Tag: astronomy

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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The known near Earth asteroid catalog now tops 30,000

9:35 am

Chart of NEA's discovered over time

The catalog of known near Earth asteroids that have been identified using a number of survey telescopes in space and on the Earth now totals 30,039. As defined at the link:

An asteroid is called a near-Earth asteroid (NEA) when its trajectory brings it within 1.3 Astronomical Units (au) of the Sun. 1 au is the distance between the Sun and Earth, and so NEAs can come within at least 0.3 au, 45 million km, of our planet’s orbit.

Currently, near-Earth asteroids make up about a third of the roughly one million asteroids discovered so far in the Solar System. Most of them reside in the asteroid belt between Jupiter and Mars.

NEAs are also called NEOs (Near Earth Objects). The chart above, produced by the Center for NEO Studies which tracks these objects, shows the number of NEAs discovered over time.

Of the 30,039 now known, about 1,400 have orbits with “a non-zero” chance of hitting the Earth. None however will do so in the next hundred years at least.

Though the pace of discovery is vastly improving — as indicated by the steep rise in the curve in the graph — only when that curve begins to flatten out will we know that we are getting close to having a more-or-less complete survey of these objects.

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Shells of dust surrounding massive binary star

10:07 am

Webb infrared image of dust shells surrounding binary star system
Click for full image.

Cool image time! Using the Webb telescope, astronomers have detected a series of concentric shells surrounding the massive binary star dubbed Wolf-Rayet 140.

The infrared image to the right shows these shells quite clearly. As noted by astronomer Ryan Lau:

“On the night that my team’s Early Release Science observations of the dust-forming massive binary star Wolf-Rayet (WR) 140 were taken, I was puzzled by what I saw in the preview images from the Mid-Infrared Instrument (MIRI). There seemed to be a strange-looking diffraction pattern, and I worried that it was a visual effect created by the stars’ extreme brightness. However, as soon as I downloaded the final data I realized that I was not looking at a diffraction pattern, but instead rings of dust surrounding WR 140 – at least 17 of them.

“I was amazed. Although they resemble rings in the image, the true 3D geometry of those semi-circular features is better described as a shell. The shells of dust are formed each time the stars reach a point in their orbit where they are closest to each other and their stellar winds interact. The even spacing between the shells indicates that dust formation events are occurring like clockwork, once in each eight-year orbit. In this case, the 17 shells can be counted like tree rings, showing more than 130 years of dust formation. Our confidence in this interpretation of the image was strengthened by comparing our findings to the geometric dust models by Yinuo Han, a doctoral student at the University of Cambridge, which showed a near-perfect match to our observations.

Furthermore, the spectroscopy from Webb says these dust shells are carbon-enriched, showing that the dust released by these aged massive stars is a significant source of the carbon in the universe, the fundamental atom needed for life.

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DART’s impact shortened Dimorphus’s orbit around Didymos by 32 minutes

5:51 pm

LICIACube Explorer image of DART impact
LICIACube Explorer image just after the DART
impact. Dimorphus is the blob near the top.

After two weeks of analyzing the orbit of Dimorphus around its parent asteroid Didymos, astronomers have determined that the impact of DART on Dimorphus shortened its orbit by 32 minutes.

Prior to DART’s impact, it took Dimorphos 11 hours and 55 minutes to orbit its larger parent asteroid, Didymos. Since DART’s intentional collision with Dimorphos on Sept. 26, astronomers have been using telescopes on Earth to measure how much that time has changed. Now, the investigation team has confirmed the spacecraft’s impact altered Dimorphos’ orbit around Didymos by 32 minutes, shortening the 11 hour and 55-minute orbit to 11 hours and 23 minutes. This measurement has a margin of uncertainty of approximately plus or minus 2 minutes.

Before its encounter, NASA had defined a minimum successful orbit period change of Dimorphos as change of 73 seconds or more. This early data show DART surpassed this minimum benchmark by more than 25 times.

It also appears the ejecta from the impact — much greater than expected — helped propel Dimorphus, a result that I think was also not expected.

Researchers are now shifting to studying the debris and asteroid itself, to better understand what happened as well as the nature of Dimorphus itself. This will also include a European probe dubbed Hera that will launch in 2024 an dvisit both asteroids in 2026.

