gas and dust. Not to be left out, a fourth star with an orbit projected to be much wider, also contributed to the celebration. It circled the scene, further stirring up the gas and dust, and generating the enormous system of rings seen outside the nebula. The fifth star is the best known – it’s the bright white-blue star visible in the images that continues to orbit predictably and calmly.

Much of this remains mere theory, based on the available data. Nonetheless, the data from many such planetary nebula continues to suggest their strange and wonderful shapes are created by multiple stars, acting as a mix-master to churn up the nebula’s dust.

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New gamma ray burst violates the explanations of scientists

9:04 am

The uncertainty of science: A newly discovered long gamma ray burst (GRB) that appears to have been formed by the merger of two neutron stars has contradicted the long held views of scientists as to the origin of this particular type of GRB.

Prior to the discovery of this burst, astronomers mostly thought that there were just two ways to produce a GRB. The collapse of a massive star just before it explodes in a supernova could make a long gamma-ray burst, lasting more than two seconds. Or a pair of dense stellar corpses called neutron stars could collide, merge and form a new black hole, releasing a short gamma-ray burst of two seconds or less.

But there had been some outliers. A surprisingly short GRB in 2020 seemed to come from a massive star’s implosion (SN: 8/2/21). And some long-duration GRBs dating back to 2006 lacked a supernova after the fact, raising questions about their origins. “We always knew there was an overlap,” says astrophysicist Chryssa Kouveliotou of George Washington University in Washington, D.C., who wrote the 1993 paper that introduced the two GRB categories, but was not involved in the new work. “There were some outliers which we did not know how to interpret.”

There’s no such mystery about GRB 211211A: The burst lasted more than 50 seconds and was clearly accompanied by a kilonova, the characteristic glow of new elements being forged after a neutron star smashup.

Kouveliotou’s claim is not how I remember things back in 1990s. Then, the astronomers seemed certain that the two GRB classes were entirely separate, with no overlap, despite the large number of uncertainties.

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Webb and Keck telescopes track clouds on Titan

11:08 am

Clouds on Titan
Click for original image.

Astronomers have used the Webb Space Telescope and the Keck Observatory in Hawaii to take infrared images days apart of the evolving clouds on the Saturn moon Titan.

The false-color infrared images to the right are those observations. From the press release:

As part of their investigation of Titan’s atmosphere and climate, Nixon’s team used JWST’s Near-Infrared Camera (NIRCam) to observe the moon during the first week of November. After seeing the clouds near Kraken Mare, the largest known liquid sea of methane on the surface of Titan, they immediately contacted the Keck Titan Observing Team to request follow-up observations.

“We were concerned that the clouds would be gone when we looked at Titan a day later with Keck, but to our delight there were clouds at the same positions on subsequent observing nights, looking like they had changed in shape,” said Imke de Pater, emeritus professor of astronomy at the University of California, Berkeley, who leads the Keck Titan Observing Team.

Using Keck Observatory’s second generation Near-Infrared Camera (NIRC2) in combination with the Keck II Telescope’s adaptive optics system, de Pater and her team observed one of Titan’s clouds rotating into and another cloud either dissipating or moving out of Earth’s field of view due to Titan’s rotation.

These images only increase my mourning for a Saturn orbiter. Since the end of Cassini’s mission in 2017, we have essentially been blind to the ringed planet and its many moons. These images, while producing excellent data, also illustrate well what we have lost.

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China completes construction of world’s largest solar radio telescope array

9:36 am

China has now completed the construction of world’s largest solar radio telescope array, dubbed the Daocheng Solar Radio Telescope (DSRT), made up of 313 separate radio dishes laid out in a giant two-mile wide circle.

DSRT is focused on observing solar flares and coronal mass ejections (CMEs) which can interfere with or overload electronics and wreak havoc on and above Earth. CMEs are triggered by realignments in the star’s magnetic field that occur in sunspots, and when directed at Earth, can threaten power grids, telecommunications, orbiting satellites and even put the safety of astronauts aboard the International Space Station and China’s newly-completed Tiangong space station at risk.

Assuming China shares the data from this telescope with the rest of the world, it will function as a back-up to several very old NOAA satellites in orbit that NOAA has failed to replace. If China doesn’t share the data, however, the western world will become very vulnerable should its own satellites finally fail.

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A ghost goddess in space

1:29 pm

Ghost goddess in space
Click for original image.

