Tag: astronomy

VLT snaps image of double asteroid zipping past Earth

9:04 am

Double asteroid imaged by VLT

The Very Large Telescope (VLT) in Chile was successfully able to photograph the double asteroid that flew past the Earth on May 25 at a distance of 3.2 million miles and a speed of 43 thousand miles per hour.

The left image on the right is the raw image, while the right image is their reconstruction after applying adaptive-optics (AO) to the raw image. From the press release:

Bin Yang, VLT astronomer, declared “When we saw the satellite in the AO-corrected images, we were extremely thrilled. At that moment, we felt that all the pain, all the efforts were worth it.” Mathias Jones, another VLT astronomer involved in these observations, elaborated on the difficulties. “During the observations the atmospheric conditions were a bit unstable. In addition, the asteroid was relatively faint and moving very fast in the sky, making these observations particularly challenging, and causing the AO system to crash several times. It was great to see our hard work pay off despite the difficulties!”

To put it mildly, that right image is a fantasy. Astronomers love to tout the wonders of adaptive optics, but no matter how good it might be, it still is garbage-in-garbage-out, a computer simulation based on their guess at what the object would look like if there was no atmosphere in the way. In this particular case, they are being especially fantastic, and guaranteed to be wrong. It is impossible for them to extrapolate such minute surface details from the fuzzy image on the left.

Still, getting an image of this asteroid as it zipped by at that speed using such a large telescope is an achievement, and bodes well for the use of ground-based astronomy of near Earth asteroids.

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First movie of solar eclipse rediscovered

9:56 am

The first movie ever made of a solar eclipse, taken in 1900, has been rediscovered and restored.

The film was taken by British magician turned pioneering filmmaker Nevil Maskelyne on an expedition by the British Astronomical Association to North Carolina on 28 May, 1900. This was Maskelyne’s second attempt to capture a solar eclipse. In 1898 he travelled to India to photograph an eclipse where succeeded but the film can was stolen on his return journey home. It was not an easy feat to film. Maskelyne had to make a special telescopic adapter for his camera to capture the event. This is the only film by Maskelyne that we know to have survived.

I have embedded the movie below the fold.
» Read more

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Three exocomets found circling Beta Pictoris

7:31 am

The uncertainty of science: By analyzing data from the new space telescope TESS, astronomers think they have identified three exocomets orbiting the nearby star Beta Pictoris.

Why do I label this uncertain? Let the scientists themselves illustrate my doubt:

Sebastian Zieba, Master’s student in the team of Konstanze Zwintz at the Institute of Astro- and Particle Physics at the University of Innsbruck, discovered the signal of the exocomets when he investigated the TESS light curve of Beta Pictoris in March this year. “The data showed a significant decrease in the intensity of the light of the observed star. These variations due to darkening by an object in the star’s orbit can clearly be related to a comet,” Sebastian Zieba and Konstanze Zwintz explain the sensational discovery.

The press release provides no other information about why they think this darkening is because of comets rather than exoplanets or some other phenomenon. Based on this alone, I find this report very doubtful and highly speculative.

In related news, astronomers now claim they have detected eighteen more Earth-sized exoplanets in the data produced by Kepler, and they have done so by applying new algorithms to the data.

Large planets tend to produce deep and clear brightness variations of their host stars so that the subtle center-to-limb brightness variation on the star hardly plays a role in their discovery. Small planets, however, present scientists with immense challenges. Their effect on the stellar brightness is so small that it is extremely hard to distinguish from the natural brightness fluctuations of the star and from the noise that necessarily comes with any kind of observation. René Heller’s team has now been able to show that the sensitivity of the transit method can be significantly improved, if a more realistic light curve is assumed in the search algorithm. “Our new algorithm helps to draw a more realistic picture of the exoplanet population in space,” summarizes Michael Hippke of Sonneberg Observatory. “This method constitutes a significant step forward, especially in the search for Earth-like planets.”

This makes sense, but it must be understood that these are only candidate exoplanets, unconfirmed as yet. I would not be surprised if a majority are found to be false positives.

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More gravitational waves detected

9:47 am

Using the LIGO and Virgo gravitational wave telescopes astronomers have detected two more gravitational waves.

