Tag: astronomy

New data from Tabby’s Star suggests that dust, not alien megastructures, is the cause of its dimming

8:39 am

New observations of Tabby’s Star now suggests that it is dust, not alien megastructures, that has caused the star’s erratic fluctuations in dimming over the past century.

“Dust is most likely the reason why the star’s light appears to dim and brighten. The new data shows that different colors of light are being blocked at different intensities. Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure,” said [LSU Department of Physics & Astronomy Assistant Professor Tabetha Boyajian].

Though the data appears strong, it still leaves astronomers a bit baffled about how dust could cause the particular dimming they have seen.

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Arecibo returns to operation with images of asteroid Phaethon

10:02 am

The Arecibo Observatory in Puerto Rico has resumed science observations after recovering from Hurricane Maria with new radio images of the asteroid Phaethon.

After several months of downtime after Hurricane Maria blew through, the Arecibo Observatory Planetary Radar has returned to normal operation, providing the highest-resolution images to date of near-Earth asteroid 3200 Phaethon during its Dec. 16 flyby of Earth. The radar images, which are subtle at the available resolution, reveal the asteroid is spheroidal in shape and has a large concavity at least several hundred meters in extent near the leading edge, and a conspicuous dark, circular feature near one of the poles. Arecibo’s radar images of Phaethon have resolutions as fine as about 250 feet (75 meters) per pixel.

The images also revealed that Phaethon, which is considered a potentially hazardous near Earth asteroid, is about 3.6 miles across and is about a half mile larger than previously believed.

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A star that is devouring its planets?

12:55 pm

Astronomers now think that a nearby star that erratically dims inexplicably does so because of clouds of debris left by the destruction of one or more exoplanets.

A team of U.S. astronomers studying the star RZ Piscium has found evidence suggesting its strange, unpredictable dimming episodes may be caused by vast orbiting clouds of gas and dust, the remains of one or more destroyed planets. “Our observations show there are massive blobs of dust and gas that occasionally block the star’s light and are probably spiraling into it,” said Kristina Punzi, a doctoral student at the Rochester Institute of Technology (RIT) in New York and lead author of a paper describing the findings. “Although there could be other explanations, we suggest this material may have been produced by the break-up of massive orbiting bodies near the star.”

Their data also suggest that the star is young.

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The best infrared image yet of a star’s surface

10:34 am

The surface of a star

Astronomers, using the Very Large Telescope in Chile have taken the best infrared image of the surface of a star, revealing gigantic granules or convection cells, across the star’s surface. These cells are somewhat similar to the bubbles you see when you simmer tomato sauce. Our own Sun usually has about two million such cells across its surface. For this aging red giant, which has the same mass as the Sun but has expanded to 350 times its diameter, things are different.

[The astronomers] found that the surface of this red giant has just a few convective cells, or granules, that are each about 120 million kilometres across — about a quarter of the star’s diameter [2]. Just one of these granules would extend from the Sun to beyond Venus.

I have posted the image on the right, reduced slightly in resolution to show here. The press release says that this is the first time that such granules have been imaged, but I think that is a bit of an overstatement. In fact, one of the very first articles I ever wrote, back in 1994, described an infrared image taken of Betelgeuse that showed similar giant bubbles or cells. What makes this image significant is its improved resolution. The ability to see smaller details on the faces of distant stars continues to improve.

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Oumuamua has a thick carbon crust built up by its interstellar travel

8:59 am

New results of observations of the interstellar object Oumuamua suggest that it has a thick crust of organic carbon soot that was slowly built up during the millions of years it traveled between the stars.

New observations of the cigar-shaped body found evidence for a deep surface layer that formed when organic ices – such as frozen carbon dioxide, methane and methanol – that make up the object were battered by the intense radiation that exists between the stars.

…The deep outer crust may have formed on the body over millions or even billions of years and gives ‘Oumuamua a dark red colour, according to researchers who investigated the object with the William Herschel Telescope on La Palma in the Canary Islands and the European Southern observatory in Chile’s Atacama desert.