Cool image time! The image to the right, cropped, rotated, reduced, and enhanced to post here, is without doubt one of my favorite objects that the Hubble Space Telescope has photographed over the decades. This new image combines imagery obtained by earlier Hubble cameras and the newer cameras installed in 2009.

The delicate sheets and intricate filaments are debris from the cataclysmic death of a massive star that once lived in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. DEM L 190 — also known as LMC N49 — is the brightest supernova remnant in the Large Magellanic Cloud and lies approximately 160 000 light-years away from Earth in the constellation Dorado.

What makes this supernova remnant so visually appealing to my eye is its ghostly resemblance to a woman’s face, her hair blowing freely to the right. The original 2003 Hubble picture, shown below, has been the desktop image of my computer for almost two decades.
» Read more

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Webb makes its first detailed survey of an exoplanet’s atmosphere

9:23 am

Astronomers have now completed the first detailed survey of an exoplanet’s atmosphere using the Webb Space Telescope, looking at a gas giant about one third the mass of Jupiter about 700 light years away.

Using three of its instruments, JWST was able to observe light from the planet’s star as it filtered through WASP-39b’s atmosphere, a process known as transmission spectroscopy. This allowed a team of more than 300 astronomers to detect water, carbon monoxide, sodium, potassium and more in the planet’s atmosphere, in addition to the carbon dioxide. The gives the planet a similar composition to Saturn, although it has no detectable rings.

The team were also surprised to detect sulfur dioxide, which had appeared as a mysterious bump in early observation data. Its presence suggests a photochemical reaction is taking place in the atmosphere as light from the star hits it, similar to how our Sun produces ozone in Earth’s atmosphere. In WASP-39b’s case, light from its star, slightly smaller than the Sun, splits water in its atmosphere into hydrogen and hydroxide, which reacts with hydrogen sulfide to produce sulfur dioxide.

The data also suggested the clouds in the atmosphere are patchy, and that the planet’s formation process was not exactly as predicted.

These observations are part of a program to study 70 exoplanets during Webb’s first year of operation, using its infrared capabilities to get spectroscopy not possible in other wavelengths.

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Astronomers spot asteroid mere hours before it burned up in Earth’s atmosphere

9:29 am

For only the sixth time, astronomers this past weekend were able to image an asteroid just before it hit the Earth’s atmosphere and burned up over Canada.

The mini-asteroid, less than 3 feet (1 meter) wide, was spotted by astronomer David Rankin at Mount Lemmon Observatory in Arizona, according to SpaceWeather.com. Subsequent observations by other astronomers confirmed that the rock, coming from the direction of the main asteroid belt between the orbits of Mars and Jupiter, was on a collision course with Earth.

Only three hours after the first detection, the object, since dubbed C8FF042, sliced through the sky above Canada and landed in Lake Ontario, according to NASA.

While it is believed that most of the meteorite’s pieces that reached the ground fell into Lake Ontario, there is a chance some pieces might still be found along the south coast of the lake between Hamiliton and Niagara Falls.

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Smeared colliding galaxies

9:29 am

Smeared colliding galaxies
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Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope as part of its continuing program to collect images of unusual galaxies that had previously not been observed at high resolution.

The Arp-Madore catalogue is a collection of particularly peculiar galaxies spread throughout the southern sky, and includes a collection of subtly interacting galaxies as well as more spectacular colliding galaxies. Arp-Madore 417-391, which lies around 670 million light-years away in the constellation Eridanus in the southern celestial hemisphere, is one such galactic collision. The two galaxies have been distorted by gravity and twisted into a colossal ring, leaving the cores of the two galaxies nestled side by side.

It is likely that this collision has been going on for many millions of years, and will not be over for many millions of years to come. In the end the two galaxies will likely merge into one whose final shape cannot be predicted.

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Webb finding more galaxies in early universe than expected

10:52 am

The uncertainty of science: Astronomers using the Webb Space Telescope are finding in very early universe many more galaxies that are also far more developed then had been predicted.

The Webb observations nudge astronomers toward a consensus that an unusual number of galaxies in the early universe were so much brighter than expected. This will make it easier for Webb to find even more early galaxies in subsequent deep sky surveys, say researchers.

“We’ve nailed something that is incredibly fascinating. These galaxies would have had to have started coming together maybe just 100 million years after the big bang. Nobody expected that the dark ages would have ended so early,” said Garth Illingworth of the University of California at Santa Cruz, a member of the Naidu/Oesch team. “The primal universe would have been just one hundredth its current age. It’s a sliver of time in the 13.8 billion-year-old evolving cosmos.”