On April 25, 2019, one of the twin LIGO instruments and the Virgo detector observed a candidate signal which – if confirmed – would be the first binary neutron star merger during the third observation run, which began on April 1. A second candidate signal was seen on April 26, which – if confirmed – could be a never-observed-before collision of a neutron star with a black hole. The latter candidate was observed by both LIGO instruments and the Virgo detector. Dozens of telescopes on the Earth and in space are searching for electromagnetic or astro-particle counterparts. No identification with an electromagnetic transient signal nor a host galaxy has been made to date for either candidate.

The resolution of LIGO and VIRGO are somewhat limited, so other telescopes have to scan a very large part of the sky to spot a counterpart. It is therefore likely that it will be years before the first counterpart event is identified. When it is however it will tell us how far away the event was and confirm what kind of event it was. Right now, they are only making educated guesses.

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Lunar eclipse meteorite hit the Moon at almost 38,000 mph

10:33 am

By analyzing the data obtained of the meteorite impact that hit the Moon during the January 21 lunar eclipse, astronomers now estimate it crashed into the surface at almost 38,000 miles per hour and would have produced a crater about 50 feet across.

They also estimate that the meteorite itself had a mass of about 100 pounds with a diameter of between one to two feet.

The new crater itself has not yet been spotted, and probably can only be photographed with the high resolution camera on Lunar Reconnaissance Orbiter (LRO). I expect the LRO science team has already scheduled observations for this location. It will be interesting to see if the actual crater corresponds to the estimates of these astronomers.

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A stellar interloper in the Milky Way?

10:16 am

The uncertainty of science: Astronomers have identified a star inside the Milky Way whose chemical compositions suggests it was formed and originally came from a nearby dwarf galaxy.

This is the first discovery of a star having such extreme abundance ratios among Milky Way stars. On the other hand, several examples of stars having similar abundance ratios are known in dwarf galaxies. This result suggests that this star has formed in a dwarf galaxy, and has accreted onto the Milky Way in the process of galaxy formation. The abundance ratios of this star provide the clearest signature of merger events of dwarf galaxies in stellar chemical abundances known to date.

Though presently unique, this star probably is not the only such interloper in the Milky Way. It is believed by astronomers that our galaxy has absorbed a number of dwarf galaxies as it formed and grew, so we should expect more such stars to be discovered with time.

At the same time, we also must exercise some skepticism. Our understanding of galaxy formation is very preliminary, and thus the astronomers might be assuming too much about the chemical composition of dwarf galaxies in coming to this conclusion.

Posted at Los Angeles Airport on my way to Cannon Beach, Oregon, for a short vacation with friends.

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New Hubble data baffles cosmologists about universe’s expansion rate

10:15 am

The uncertainty of science: New and very firm data from the Hubble Space Telescope on the universe’s expansion rate conflicts with just-as-firm data obtained by Europe’s Planck astronomical probe.

According to Planck, the present universe should be expanding at a rate of 67 kilometers per second per megaparsec. According to Hubble, the actual expansion rate is 74 kilometers per second per megaparsec.

And according to the scientists involved, both data sets are reliable and trustworthy, leaving them baffled at the difference.

“This is not just two experiments disagreeing,” explained [lead researcher and Nobel laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University, in Baltimore, Maryland.] “We are measuring something fundamentally different. One is a measurement of how fast the universe is expanding today, as we see it. The other is a prediction based on the physics of the early universe and on measurements of how fast it ought to be expanding. If these values don’t agree, there becomes a very strong likelihood that we’re missing something in the cosmological model that connects the two eras.”

Ya think? Any cosmologist who claims we really understand what is going on, based on our present fragile and very limited knowledge, is either fooling him or herself or is trying to fool us.

I should note that there seems to be an effort, based on the press release above as well as this second one, to downplay the amount of uncertainties that exist in this cosmological work. Both releases fail to note that when scientists announced their first expansion rate estimate from Hubble’s first data back in 1995, those scientists claimed with absolute certainty that the expansion rate was 80 kilometers per second per megaparsec. At the time some scientists, led by the late Allan Sandage of the Carnegie Observatory, disputed this high number, claiming the number could be as low as 50. Some even said it could be as low as 30 kilometers. Sandage especially found himself poo-pooed by the cosmological community for disputing that the 80 number pushed by Hubble’s scientists in 1995.