There have been a slew of news stories today about these results, all focusing not on the crust of the object, which tells us nothing really about its interior, but on one quote by one scientist from the press release, who theorized — based on zero data — that the interior of the object could be icy. From this quote I have seen at least a half dozen stories exclaiming that Oumuamua thus could be like a comet, based on no information at all.

All we have learned is that traveling for a long time in interstellar space causes a build up of carbon-rich materials on the surface of an object. What might be hidden under that crust remains entirely unknown. It could be icy, but we don’t know that.

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Initial analysis of radio observations of Oumuamua detect no artificial signals

1:34 pm

The initial analysis of the first set of radio observations of Oumuamua by Breakthrough Listen has so far not detected any artificial signals.

No such signals have been detected, although the analysis is not yet complete. So far, data from the S-band receiver (covering frequencies from 1.7 to 2.6 GHz) has been processed, and analysis of the remaining three bands is ongoing. A subset of the S-band data is now available for public inspection in the Breakthrough Listen archive3, and additional data will be added as it becomes available.

The data is stored in specialized formats, and analyzing it may be challenging for non-experts. We invite those who are interested to study the tutorial material provided by the Breakthrough Listen science team at the University of California, Berkeley, SETI Research Center and to assist with the analysis not only of this intriguing object, but of the entire Breakthrough Listen dataset.

They still plan three more observation sessions.

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New exoplanet makes eight in rival solar system

1:27 pm

comparing solar systems

Worlds without end: Astronomers using Kepler data mined by computers have discovered an eighth planet in another solar system, making that system somewhat comparable to our own.

The newly discovered Kepler-90i — a sizzling hot, rocky planet orbiting its star once every 14.4 days — was found using computers that “learned” to find planets in data from NASA’s Kepler space telescope. Kepler finds distant planets beyond the solar system, or exoplanets, by detecting the minuscule change in brightness when a planet transits (crosses in front of) a star.

Vanderburg, a NASA Sagan fellow at UT Austin, and Shallue, a Google machine learning researcher, teamed up to train a computer to learn how to identify signs of an exoplanet in the light readings from distant stars recorded by Kepler. Similar to the way neurons connect in the human brain, this “neural network” sifted through the Kepler data to identify the weak transit signals from a previously missed eighth planet orbiting Kepler-90, a sun-like star 2,545 light-years from Earth in the constellation Draco. “For the first time since our solar system planets were discovered thousands of years ago, we know for sure that our solar system is not the sole record holder for the most planets,” Vanderburg said.

The image to the right compares the planet sizes between this solar system and ours. It does not show that, for this distant star, all eight planets have orbits closer to the star than the Earth, and would therefore be very unlikely to harbor life.

One more thing: This story is very cool, but it also is another one of those NASA press releases that the agency PR department overhyped beforehand, even allowing some reporters to think that it might involve the discovery of life beyond Earth. Not surprisingly, several news sources and radio shows asked me to talk about it. To their disappointment I said I’d rather wait, since NASA has overhyped more than a few stories like this in recent years. Once again, my instincts were right. This story has nothing to do with alien life, and though interesting, is actually not that big a deal.

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Breakthrough Listen to observe Ourmuamua

10:47 am

Breakthrough Listen, one of billionaire Yuri Milner’s Breakthrough initiatives, is going to do an observation campaign of the interstellar object Ourmuamua using the Green Bank Radio telescope.

It has a highly unusual structure for an asteroid – an elongated cigar shape, hundreds of meters in length but with width and height perhaps only one tenth as long.

Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimize friction and damage from interstellar gas and dust. While a natural origin is more likely, there is currently no consensus on what that origin might have been, and Breakthrough Listen is well positioned to explore the possibility that ‘Oumuamua could be an artifact.

Listen’s observation campaign will begin on Wednesday, December 13 at 3:00 pm ET. Using the Robert C. Byrd Green Bank Telescope, it will continue to observe ‘Oumuamua across four radio bands, from 1 to 12 GHz. Its first phase of observations will last a total of 10 hours, divided into four “epochs” based on the object’s period of rotation.