Erica Nelson of the University of Colorado in Boulder, a member of the Naidu/Oesch team, noted that “our team was struck by being able to measure the shapes of these first galaxies; their calm, orderly disks question our understanding of how the first galaxies formed in the crowded, chaotic early universe.”

The galaxies are smaller, more compact than present day galaxies, and appear to be forming stars at a tremendous rate. Because their distances, presently estimated, still need to be confirmed by spectroscopy, these conclusions remain somewhat tentative though quite alluring.

We should not be surprised if in the next two years data from Webb will overturn almost all the theories that presently exist about the Big Bang and its immediate aftermath.

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A hidden baby star, seen in infrared

9:44 am

A hidden baby star, seen in infrared
Click for original image.

Using the Webb Space Telescope, astronomers have obtained a new high resolution infrared false color view of the bi-polar jets of a new solar system and star, hidden within its dark cloud of dust.

That image is the photo to the right, reduced and sharpened to post here. From the press release:

NASA’s James Webb Space Telescope has revealed the once-hidden features of the protostar within the dark cloud L1527, providing insight into the beginnings of a new star. These blazing clouds within the Taurus star-forming region are only visible in infrared light, making it an ideal target for Webb’s Near-Infrared Camera (NIRCam).

The protostar itself is hidden from view within the “neck” of this hourglass shape. An edge-on protoplanetary disk is seen as a dark line across the middle of the neck. Light from the protostar leaks above and below this disk, illuminating cavities within the surrounding gas and dust.

The region’s most prevalent features, the clouds colored blue and orange in this representative-color infrared image, outline cavities created as material shoots away from the protostar and collides with surrounding matter. The colors themselves are due to layers of dust between Webb and the clouds. The blue areas are where the dust is thinnest. The thicker the layer of dust, the less blue light is able to escape, creating pockets of orange.

Scientists estimate this star is only about 100,000 years old, and is in its earliest stage of formation. That protoplanetary disk is estimated to be about the size of our solar system.

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Hubble takes a long exposure of spiral galaxy

9:12 am

A Hubble long exposure of a spiral galaxy
Click for original image.

This morning’s cool image on the right, reduced and sharpened to post here, comes courtesy of the Hubble Space Telescope.

NGC 7038 lies around 220 million light-years from Earth in the southern constellation Indus. This image portrays an especially rich and detailed view of a spiral galaxy, and exposes a huge number of distant stars and galaxies around it. That’s because it’s made from a combined 15 hours worth of Hubble time focused on NGC 7038 and collecting light. So much data indicates that this is a valuable target, and indeed, NGC 7038 has been particularly helpful to astronomers measuring distances at vast cosmic scales.

The press release focuses on how astronomers will use this data to refine the techniques they use to estimate distances to astronomical objects. However, a deep field image of this galaxy offers a wealth of other data. Note the reddish streams of dust along and between the spiral arms. This dust, as well as the bright patches in those arms likely signal star-forming regions. And I expect the details in the full resolution image, too large to make available on a webpage, would tell astronomers a lot about what is going on in the galaxy’s central regions.

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Astronomers discover a new large potentially dangerous near-Earth asteroid

9:36 am

Using a variety of ground-based telescopes, astronomers have discovered three new near-Earth asteroids orbiting the Sun but inside Earth’s orbit, with one of these asteroids having the possibility of one day in the future impacting the Earth.

An international team using the Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, a Program of NSF’s NOIRLab, has discovered three new near-Earth asteroids (NEAs) hiding in the inner Solar System, the region interior to the orbits of Earth and Venus. This is a notoriously challenging region for observations because asteroid hunters have to contend with the glare of the Sun.

By taking advantage of the brief yet favorable observing conditions during twilight, however, the astronomers found an elusive trio of NEAs. One is a 1.5-kilometer-wide asteroid called 2022 AP7, which has an orbit that may someday place it in Earth’s path. The other asteroids, called 2021 LJ4 and 2021 PH27, have orbits that safely remain completely interior to Earth’s orbit. Also of special interest to astronomers and astrophysicists, 2021 PH27 is the closest known asteroid to the Sun. As such, it has the largest general-relativity effects of any object in our Solar System and during its orbit its surface gets hot enough to melt lead.

You can read their paper here [pdf].

2002 AP7 is the largest such potentially dangerous asteroid discovered in eight years. Its present orbit however never brings it closer to the Earth than 4.4 million miles, and it will be many thousands of years before that orbit might result in an impact. This of course doesn’t prevent foolish mainstream news outlets like the New York Times to label it a “planet-killer.”