In the end, the Hubble scientists in 1995 were closer to today’s Hubble number than Sandage, but his estimate was not wrong by that much more, and he was right when he said the number had to be lower. Either way, Hubble’s modern estimate of 74 for the present expansion rate is very well constrained, and is a far more trustworthy number than previous estimates.

However, do we know with any reliability what the expansion rate was billions of years ago? No. Cosmologists think it was faster, based on supernovae data, which is where the theory of dark energy comes from. It is also where Planck’s predictions come from.

That early expansion rate, however, is based on such tentative data, containing so many assumptions and such large margins of error, that no serious scientist should take it too seriously. It suggests things, but it certainly doesn’t confirm them.

This is why their faith in the numbers derived from Planck puzzles me. It is based on a “prediction,” as Riess admits in the quote above, which means it is based on a theoretical model. It is also based on that very tentative early supernovae data, which makes it very suspect to me.

The Hubble data is real data, obtained by looking at nearby stars in a very precise matter. Its margin of error is very small. It contains only a few assumptions, mostly involving our understanding of the Cepheid variable stars that Hubble observed. While skepticism is always called for, trusting this new Hubble data more is perfectly reasonable.

In the end, to really solve this conflict will require better data from the early universe. Unfortunately, that is not something that will be easy to get.

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Hubble celebrates 29 years in orbit

10:01 am

Hubble's 29th anniversary image

Click for full image.

In celebration of the 29th anniversary of the launch of the Hubble Space Telescope, the Space Telescope Science Institute (STScI) that operates the telescope has released a new image of one of the more spectacular astronomical objects in the southern hemisphere, what astronomers have dubbed the Southern Crab Nebula. I have cropped and reduced the image slightly to post it to the right.

The nebula, officially known as Hen 2-104, is located several thousand light-years from Earth in the southern hemisphere constellation of Centaurus. It appears to have two nested hourglass-shaped structures that were sculpted by a whirling pair of stars in a binary system. The duo consists of an aging red giant star and a burned-out star, a white dwarf. The red giant is shedding its outer layers. Some of this ejected material is attracted by the gravity of the companion white dwarf.

The result is that both stars are embedded in a flat disk of gas stretching between them. This belt of material constricts the outflow of gas so that it only speeds away above and below the disk. The result is an hourglass-shaped nebula.

The bubbles of gas and dust appear brightest at the edges, giving the illusion of crab leg structures. These “legs” are likely to be the places where the outflow slams into surrounding interstellar gas and dust, or possibly material which was earlier lost by the red giant star.

The outflow may only last a few thousand years, a tiny fraction of the lifetime of the system. This means that the outer structure may be just thousands of years old, but the inner hourglass must be a more recent outflow event. The red giant will ultimately collapse to become a white dwarf. After that, the surviving pair of white dwarfs will illuminate a shell of gas called a planetary nebula.

Hubble first revealed this nebula’s shape in a photograph taken in 1999.

The telescope was initially designed for a fifteen year mission. It is about to double that, assuming its last remaining gyroscopes can hold on through next year.

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Five exoplanets discovered with orbits from 15 to 40 years long

9:30 am

Twenty years of observations have now resulted in the discovery of five exoplanets with long solar orbits ranging from 15 to 40 years.

“As early as 1998, a planetary monitoring programme was set up and carried out scrupulously by the many … observers [using the EULER telescope belonging to Geneva University, Switzerland,] who took turns every two weeks in La Silla [Chile] for 20 years”, says Emily Rickman. The result is remarkable: five new planets have been discovered and the orbits of four others known have been precisely defined. All these planets have periods of revolution between 15.6 and 40.4 years, with masses ranging approximately from 3 to 27 times that of Jupiter. This study contributes to increasing the list of 26 planets with a rotation period greater than 15 years.

The press release is very poorly written. It does not explain how 21 years of observations pinpointed the orbit of an exoplanet of forty years. I suspect they have seen enough of the star’s wobble to extrapolate that orbit, but the press release should have explained this.

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Did an interstellar meteor hit the Earth in 2014?

5:55 am

By analyzing the speed in which it traveled through the atmosphere, astronomers propose that a meteor that hit the ground in 2014 was probably an interstellar object.