If anything, this observation will provide us more information about Ourmuamua itself, which unfortunately is very limited because the object was already on its way out when it was discovered.

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More delays expected for launch of Webb telescope

8:52 am

NASA’s chief scientist admitted during House hearings this week that there will possibly be further delays in the launch of the James Webb Space Telescope, now set for the 2nd quarter of 2019.

“At this moment in time, with the information that I have, I believe it’s achievable,” he said of the current launch window of March to June 2019, which NASA announced in September after delaying the launch from October 2018. However, he said an independent review “is exactly what we should be doing, and frankly I have directed the team to do just that in January.”

That review won’t start until January, he said, because of ongoing tests of unfolding the sunshade of the space telescope. Previous tests, he said, took much longer than anticipated, playing a key factor in the decision to delay the launch. An updated launch date, he said, would likely come in “January or February.”

Such an independent review was proposed earlier in the hearing by another witness, retired aerospace executive Thomas Young. “In my opinion, the launch date and required funding cannot be determined until a new plan is thoroughly developed and verified by independent review,” he said.

While it does make perfect sense to make sure everything is really really really ready before launch, that this telescope is already 8 years behind schedule and yet might still need more delays suggests that the whole project was managed badly, from start to finish.

The hearing also dealt with the cost increases NASA is experiencing for WFIRST. As is usual, it sounds like NASA’s buy-in approach there has worked, and that Congress will fork up the extra cash to keep that project alive, until it experiences further delays and more cost increases, when Congress will fork up even more money. Then, wash and repeat. The WFIRST budget is already up from about $3.5 billion to more than $4 billion. I predict before it is done it will have cost around $8-$10 billion, and not launch until the late 2020s, at the earliest.

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The fly-by anomaly returns with Juno

9:48 pm

The uncertainty of science: An orbital discrepancy between where engineers predict where Juno should be and where it actually is suggests it represents the recurrence of an anomaly that has been seen with numerous past planetary spacecraft.

During the 1970s when the Pioneer 10 and 11 probes were launched, visiting Jupiter and Saturn before heading off towards the edge of the Solar System, these probes both experienced something strange as they passed between 20 to 70 AU (Uranus to the Kuiper Belt) from the Sun.

Basically, the probes were both 386,000 km (240,000 mi) farther from where existing models predicted they would be. This came to be known as the “Pioneer anomaly“, which became common lore within the space physics community. While the Pioneer anomaly was resolved, the same phenomena has occurred many times since then with subsequent missions.

…Another mystery is that while in some cases the anomaly was clear, in others it was on the threshold of detectability or simply absent – as was the case with Juno‘s flyby of Earth in October of 2013. The absence of any convincing explanation has led to a number of explanations, ranging from the influence or dark matter and tidal effects to extensions of General Relativity and the existence of new physics.

However, none of these have produced a substantive explanation that could account for flyby anomalies.

The article describes in detail an effort to pin down the extent of Juno’s orbital anomaly, and to use that information to develop a model that would explain the phenomenon. Not surprisingly, they have not really come up with a comprehensive explanation. To me, the variability of the phenomenon suggests that it isn’t real, that it is either an unmeasured instrument effect or an ordinary component of solar system travel and orbital mechanics that programmers have not yet pinned down. For example, the gravitational effect of every planet and rock in the solar system will influence the path of a spacecraft, though with most that influence will be very small. It would not surprise me if this anomaly is simply the consequence of missing some of this influence.

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Baby stars at center of galaxy

2:40 pm

New observations of the region surrounding Sagittarius A* (Sgr A*), the super-massive black hole at the center of the Milky Way, has confirmed earlier research by finding what appears to be eleven newly formed baby stars.

Prior observations of the region surrounding Sgr A* by Zadeh and his team had revealed multiple massive infant stars but the finding was not conclusive. These objects, known as proplyds, are common features in more placid star-forming regions, like the Orion Nebula. The new measurements provide more conclusive evidence for young star formation activity. Though the galactic center is a challenging environment for star formation, it is possible for particularly dense cores of hydrogen gas to cross the necessary threshold and forge new stars.