The importance of this study however is that it underlines the possibility that there might be other such asteroids lurking close to the Sun that are difficult to spot. This is a blind spot in our asteroid surveys that needs to be eliminated.

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Distant interacting galaxies

11:25 am

Interacting galaxies
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope as part of a survey of known “weird and wonderful galaxies.” This particular pair is dubbed Arp 248, and is estimated to be about 200 million light years away.

Two spiral galaxies are viewed almost face-on; they are a mix of pale blue and yellow in colour, crossed by strands of dark red dust. They lie in the upper-left and lower-right corners. A long, faint streak of pale blue joins them, extending from an arm of one galaxy and crossing the field diagonally. A small spiral galaxy, orange in colour, is visible edge-on, left of the lower galaxy.

The connecting stream indicates that these galaxies are interacting with each other, gravity drawing stars and gas from the upper galaxy towards the lower.

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Past tree ring spikes in carbon-14 were likely not caused by solar flares

9:41 am

The uncertainty of science: According to researchers, past tree ring spikes in carbon-14 found in found at five different times going back seven thousand years were likely not caused by solar flares, as previously thought.

The team behind the new research created software to analyse every available piece of data on tree rings, producing the most comprehensive research on Miyake events to date. They found that the events didn’t show a consistent relationship to the 11-year solar cycle, which is the cycle that the Sun’s magnetic field goes through. (Currently we’re heading towards the solar maximum which means more sunspots and solar flares.)

This lack of relationship to the solar cycle means that Miyake events probably aren’t due to a solar flare, as flares occur more during the solar maximum.

The scientists also found that the events lasted years, not days as one would expect by a solar flare.

You can read their paper here. The bottom line is that the cause of these spikes remains unknown.

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Lucy’s view of the Earth-Moon system during its October fly-by

8:35 am

The Earth and Moon system, as seen by Lucy
Click for original image.

Lucy's planned route
Lucy’s planned route to explore the Trojan asteroids

In the days prior to its October 16, 2022 fly-by of the Earth, the Lucy asteroid probe took several calibration images of the Earth and the Moon. The photo above, cropped, reduced, and enhanced to post here, shows both the Earth and the Moon together. From the caption:

On October 13, 2022, NASA’s Lucy spacecraft captured this image of the Earth and the Moon from a distance of 890,000 miles (1.4 million km). The image was taken as part of an instrument calibration sequence as the spacecraft approached Earth for its first of three Earth gravity assists. These Earth flybys provide Lucy with the speed required to reach the Trojan asteroids — small bodies that orbit the Sun at the same distance as Jupiter.

In the original, the Moon is so dim, compared to the Earth, that it was hard to find in the picture. I therefore brightened it considerably more than the Earth to make it easily seen above.

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A hole in space

8:48 am

A hole in space
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope and was released today as its picture of the week. From the caption:

This peculiar portrait from the NASA/ESA Hubble Space Telescope showcases NGC 1999, a reflection nebula in the constellation Orion. NGC 1999 is around 1350 light-years from Earth and lies near to the Orion Nebula, the closest region of massive star formation to Earth. NGC 1999 itself is a relic of recent star formation — it is composed of detritus left over from the formation of a newborn star.

Just like fog curling around a street lamp, reflection nebulae like NGC 1999 only shine because of the light from an embedded source. In the case of NGC 1999, this source is the aforementioned newborn star V380 Orionis which is visible at the centre of this image. The most notable aspect of NGC 1999’s appearance, however, is the conspicuous hole in its centre, which resembles an inky-black keyhole of cosmic proportions.

Once astronomers thought the black area was caused by dust, blocking the light. Now, based on a lot of new data from multiple ground- and space-based telescopes, they know that it actually is a black empty void. Why it exists however is not yet understood.

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Astronomers discover an exoplanet with the density of a marshmallow

10:18 am

Using ground-based telescopes to gather more data about an exoplanet discovered by the orbiting TESS telescope, astronomers have found that it has the density of a marshmallow.

The planet orbits a red dwarf star, the most common star in the universe, and is the “fluffiest” yet seen around this type of star.

Red dwarf stars are the smallest and dimmest members of so-called main-sequence stars — stars that convert hydrogen into helium in their cores at a steady rate. Though “cool” compared to stars like our Sun, red dwarf stars can be extremely active and erupt with powerful flares capable of stripping a planet of its atmosphere, making this star system a seemingly inhospitable location to form such a gossamer planet.