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Webb gets first direct infrared image of exoplanet

10:21 am

Exoplanet as seen in the infrared by Webb

Using the Webb Space Telescope, scientists have obtained that telescope’s first direct infrared image of an exoplanet, covering four different wavelengths.

The image to the right is from the wavelength image with the least distortion (formed by Webb’s own optics and the shape of its mirror and indicated by the faint ring surrounding the planet). The star indicates the masked location of the star itself.

The planet is about seven times the mass of Jupiter and lies more than 100 times farther from its star than Earth sits from the sun, direct observations of exoplanet HIP 65426 b show. It’s also young, about 10 million or 20 million years old, compared with the more than 4-billion-year-old Earth.

You can download the full research paper here.

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Chandra takes an X-ray look at early Webb infrared observations

9:54 am

Chandra's X-ray vision of the Cartwheel Galaxy
Chandra’s X-ray view of the Cartwheel Galaxy

Webb's view of the Cartwheel Galaxy
Webb’s infrared view of the Cartwheel Galaxy
Click for full image.

Hubble's optical view of the Cartwheel Galaxy
Hubble’s optical view of the Cartwheel Galaxy. Click for original image.

Astronomers have now taken X-ray images using the orbital Chandra X-ray Observatory of four of the first Webb Space Telescope observations. The four targets were the Cartwheel Galaxy, Stephan’s Quintet, galaxy cluster SMACS 0723.3–7327, and the Carina Nebula.

The three images to the right illustrate the importance of studying astronomy across the entire electromagnetic spectrum. Each shows the Cartwheel Galaxy as seen by three of the world’s most important space-based telescopes, each looking at the galaxy in a different wavelength.

The top picture is Chandra’s new X-ray observations. As the press release notes,

Chandra data generally show higher-energy phenomena (like superheated gas and the remnants of exploded stars) than Webb’s infrared view. … X-rays seen by Chandra (blue and purple) come from superheated gas, individual exploded stars, and neutron stars and black holes pulling material from companion stars.

The middle picture was produced by Webb, shortly after the start of its science operations. It looks at the galaxy in the infrared.

In this near- and mid-infrared composite image, MIRI data are colored red while NIRCam data are colored blue, orange, and yellow. Amidst the red swirls of dust, there are many individual blue dots, which represent individual stars or pockets of star formation. NIRCam also defines the difference between the older star populations and dense dust in the core and the younger star populations outside of it.

The bottom picture was taken by the Hubble Space Telescope in 1995. I have rotated the image to match the others. It looks at the galaxy in optical wavelengths, the wavelengths that our eyes perceive.

Note how bright the central galactic region is in the infrared and optical, but is invisible in X-rays. Chandra is telling us that all the most active regions in the Cartwheel are located in that outer ring, not in its center.

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Two days after DART’s impact of Dimorphus, ejected dust extends like a comet tail out more than 6,000 miles

12:23 pm

Dust tail from Dimorphus two days after DART impact
Click for full image.

Using a telescope in Chile, astronomers photographed the ejecta two days after the impact of DART into the 525-foot-wide asteroid Dimorphus, and detected a tail of dust extending out more than 6,000 miles.

The picture to the right, cropped and reduced to post here, shows that tail.

In this new image, the dust trail — the ejecta that has been pushed away by the Sun’s radiation pressure, not unlike the tail of a comet — can be seen stretching from the center to the right-hand edge of the field of view. … At Didymos’s distance from Earth at the time of the observation, that would equate to at least 10,000 kilometers (6000 miles) from the point of impact.

Didymos is the larger parent asteroid that Dimorphus orbits.

It is still too soon to get the numbers on how Dimorphus’s path in space was changed by that impact. In fact, we still really don’t have a clear idea what is left of Dimophus itself. The ejecta cloud needs to clear somewhat to see what’s hidden inside it.

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Interacting galaxies

9:02 am

Interacting galaxies
Click for full image.

The news is light this morning, so this cool image will be the first of three. The picture to the right, cropped and reduced to post here, was taken by the Hubble Space Telescope and released today. From the caption:

The two interacting galaxies making up the pair known as Arp-Madore 608-333 seem to float side by side in this image from the NASA/ESA Hubble Space Telescope. Though they appear serene and unperturbed, the two are subtly warping one another through a mutual gravitational interaction that is disrupting and distorting both galaxies.

