Tag: astronomy

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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Interstellar clouds backlit by nearby massive star

1:27 pm

Interstellar clouds backlit by nearby massive star
Click for full image.

Cool image time! The photo to the right, cropped and reduce to post here, was taken by the Hubble Space Telescope of what astronomers believe is a newly formed massive star about 9,000 light years away that has periodically spewed out material during eruptions.

The scientists hope to use Hubble to determine the speed in which this material is flying away from the star by taking pictures at intervals and then measuring the amount of change from image to image. This data will also allow the scientists to better gauge the distance to this star, as well as its actual mass, information that will help them better understand what is happening.

I highlight this picture however simply because of its beauty. The interstellar clouds on the left are all apparently backlit by the brightest star on the right, and thus their shape is easy to perceive.

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Webb takes its first infrared image of Mars

9:12 am

Webb's first infrared image of Mars
Click for full image.

Astronomers have now released the the James Webb Space Telescope’s first infrared image of Mars, taken on September 5, 2022.

The image to the right, cropped and reduced to post here, shows some of the data obtained. Because Mars is so close, it is actually too bright for Webb’s instruments. To get any data, the exposures were very very short, and still the brightest areas — as indicated by large areas of yellow — are overexposed. The cause of the different brightness of Hellas Basin, however, is not simply because the basin — the deepest point on Mars — is cooler.

As light emitted by the planet passes through Mars’ atmosphere, some gets absorbed by carbon dioxide (CO2) molecules. The Hellas Basin – which is the largest well-preserved impact structure on Mars, spanning more than 1,200 miles (2,000 kilometers) – appears darker than the surroundings because of this effect. “This is actually not a thermal effect at Hellas,” explained the principal investigator, Geronimo Villanueva of NASA’s Goddard Space Flight Center, who designed these Webb observations. “The Hellas Basin is a lower altitude, and thus experiences higher air pressure. That higher pressure leads to a suppression of the thermal emission at this particular wavelength range [4.1-4.4 microns] due to an effect called pressure broadening. It will be very interesting to tease apart these competing effects in these data.”

The NASA press release says the scientists are preparing a paper analyzing the spectral data and what it revealed about “dust, icy clouds, what kind of rocks are on the planet’s surface, and the composition of the atmosphere,” I suspect however that Webb’s capabilities for studying Mars are much more limited than implied, and that it will over time take much fewer images of the red planet, compared to Hubble.

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New theory: Saturn’s rings came from a lost and destroyed moon

9:24 am

The uncertainty of science: According to a new computer simulation, scientists have proposed that the reason Saturn’s rings are tilted 27 degrees is because they were created by the destruction of a moon 160 million years ago, an event that was also linked to the way the orbits of Saturn and Neptune interact, combined with the on-going slow evolutionary changes in Titan’s orbit around Saturn.

Wisdom and his colleagues believe Saturn acquired its tilt because of a peculiar synchronicity: the precession of Saturn’s spin axis—the way it wobbles like a top with a particular rhythm—is suspiciously in tune with a precession in Neptune’s orbit. If Saturn and Neptune were trapped in this resonance, Saturn’s tilt would be “kind of vulnerable to other forces that could cause it to change,” says Rola Dbouk, an MIT graduate student in planetary science. In 2020, Cassini scientists discovered what the study team thinks is that external stimulus: Titan, Saturn’s largest moon, is migrating away from Saturn by 11 centimeters a year. In a study published today in Science, Dbouk, Wisdom, and colleagues show how Titan’s migration, in combination with the Saturn-Neptune resonance, could have ratcheted up Saturn’s tilt over the course of 1 billion years.

The work also yielded a potential explanation for the origin of Saturn’s rings. Using Cassini’s measurements of Saturn’s gravitational fields to model the planet’s interior structure, the researchers refined calculations for the wobble of Saturn’s spin axis and found it is no longer in sync with Neptune. “Something kicked it out of the resonance,” Dbouk says. They first ruled out the possibility that chaotic changes in the orbits of some of the largest of Saturn’s dozens of moons could be responsible. But when they added another moon to the mix, things got interesting.

In simulations, the researchers included an object about the size of Iapetus, Saturn’s third largest moon, orbiting about 43 Saturn radii out—between the orbits of Titan and Iapetus. They found this moon could have provided the necessary nudge to the resonance if it were suddenly knocked from its orbit because of chaotic interactions with its neighbors about 160 million years ago.

To say that this theory is uncertain is no different that saying the sky is blue. It is so uncertain that it is difficult to take it seriously. It could be right, but as one scientist quoted at the article noted, there is no way to test it.

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Overlapping galaxies

9:22 am

Overlapping galaxies, as seen by Hubble
Click for full image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken by astronomers using the Hubble Space Telescope, and captures two galaxies that happen to overlap in their line of sight to Earth.

The two galaxies, which have the uninspiring names SDSS J115331 and LEDA 2073461, lie more than a billion light-years from Earth. Despite appearing to collide in this image, the alignment of the two galaxies is likely just by chance — the two are not actually interacting.