Astronomers remain puzzled how such a large fluffy planet could have formed around such a dim small star.

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Rate of micrometeorite impacts on Webb holding as expected

10:10 am

According to this Space.com article, the rate and size of micrometeorite impacts on the main mirror of the Webb Space Telescope has held steady at the rate and size expected, since the first surprisingly large micrometeorite impact in May that slightly dinged one mirror segment.

At this point, JWST has experienced a total of 33 micrometeoroid events, according to Smith’s slides. But the most damaging one came before JWST began science observations; in late May, a particularly large micrometeoroid struck the observatory’s mirror, leaving its mark on one golden hexagon. The team estimates that a strike of that size should occur about once a year, Smith said.

“So we got that at month five,” he said. “We haven’t seen another one yet, so it’s still consistent with the statistics that we expected.”

Smith noted that, at the current impact rate, Webb will still be meeting its five-year performance requirement 10 years into the mission. Scientists estimate that the observatory has enough fuel to operate for 20 years.

Meanwhile, one of Webb’s infrared cameras is not doing spectroscopy as engineers analyze the high levels of friction in a “grating wheel.” At this point it appears they still do not understand the cause of the friction, and thus have not come up with a plan for mitigating it.

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Twelve years of data from WISE

10:43 am

The Wide Field Infrared Survey Explorer (WISE) was launched in 2009 with an intended mission of two years, during which it would map the sky looking for asteroids. In 2011 NASA extended the mission, renaming the telescope for inexplicable reasons to NEOWISE (adding “Near-Earth Object” to the beginning).

In the more than a decade since, the telescope has been able to get eighteen repeated scans of the entire sky, allowing scientists to track many changes in a variety of stellar objects over time.

Yesterday NASA issued a press release celebrating this long achievement.

Every six months, NASA’s Near-Earth Object Wide Field Infrared Survey Explorer, or NEOWISE, spacecraft completes one trip halfway around the Sun, taking images in all directions. Stitched together, those images form an “all-sky” map showing the location and brightness of hundreds of millions of objects. Using 18 all-sky maps produced by the spacecraft (with the 19th and 20th to be released in March 2023), scientists have created what is essentially a time-lapse movie of the sky, revealing changes that span a decade.

There is a bit of hype in this claim. The data isn’t really useful when looked at across the entire sky. One has to zoom into particular objects to see them evolve over time. Also, many of these changes, such as with variable stars, are well known and tracked by many other telescopes.

Nonetheless, this infrared database is very valuable. It can be used for example by astronomers to identify objects that should be viewed with high resolution in the infrared, by Webb.

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Webb takes infrared image of Hubble’s Pillars of Creation

10:28 am

The Pillars of Creation, as seen by Hubble and Webb
Click for original image.

Not unexpectedly, astronomers have quickly begun aiming the Webb Space Telescope’s infrared eye at some of the most famous targets previously imaged in optical wavelengths by the Hubble Space Telescope.

The newest example is shown to the right and reduced and labeled to post here. It shows what NASA officials dubbed “The Pillars of Creation” when Hubble first photographed this nebula in 1995, with a later 2014 Hubble optical image at the top and the new 2022 Webb infrared image on the bottom. From this image’s caption:

A new, near-infrared-light view from NASA’s James Webb Space Telescope, at [bottom], helps us peer through more of the dust in this star-forming region. The thick, dusty brown pillars are no longer as opaque and many more red stars that are still forming come into view.

While the pillars of gas and dust seem darker and less penetrable in Hubble’s view [top], they appear more diaphanous in Webb’s. The background of this Hubble image is like a sunrise, beginning in yellows at the bottom, before transitioning to light green and deeper blues at the top. These colors highlight the thickness of the dust all around the pillars, which obscures many more stars in the overall region.

In contrast, the background light in Webb’s image appears in blue hues, which highlights the hydrogen atoms, and reveals an abundance of stars spread across the scene. By penetrating the dusty pillars, Webb also allows us to identify stars that have recently – or are about to – burst free. Near-infrared light can penetrate thick dust clouds, allowing us to learn so much more about this incredible scene.

While the Hubble colors attempt to mimic the colors seen by the human eye, the colors in the Webb image are all false colors, chosen by the scientists to distinguish the different infrared wavelengths produced by different features in the picture.

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The first Greek star catalog discovered hidden in medieval parchment

10:04 am

Scientists have discovered part of the first Greek star catalog created by Hipparchus — thought by many to have invented the modern field of astronomy — hidden in a medieval parchment that had been reused for other puposes.