I did a search for any research of this galaxy pair, and found that its identification was only part of a larger survey, with only a little research done on its spectroscopy. Thus, I can’t tell you the size or distance, or how far apart from each other these galaxies lie.

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SpaceX and Jared Isaacman offer private mission to NASA to raise Hubble’s orbit

9:44 am

Capitalism in space: In a press release issued yesterday, NASA revealed that it has signed an unfunded agreement with SpaceX and Jared Isaacman’s Polaris program (which has purchased a series of manned missions on Dragon) to study the possibility of sending one of those private manned missions to the Hubble Space Telescope to raise its orbit.

SpaceX – in partnership with the Polaris Program – proposed this study to better understand the technical challenges associated with servicing missions. This study is non-exclusive, and other companies may propose similar studies with different rockets or spacecraft as their model.

Teams expect the study to take up to six months, collecting technical data from both Hubble and the SpaceX Dragon spacecraft. This data will help determine whether it would be possible to safely rendezvous, dock, and move the telescope into a more stable orbit.

In my book describing the history of the people who created Hubble, The Universe in a Mirror, I repeatedly noted how throughout its history people have tried to kill it, first in the design phase, then in the budget, then during construction, then after it was launched and the mirror was found to be ground incorrectly, and then after the Columbia accident when NASA management tried to cancel its last shuttle servicing mission.

Every attempt failed. As I have noted in that book and many times since its publication, Hubble is a telescope that will not die. NASA has for years intended to launch a mission to de-orbit it when its orbit had decayed enough that it was unstable. I’ve always said that when that time came, someone would propose and push for a mission to instead raise that orbit.

That prediction is now coming true. Though no robot arm exists yet for Dragon to use to grab Hubble in any rendezvous attempt, creating one is hardly difficult. At that point raising the telescope’s orbit becomes relatively trivial.

Whether such a mission could do more, such as replace Hubble’s ailing gyroscopes, is unknown. It would be foolish however not to review that possibility as well.

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Initial Webb results revised because telescope wasn’t yet fully calibrated

10:02 am

The uncertainty of science: Though it appears that no results will have to be abandoned, the scientists who published some of the very first results from the Webb Space Telescope have been scrambling to adjust and revise their papers because the telescope is only now getting fully calibrated.

“This caused a little bit of panic,” says Nathan Adams, an astronomer at the University of Manchester, UK, who, along with his colleagues, pointed out the problem in a 9 August update to a preprint they had posted in late July3. “For those including myself who had written a paper within the first two weeks, it was a bit of — ‘Oh no, is everything that we’ve done wrong, does it all need to go in the bin?’”

To try to standardize all the measurements, the STScI is working through a detailed plan to point Webb at several types of well-understood star, and observe them with every detector in every mode for every instrument on the telescope4. “It just takes a while,” says Karl Gordon, an astronomer at the STScI who helps lead the effort.

In the meantime, astronomers have been reworking manuscripts that describe distant galaxies on the basis of Webb data. “Everyone’s gone back over and had a second look, and it’s not as bad as we thought,” Adams says. Many of the most exciting distant-galaxy candidates still seem to be at or near the distance originally estimated. But other preliminary studies, such as those that draw conclusions about the early Universe by comparing large numbers of faint galaxies, might not stand the test of time. Other fields of research, such as planetary studies, are not affected as much because they depend less on these preliminary brightness measurements.

Overall, it does not appear the more precise calibrations will change much of signficance, since most of the earliest observations were simply that, observations, not theoretical. Because the distance estimates remain largely unchanged however the theorists are left with the same conundrum: The age and apparent nature of the most distant objects does not seem to fit with what the theories had predicted Webb would see.

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Hubble & Webb make first coordinated observations, tracking DART impact of Dimorphus

9:50 am

Webb and Hubble together look at DART impact of Dimorphus
Click for full image.

For the first time scientists have used both the Hubble Space Telescope and the James Webb Space Telescope to observe the same astronomical event, in this case the impact of the DART spacecraft on the asteroid Dimorphus on September 26, 2022.