The scientists analyzed the Center for Near-Earth Object Studies’ catalog of meteor events detected by U.S. government sensors. They focused on the fastest meteors, because a high speed suggests a meteor is potentially not gravitationally bound to the sun and thus may originate from outside the solar system.

The researchers identified a meteor about 3 feet (0.9 meters) wide that was detected on Jan. 8, 2014, at an altitude of 11.6 miles (18.7 kilometers) over a point near Papua New Guinea’s Manus Island in the South Pacific. Its high speed of about 134,200 mph (216,000 km/h) and its trajectory suggested it came from outside the solar system, the scientists said. “We can use the atmosphere of the Earth as the detector for these meteors, which are too small to otherwise see,” Loeb told Space.com.

The meteor’s velocity suggested it received a gravitational boost during its journey, perhaps from the deep interior of a planetary system, or a star in the thick disk of the Milky Way.

To put it mildly, there are a lot of uncertainties about this conclusion. Nonetheless, their approach and hypothesis is very intriguing, and seems logical.

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Tess finds Earth-sized planet?

9:24 am

Scientists using the space telescope TESS think they may have found its first Earth-sized planet.

Its host star has about 80 percent of the mass of our Sun and is found about 53 light-years distant from Earth. HD 21749b has about 23 times Earth’s mass and a radius of about 2.7 times Earth’s. Its density indicates the planet has substantial atmosphere but is not rocky, so it could potentially help astronomers understand the composition and evolution of cooler sub-Neptune planet atmospheres.

Excitingly, the longer period sub-Neptune planet in this system is not alone. It has a sibling planet, HD 21749c, which takes about eight days to orbit the host star and is much smaller—similar in size to Earth. “Measuring the exact mass and composition of such a small planet will be challenging, but important for comparing HD 21749c to Earth,” said Wang. “Carnegie’s PFS team is continuing to collect data on this object with this goal in mind.”

In other words, they know almost nothing yet about the smaller exoplanet. They think it is similar in size to the Earth, but they don’t know its mass or composition.

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Astronomers take highest resolution radio image of black hole

9:54 am

shadow of black hole

Using a network of ground-based radio telescopes astronomers today released the highest resolution radio image of black hole ever produced.

Before giving more details, I must correct every other news report, as well as all of the press releases about this image. It is not “The first image of a black hole!” as these releases are claiming breathlessly. Radio telescope arrays have taken such images in the past, but their resolution was poor, so the result was not very imagelike. Instead, it showed contour lines in a coarse manner. Moreover, the coarseness of the resolution prevented them from seeing the black hole’s shadow itself.

This image now produced has the highest resolution ever for such a radio image, but believe me, it is still coarse. Nonetheless, it represents a giant technological leap forward. The effort required upgrades to many of these telescopes, along with significantly improved computer analysis. Now for some details:

Black holes are extraordinary cosmic objects with enormous masses but extremely compact sizes. The presence of these objects affects their environment in extreme ways, warping spacetime and super-heating any surrounding material. “If immersed in a bright region, like a disc of glowing gas, we expect a black hole to create a dark region similar to a shadow — something predicted by Einstein’s general relativity that we’ve never seen before,” explained chair of the EHT Science Council Heino Falcke of Radboud University, the Netherlands. “This shadow, caused by the gravitational bending and capture of light by the event horizon, reveals a lot about the nature of these fascinating objects and allowed us to measure the enormous mass of M87’s black hole.”

The image reveals the black hole at the center of Messier 87, a massive galaxy in the nearby Virgo galaxy cluster. This black hole resides 55 million light-years from Earth and has a mass 6.5-billion times that of the Sun.

…Multiple calibration and imaging methods have revealed a ring-like structure with a dark central region — the black hole’s shadow — that persisted over multiple independent EHT observations. “Once we were sure we had imaged the shadow, we could compare our observations to extensive computer models that include the physics of warped space, superheated matter and strong magnetic fields. Many of the features of the observed image match our theoretical understanding surprisingly well,” remarks Paul T.P. Ho, EHT Board member and Director of the East Asian Observatory. “This makes us confident about the interpretation of our observations, including our estimation of the black hole’s mass.” [emphasis mine]

Note the highlighted words. To create this image they needed to combine data from numerous radio telescopes. Such work requires extensive calibration. The resulting image is manufactured, though without doubt it is manufactured from real radio data accumulated by multiple telescopes. Because those telescopes are separated by distance, however, there will always be gaps between their images, and it is in the calibration and imaging methods that the gaps are extrapolated away.