This image was taken as part of the citizen-scientist project dubbed Galaxy Zoo, whereby volunteers review lower resolution images of strange-looking galaxies and propose the best for Hubble higher resolution imaging.

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Astronomers propose method for predicting the stars that will go supernovae

9:12 am

The uncertainty of science: Using a computer model based on the most recent data that suggests red supergiant stars like Betelgeuse are the kind of stars that produce certain kinds of supernovae, astronomers now think they have a method for predicting which of those stars are about to go supernovae.

You can read the science paper here. From the link above:

In a few examples, astronomers have looked back at old catalogs and found images of the stars before they exploded, and they all seem to be red supergiants like Betelgeuse. That’s a clear indication that those kinds of stars are supernova candidates, ready to go off at a moment’s notice.

The stars that result in these kinds of supernovas are thought to have dense shrouds of material surrounding them before they explode. These shrouds are orders of magnitude denser than what’s measured around Betelgeuse.

More importantly, the data suggests that once this shroud of material forms, the supernova will follow, in just a few years. As the scientists conclude in their paper:

The final overarching conclusion we can make from this work is that, shortly before core-collapse, [red supergiants] must undergo some prodigious mass-losing event which radically alters the appearance of the star. Therefore, the signature of an imminent explosion should be a dramatic change in the progenitor stars’ optical – near-IR photometry on timescales of less than a month. Such a signature should be detectable in the coming era of wide-field short cadence photometry. [emphasis mine]

Near-IR (infrared) photometry is exactly in the wavelengths in which the James Webb Space Telescope operates. Thus, if it is lucky and sees this kind of star in an image, and a supernova follows shortly thereafter, this theory will have been proven correct.

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Inouye Solar Telescope begins science operations

10:07 am

The National Science Foundation yesterday announced the inauguration of science operations of the Daniel K. Inouye Solar Telescope in Hawaii.

The sample first images provided at the link are excellent, but rather than show this telescope’s abilities, they instead illustrate the absurdity of spending millions to build a ground-based telescope. None compare with the spectacular high resolution solar images being produced today from the myriad of solar telescopes in space.

Moreover, the history of this telescope tells us much about the bankrupt nature of all modern government projects:

Over 25 years ago, the NSF invested in creating a world-leading, ground-based solar observatory to confront the most pressing questions in solar physics and space weather events that impact Earth. This vision, executed by the Association of Universities for Research in Astronomy (AURA) through the NSF’s National Solar Observatory (NSO), was realized during the formal inauguration of the Inouye Solar Telescope. [emphasis mine]

It took our modern incompetent federal government a quarter century to build this single telescope. Compare that with the construction of the solar telescopes it is replacing. They were conceived, designed, and built in much less than a decade back in the early 1960s. And cost less too.

The press release at the link also spends a lot of space touting “diversity” and “Native Hawaiian” cultural needs, which really have nothing to do with the study of the Sun. That focus tells us how misguided our government has become, and how it is using its coercive power to drag us all along down that foolish path towards hell.

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Webb’s infrared view of the Tarantula Nebula

9:55 am

Two views of the Tarantula Nebula by Webb
Click for original image.

The two images to the right, reduced and annotated to post here, were released today by the science team of the James Webb Space Telescope, and show two different views of the Tarantula Nebula, located 161,000 light years away in the Large Magellanic Cloud.

It is home to the hottest, most massive stars known. Astronomers focused three of Webb’s high-resolution infrared instruments on the Tarantula. Viewed with Webb’s Near-Infrared Camera (NIRCam) [top], the region resembles a burrowing tarantula’s home, lined with its silk. The nebula’s cavity centered in the NIRCam image has been hollowed out by blistering radiation from a cluster of massive young stars, which sparkle pale blue in the image. Only the densest surrounding areas of the nebula resist erosion by these stars’ powerful stellar winds, forming pillars that appear to point back toward the cluster. These pillars contain forming protostars, which will eventually emerge from their dusty cocoons and take their turn shaping the nebula.

…The region takes on a different appearance when viewed in the longer infrared wavelengths detected by Webb’s Mid-infrared Instrument (MIRI) [bottom]. The hot stars fade, and the cooler gas and dust glow. Within the stellar nursery clouds, points of light indicate embedded protostars, still gaining mass. While shorter wavelengths of light are absorbed or scattered by dust grains in the nebula, and therefore never reach Webb to be detected, longer mid-infrared wavelengths penetrate that dust, ultimately revealing a previously unseen cosmic environment.

As with all images from Webb, these are false color, as the telescope views the infrared heat produced by stars and galaxies and interstellar clouds, not the optical light our eyes see. Thus, the scientists assign different colors to the range of wavelengths each instrument on Webb captures.

These photos once again illustrate Webb’s value. It will provide a new layer of data to supplement the basic visual information provided by the Hubble Space Telescope, allowing scientists to better understand the puzzles we see in the optical.

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