The new ALMA observations, however, revealed something even more remarkable, signs that 11 low-mass protostars are forming within one parsec – a scant three light-years – of the galaxy’s central black hole. Zadeh and his team used ALMA to confirm that the masses and momentum transfer rates – the ability of the protostar jets to plow through surrounding interstellar material – are consistent with young protostars found throughout the disk of our galaxy. “This discovery provides evidence that star formation is taking place within clouds surprisingly close to Sagittarius A*,” said Al Wootten with the National Radio Astronomy Observatory in Charlottesville, Virginia, and co-author on the paper.

They have several theories on how new stars could coalesce in such a violent and turbulent region, but none appears that convincing. Essentially, this is a mystery that does not yet have an answer. It does tell us however that star formation can occur almost anywhere.

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The organic dust of Comet 67P/C-G

11:36 am

A study of the dust released by Comet 67P/C-G and captured by Rosetta shows that carbon molecules appear to comprise the comet’s largest component, and that this material is found in the form of very large macromolecules.

As the study shows, organic molecules are among those ingredients at the top of the list. These account for about 45 percent of the weight of the solid cometary material. “Rosetta’s comet thus belongs to the most carbon-rich bodies we know in the solar system,” says MPS scientist and COSIMA team member Dr. Oliver Stenzel. The other part of the total weight, about 55 percent, is provided by mineral substances, mainly silicates. It is striking that they are almost exclusively non-hydrated minerals i.e. missing water compounds. “Of course, Rosetta’s comet contains water like any other comet, too,” says Hilchenbach. “But because comets have spent most of their time at the icy rim of the solar system, it has almost always been frozen and could not react with the minerals.” The researchers therefore regard the lack of hydrated minerals in the comet’s dust as an indication that 67P contains very pristine material.

…The current findings also touch on our ideas of how life on Earth came about. In a previous publication, the COSIMA team was able to show that the carbon found in Rosetta’s comet is mainly in the form of large, organic macromolecules. Together with the current study, it becomes clear that these compounds make up a large part of the cometary material. Thus, if comets indeed supplied the early Earth with organic matter, as many researchers assume, it would probably have been mainly in the form of such macromolecules.

Organic here does not mean life, but is instead used as chemists use it, to mean the molecule includes the element carbon. The results do suggest however that the early solar system had a lot of carbon available, and that much of it was in a relatively pure form available to interact with other elements.

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Chinese space probe detects possible dark matter signal

8:56 am

The uncertainty of science: A Chinese space probe designed to measure cosmic rays has detected a pattern that could be evidence of the existence of dark matter.

Researchers launched the spacecraft from the Jiuquan Satellite Launch Center in the Gobi Desert, about 1600 kilometers west of Beijing, in December 2015. Its primary instrument—a stack of thin, crisscrossed detector strips—is tuned to observe the incoming direction, energy, and electric charge of the particles that make up cosmic rays, particularly electrons and positrons, the antimatter counterparts of electrons. Cosmic rays emanate from conventional astrophysical objects, like exploding supernovae in the galaxy. But if dark matter consists of WIMPs, these would occasionally annihilate each other and create electron-positron pairs, which might be detected as an excess over the expected abundance of particles from conventional objects.

In its first 530 days of scientific observations, DAMPE detected 1.5 million cosmic ray electrons and positrons above a certain energy threshold. When researchers plot of the number of particles against their energy, they’d expect to see a smooth curve. But previous experiments have hinted at an anomalous break in the curve. Now, DAMPE has confirmed that deviation. “It may be evidence of dark matter,” but the break in the curve “may be from some other cosmic ray source,” says astrophysicist Chang Jin, who leads the collaboration at the Chinese Academy of Science’s (CAS’s) Purple Mountain Observatory (PMO) in Nanjing. [emphasis mine]

I must emphasize the large uncertainty here. They have not detected dark matter. Not even close. What they have detected is a pattern in how the spacecraft is detecting cosmic rays that was predicted by the existence of dark matter. That pattern however could have other causes, and the consistent failure of other efforts to directly find dark matter strengthens the possibility that this break is caused by those other causes.