The two images to the right show the asteroid several hours after impact. Both telescopes also captured images before the impact as well. From the press release:

Observations from Webb and Hubble together will allow scientists to gain knowledge about the nature of the surface of Dimorphos, how much material was ejected by the collision, and how fast it was ejected. Additionally, Webb and Hubble captured the impact in different wavelengths of light – Webb in infrared and Hubble in visible. Observing the impact across a wide array of wavelengths will reveal the distribution of particle sizes in the expanding dust cloud, helping to determine whether it threw off lots of big chunks or mostly fine dust. Combining this information, along with ground-based telescope observations, will help scientists to understand how effectively a kinetic impact can modify an asteroid’s orbit.

When Webb was first conceived in the late 1990s, it was exactly for this reason, to combine Hubble’s optical vision with Webb’s infrared view. Though more than a decade late, it has finally happened.

It will be months before scientists begin to decipher the data produced by all the telescopes and spacecraft used to observe the DART impact. What we are seeing now are merely hints at what has been learned.

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Celestron to modify commercial amateur telescope for space use

9:19 am

Capitalism in space: Amateur telescope manufacturer Celestron has signed a deal to adapt one of its more expensive ground-based telescopes for use in space.

Trans Astronautica Corp. announced an agreement Sept. 27 with telescope manufacturer Celestron to develop a space-qualified version of the company’s Rowe-Ackermann Schmidt Astrograph (RASA) ground-based telescope. “We’ve been using Celestron’s RASA telescopes in our space domain awareness and asteroid prospecting systems, and we found them to be very affordable, high-quality optical systems,” Joel Sercel, TransAstra founder and CEO, told SpaceNews. “We looked at the designs and we realized it would not be that hard to adapt them for space use.”

Over the next year, TransAstra plans to modify the RASA telescope design and substitute materials to produce a telescope that can withstand radiation exposure, temperature swings, and the vibration and shock loads of space launch.

TransAstra provides tracking data on space junk to both the commercial and defense industry. It also has a new deal to use its telescopes to provide schools use of these telescopes for educational purposes. The goal is to put this capability into orbit.

The future ramifications however are profound. Once Celestron has a commercial relatively inexpensive telescope capable of operating in space (or on the Moon), it will not take long before customers begin lining up eager to buy and launch it. Think about it: though there will be engineering issues to overcome, the cost of placing one of these telescopes on one of the new commercial lunar landers for operation on the Moon will not be far beyond the budgets of many amateur astronomers, some of whom spend hundreds of thousands of dollars on their own ground-based observatories.

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First ground-based telescope view of DART impact on Dimorphus

10:10 am

LICIACube Explorer image of DART impact

We now have the first ground-based images of the DART impact on the 525-foot-wide asteroid Dimorphus yesterday, captured by the Hawaiian telescope ATLAS.

You need to watch the video of the full sequence of images, available here, to get a true sense of the impact. The cloud of material quickly expands to about twice the asteroid’s size, then dissipates away, with the remaining asteroid now appearing larger (?). That larger size could be caused by a remaining cloud of material that still needs to settle back to the surface.

More images have been released by a Chinese telescope. Also, the first images from the Italian cubesat LICIACube Explorer, flying in parallel with DART, have been released. I have posted one to the right. The large blob near the center is the parent half-mile-wide asteroid, Didymos. Dimorphus is buried in the debris cloud above and slightly to the right.

Hat tip stringer Jay for the links to these images.

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DART hits Dimorphus

4:42 pm

Didymos and Dimorphus

Dimorphus

The surface of Dimorphus

The probe DART today successfully impacted the small 525-foot-wide asteroid Dimorphus. From the data produced engineers will calculate how much that impact changed Dimorphus’ orbit around it parent asteroid, half-mile-wide Didymos.

The three images to the right give a sense of the approach and impact.

The first, at 2 minutes and 30 seconds from impact, shows Didymos in the left bottom corner. You can actually see individual boulders on its surface. At this distance and resolution is is unclear whether it is a rubble pile or a more solid body. Dimorphus is no longer a mere dot, but no surface features can yet be discerned.