Scholars have been searching for Hipparchus’s catalogue for centuries. James Evans, a historian of astronomy at the University of Puget Sound in Tacoma, Washington, describes the find as “rare” and “remarkable”. The extract is published online this week in the Journal for the History of Astronomy. Evans says it proves that Hipparchus, often considered the greatest astronomer of ancient Greece, really did map the heavens centuries before other known attempts. It also illuminates a crucial moment in the birth of science, when astronomers shifted from simply describing the patterns they saw in the sky to measuring and predicting them.

The manuscript came from the Greek Orthodox St Catherine’s Monastery in the Sinai Peninsula, Egypt, but most of its 146 leaves, or folios, are now owned by the Museum of the Bible in Washington DC. The pages contain the Codex Climaci Rescriptus, a collection of Syriac texts written in the tenth or eleventh centuries. But the codex is a palimpsest: parchment that was scraped clean of older text by the scribe so that it could be reused.

Using modern multi-spectral imaging, the researchers were able to decipher the older text, and determined it was almost certainly written by Hipparchus and included his star measurements.

Read the whole article at the link. It is a fascinating detective story describing the origins of modern astronomy in western civilization.

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Jets from baby stars

12:12 pm

Jets from baby stars
Click for full image.

Cool image time! The picture to the right, rotated and reduced to post here, was taken across multiple wavelengths by the Hubble Space Telescope and shows two different Herbig–Haro objects (HH 1 at the top and HH 2 on the bottom). Herbig-Haro objects are the bright cloud clumps found near newly formed baby stars. These particular clouds are about 1,250 light years away. The jets flowing away from HH 1 are speeding away at about 250 miles per second.

Note that the baby stars themselves are not visible, buried in the dust that surrounds them. The bright star in the upper right is an unrelated foreground star.

In the case of HH 1/2, two groups of astronomers requested Hubble observations for two different studies. The first delved into the structure and motion of the Herbig–Haro objects visible in this image, giving astronomers a better understanding of the physical processes occurring when outflows from young stars collide with surrounding gas and dust. The second study instead investigated the outflows themselves to lay the groundwork for future observations with the NASA/ESA/CSA James Webb Space Telescope. Webb, with its ability to peer past the clouds of dust enveloping young stars, will revolutionise the study of outflows from young stars.

There is a lot of complexity here that this image only hints at. Note for example the smaller cloud objects near HH1, the shape of which suggest a shaping by some interstellar wind.

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Two solar eclipses coming to the U.S. next year

12:47 pm

The next eclipses to cross the U.S.
Map by Michael Zeiler (GreatAmericanEclipse.com). Click for original.

The U.S. public will get to see two different solar eclipses during a six month period, starting one year from today.

The map to the right, cropped and reduced to post here, shows the dates and the path of both eclipses.

On 14 October 2023, anyone under clear skies within a path that sweeps from Oregon to Texas and then through parts of Central and South America will see an annular (“ring”) eclipse. Just six months later, on 8 April 2024, a total solar eclipse will sweep from Mexico to Texas to the Canadian Maritimes, plunging day into night and revealing the magnificent solar corona for anyone fortunate to be within the path of totality and under clear skies. Nearly everyone in North America will have a partial solar eclipse both days.

As always with eclipses, great care must be taken to watch it. With the 2017 eclipse Diane and I had good filters, but even so I noticed my eyes were very tired for several days afterward.

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Final decision: Arecibo will not be rebuilt

3:34 pm

The National Science Foundation has made it official: It will not rebuild the Arecibo Observatory in Puerto Rico, though it will fund the facility as an education center instead.

Now, the National Science Foundation (NSF), which owns the site, has determined that despite scientists’ pleas, Arecibo Observatory won’t be getting any new telescope to replace the loss. The new education project also doesn’t include any long-term funding for the instruments that remain operational at the observatory, including a 40-foot (12 m) radio dish and a lidar system.

…Instead, the NSF intends to build on the observatory’s legacy as a key educational institution in Puerto Rico by transforming the site into a hub for science, technology, engineering and math (STEM) education, due to open in 2023, according to a statement. The observatory is also home to the Ángel Ramos Foundation Science and Visitor Center, which opened in 1997.

It seems unclear how this education center will function. Will it be a school that students attend? Or simply a type of museum with a visitors center? This new plan appears to call for about $2 million per year in funding, which does not appear enough to do much of anything, other than to keep the lights on and hang some pretty astronomy pictures on the walls.

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