I don’t wish to imply that this image is fake. It is not. That the features persisted over multiple observations confirms that they were actually seeing the black hole’s shadow. It also confirms that these new interferometry techniques work.

However, much of the press hyperbole today is an effort to justify the many millions in tax dollars spent on this effort. The effort was absolutely worthwhile scientifically, but government bureaucracies always feel a need to oversell their work. That is partly what is happening here.

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Fragment of a long dead planet’s iron core found orbiting white dwarf

8:25 am

Astronomers have identified the fragment of a long dead planet’s iron core orbiting a white dwarf star 410 light years away.

The [data] suggested its source was a solid object some 600 kilometers across—a suspected planetary core, with a density between 7.7 and 39 grams per cubic meter, comparable to the pure iron found within Earth’s core. “The density of the piece of rock is consistent with what we think the cores of planets [are],” says Luca Fossati of the Austrian Academy of Sciences, who was not involved in the paper.

It orbits the star every two hours, the fastest exoplanet orbit yet found. This alone should rip it apart, providing further evidence that the object’s density is very high.

The astronomers theorize that this object is likely the remains of a planet that existed when this star was young, and was destroyed as the star aged to become a red giant, expanding to swallow it. Later, when the star collapsed to become a tiny white dwarf, the core remained, its density allowing it survive as the planet’s outer crust was torn away.

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Telescope store sues Asian telescope manufacturers for fixing prices

11:21 am

A San Francisco store that sells telescopes to the public is suing two Asian telescope manufacturers — who make almost all recreational telescopes sold in the U.S. — for conspiring together to fix prices and create that monopoly.

Orion Telescopes and Binoculars, which is headquartered in Watsonville and has stores there and in Cupertino, is seeking more than $180 million in damages in a lawsuit. A federal court in Northern California said the complaint against telescope maker Ningbo Sunny, filed in 2016, can go to trial. A subsidiary of Ningbo Sunny, a Chinese company, bought Irvine telescope maker Meade Instruments in 2013.

In the complaint, Orion alleges that Ningbo Sunny and a Taiwanese telescope manufacturer, Synta Technology, shared confidential information that competitors normally would not share, including product pricing, order forecasts and credit arrangements.

My question is this: Why are no American telescope manufacturers competing in this market? Are our labor costs too high? Our government regulations too restrictive? A little bit of competition could easily end this collusion by these Asian manufacturers, assuming it is happening.

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Hubble’s main camera resumes science work

8:41 am

The main camera on the Hubble Space Telescope has resumed science operations after going into safe mode last week.

At 8:31 p.m. EST on Feb. 28, the Advanced Camera for Surveys aboard NASA’s Hubble Space Telescope suspended operations after an error was detected as the instrument was performing a routine boot procedure. The error indicated that software inside the camera had not loaded correctly in a small section of computer memory. The Hubble operations team ran repeated tests to reload the memory and check the entire process. No errors have been detected since the initial incident, and it appears that all circuits, computer memory and processors that are part of that boot process are now operating normally. The instrument has now been brought back to its standard operating mode for normal operations.

From the press release, it appears that they have not been able to trace why the error occurred. However, much like a typical Windows computer, after a mysterious crash and reboot now all appears well, so they have shrugged their shoulders and moved on.

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New analysis suggests photon could make dark matter unnecessary

1:28 pm

The uncertainty of science: A new analysis by physicists that assumes a very very low mass for the photon, the particle that transmits light, could very well explain the motions of stars in galaxies and make dark matter unnecessary.

Professor Dmitri Ryutov, who recently retired from the Lawrence Livermore National Laboratory in California, USA, is an expert in plasma physics. He was awarded the American Physical Society’s (APS) 2017 Maxwell Prize for Plasma Physics for his achievements in the field. Physicists generally credit Ryutov with establishing the upper limit for the mass of the photon. As this mass, even if it is nonzero, is extremely small, it is usually ignored when analyzing atomic and nuclear processes. But even a vanishingly tiny mass of the photon could, according to the scientists’ collaborative proposal, have an effect on large-scale astrophysical phenomena.