The second image, only seventeen seconds before DART crashed into Dimorphus, shows us the entire asteroid. Though it appears to be a pile of rocks, it also appears less of a rubble pile than both Ryugu and Bennu, visited by probes in 2019 and 2020. Those rubble-piles had almost no smooth surface areas. Dimorphus however at this distance and resolution does appear to have a lot of areas where the surface is relatively smooth, suggesting its structure is more solid than a rubble pile.

At only 525 feet across, some of those bigger boulders are about 50 to 60 feet in diameter.

The white dot in the center of Dimorphus marks the rocks seen in the third image, taken about five seconds before impact. At this resolution so close to the surface, it appears the smooth areas are actually made up of many tiny pebbles and dust.

The biggest rock in the center of the picture is probably between ten to twenty feet in diameter.

The primary data from this mission will not be available for a few weeks. Scientists have to observe both asteroids to see how much, if at all, Dimorphus’s orbit was shifted by the impact. Also, the images from the Italian cubesat, LICIACube Explorer, which was flying parallel to DART and taking pictures of the impact, plume, and back side of Dimorphus, won’t be available until later this week. Those images should give us a measure of the spacecraft’s effect on the asteroid. They will also reveal a lot more about the asteroid’s geology.

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A galaxy slowly being eaten by its black hole

10:16 am

Spiral galaxy
Click for full image.

Cool image time! The photo to the right, rotated and reduced to post here, was taken by the Hubble Space Telescope. From the caption:

NGC 5495, which lies around 300 million light-years from Earth in the constellation Hydra, is a Seyfert galaxy, a type of galaxy with a particularly bright central region. These luminous cores — known to astronomers as active galactic nuclei — are dominated by the light emitted by dust and gas falling into a supermassive black hole. This image is drawn from a series of observations captured by astronomers studying supermassive black holes lurking in the hearts of other galaxies.

Essentially Seyfert galaxies are galaxies whose central supermassive black hole has become dominant, large enough that its gravity is slowly eating up the rest of the galaxy. As it increasingly swallows stars and gas, the black hole emits more and more energy, thus becoming an active galactic nuclei.

Two stars from our own galaxy also dominate this picture, one inside and to the right of the galaxy’s center, and the other the bright star at the bottom of the picture, both identified by the diffraction spikes.

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Webb’s first infrared image of Neptune

9:30 am

Webb's infrared view of Neptune
Click for full image.

The science team for the James Webb Space Telescope today released that telescope’s first infrared image of Neptune.

That image is to the right, cropped and reduced slightly to post here. It is, as the press release touts, the best view in decades of Neptune’s rings. From the caption:

The most prominent features of Neptune’s atmosphere in this image are a series of bright patches in the planet’s southern hemisphere that represent high-altitude methane-ice clouds. More subtly, a thin line of brightness circling the planet’s equator could be a visual signature of global atmospheric circulation that powers Neptune’s winds and storms. Additionally, for the first time, Webb has teased out a continuous band of high-latitude clouds surrounding a previously-known vortex at Neptune’s southern pole.

The dots around the gas giant are the heat signatures of seven of its fourteen moons.

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Webb instrument has technical issue partly preventing its use

9:31 am

Because a an issue with the mid-infrared instrument (MIRI) on the James Webb Space Telescope, the telescope’s engineering team has paused use of that instrument while it reviews the situation.

On Aug. 24, a mechanism that supports one of these modes, known as medium-resolution spectroscopy (MRS), exhibited what appears to be increased friction during setup for a science observation. This mechanism is a grating wheel that allows scientists to select between short, medium, and longer wavelengths when making observations using the MRS mode. Following preliminary health checks and investigations into the issue, an anomaly review board was convened Sept. 6 to assess the best path forward.

The Webb team has paused in scheduling observations using this particular observing mode while they continue to analyze its behavior and are currently developing strategies to resume MRS observations as soon as possible. The observatory is in good health, and MIRI’s other three observing modes – imaging, low-resolution spectroscopy, and coronagraphy – are operating normally and remain available for science observations.

I am quoting almost entirely NASA’s short announcement. The announcement is vague, confusing, and (quite typically) written to minimize the reality of the issue. I can’t figure out how MIRI’s other observing modes are available if they have paused use of a mechanism that allows them to choose modes.

Regardless, Webb is awful young to have this kind of problem.

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