While visiting Johannes Gutenberg University Mainz (JGU), Ryutov, his host Professor Dmitry Budker of the Helmholtz Institute Mainz (HIM), and Professor Victor Flambaum, Fellow of the Gutenberg Research College of Mainz University, decided to take a closer look at the idea. They were interested in how the infinitesimally small mass of the photon could have an effect on massive galaxies. The mechanism at the core of the physicists’ assumption is a consequence of what is known as Maxwell-Proca equations. These would allow additional centripetal forces to be generated as a result of the electromagnetic stresses in a galaxy.

Are the effects as strong as those exerted by dark matter?

“The hypothetical effect we are investigating is not the result of increased gravity,” explained Dmitry Budker. This effect may occur concurrently with the assumed influence of dark matter. It may even – under certain circumstances – completely eliminate the need to evoke dark matter as a factor when it comes to explaining rotation curves. Rotation curves express the relationship between the orbital speeds of stars in a galaxy and their radial distance from the galaxy’s center. “By assuming a certain photon mass, much smaller than the current upper limit, we can show that this mass would be sufficient to generate additional forces in a galaxy and that these forces would be roughly large enough to explain the rotation curves,” said Budker. “This conclusion is extremely exciting.” [emphasis mine]

They readily admit that this first analysis is very preliminary, and causes some additional theoretical problems that conflict with known data. Nonetheless, this simple idea could eliminate the need for the additional dark matter particle that physicists have had trouble explaining or even finding.

In fact, I am somewhat baffled why physicists had not proposed this decades ago. It provides a much more straightforward explanation for the higher rotational curves in the outer parts of galaxies, and does not require any new physics.

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Hubble’s main camera down

1:36 pm

The main camera on the Hubble Space Telescope has suspended operations, and remains so as engineers troubleshoot the problem.

According to NASA, at 8:31 p.m. EST Feb. 28 (01:31 GMT March 1), 2019, the Advanced Camera for Surveys, or ACS, suspended its operations when an error was detected while the instrument was performing a routine boot procedure. “The error indicated that software inside the camera had not loaded correctly,” a statement from NASA reads. “A team of instrument system engineers, flight software experts and flight operations personnel quickly organized to download and analyze instrument diagnostic information.

They have not yet pinpointed the cause of the problem. The telescope has other cameras, however, though one of which had problems several months ago.

It is ten years since the last shuttle repair mission. That mission was expected to extend the telescope’s life for five years. Thus, the end Hubble’s life is getting closer and closer.

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Scientists confirm first exoplanet candidate found by Kepler

1:07 pm

Worlds without end: Ten years after Kepler was launched into space to find exoplanets, astronomers have finally confirmed one of the space telescopes thousands of candidates.

Despite being the very first planet candidate discovered by NASA’s Kepler Space Telescope, the object now known as Kepler-1658 b had a rocky road to confirmation. The initial estimate of the size of the planet’s host star was incorrect, so the sizes of both the star and Kepler-1658 b were vastly underestimated. It was later set aside as a false positive when the numbers didn’t quite make sense for the effects seen on its star for a body of that size. Fortuitously, Chontos’ first year graduate research project, which focused on re-analyzing Kepler host stars, happened at just the right time.

“Our new analysis, which uses stellar sound waves observed in the Kepler data to characterize the host star, demonstrated that the star is in fact three times larger than previously thought. This in turn means that the planet is three times larger, revealing that Kepler-1658 b is actually a hot Jupiter-like planet,” said Chontos. With this refined analysis, everything pointed to the object truly being a planet, but confirmation from new observations was still needed.

“We alerted Dave Latham (a senior astronomer at the Smithsonian Astrophysical Observatory, and co-author on the paper) and his team collected the necessary spectroscopic data to unambiguously show that Kepler-1658 b is a planet,” said Dan Huber, co-author and astronomer at the University of Hawaiʻi. “As one of the pioneers of exoplanet science and a key figure behind the Kepler mission, it was particularly fitting to have Dave be part of this confirmation.”

It is important to remember that until scientists obtain independent data on each of these candidates, they are not yet confirmed as exoplanets, and might only be false positives. To do this, however, is going to take a lot of work and time.

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