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New report says WFIRST is “not executable”

11:05 pm

Another Webb! New NASA report has declared the agency’s next big telescope following the James Webb Space Telescope, dubbed the Wide Field Infrared Survey Telescope (WFIRST) is “not executable” and is significantly over budget.

“The risks to the primary mission of WFIRST are significant and therefore the mission is not executable without adjustments and/or additional resources,” the report states. It estimated the cost of the project at $3.9 billion to $4.2 billion, significantly above the project’s $3.6 billion budget.

Produced by an independent and external team to review the technical aspects of the program, its management, and costs, the report is critical of a series of key decisions made by NASA. The addition of a coronagraph and other design choices have made for a telescope that is “more complex than probably anticipated” and have substantially increased risks and costs, according to the report.

It also offered a scathing review of the relationship between NASA headquarters and the telescope’s program managers at Goddard Space Flight Center. “The NASA HQ-to-Program governance structure is dysfunctional and should be corrected for clarity in roles, accountability, and authority,” the report states.

Did you ever get a feeling of deja-vu? This is the same story that we saw with Hubble, and with Webb. It’s called a buy-in. The agency purposely sets the budget too low to begin with, gets it started, which then forces Congress to pay the big bucks when the budget inevitably goes out of control.

From my perspective I think this is the time to shut the project down. Since Hubble astronomers have apparently begun to take NASA’s cash cow for granted, and need to relearn the lesson that they don’t have a guarantee on the treasury. Once they get over the shock of losing WFIRST, they might then start proposing good space telescopes that are affordable and can be built relatively quickly, instead of these boondoggles that take forever and ten times the initial budget to build.

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Arecibo gets a backer to keep it running

10:59 pm

The National Science Foundation has found at least one backer to pick up the majority of the cost for running the Arecibo Observatory in Puerto Rico, thus keeping it operational.

For about a decade, the National Science Foundation, which owns the observatory and supplies about two-thirds of its $12 million budget, had been mulling downsizing or even shuttering the telescope to free up funds for other projects. Instead, the NSF will continue scientific operations at the facility in collaboration with an unnamed partner organization, according to a Record of Decision signed this week.

Arecibo sustained $4 million to $8 million in damage during the hurricane, according James Ulvestad, acting assistant director for the agency’s mathematical and physical sciences directorate. Some scientists worried that would weaken the case for keeping the observatory operational.

But Ulvestad said the agency’s Record of Decision reflects that it has received viable partnership proposals from one or more collaborators — though he would not provide details about those proposals. This announcement allows the NSF to move forward with negotiations on a new management contract.

Under the new plan, the agency will reduce its annual contribution to the observatory from about $8.2 million to $2 million over the next five years. It is also committed to funding any repairs required to restore Arecibo to its pre-hurricane condition, Ulvestad said.

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Another LIGO black hole merger detected

8:47 am

Astronomers have announced another black hole merger detected by the LIGO gravitational wave observatory.

Dubbed GW170608, the latest discovery was produced by the merger of two relatively light black holes, 7 and 12 times the mass of the sun, at a distance of about a billion light-years from Earth. The merger left behind a final black hole 18 times the mass of the sun, meaning that energy equivalent to about 1 solar mass was emitted as gravitational waves during the collision.

This event, detected by the two NSF-supported LIGO detectors at 02:01:16 UTC on June 8, 2017 (or 10:01:16 pm on June 7 in US Eastern Daylight time), was actually the second binary black hole merger observed during LIGO’s second observation run since being upgraded in a program called Advanced LIGO. But its announcement was delayed due to the time required to understand two other discoveries: a LIGO-Virgo three-detector observation of gravitational waves from another binary black hole merger (GW170814) on August 14, and the first-ever detection of a binary neutron star merger (GW170817) in light and gravitational waves on August 17.

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Interstellar object resembles asteroid

6:43 pm

Astronomers who have been observing the interstellar object that zipped past the Sun last month have concluded that it mostly resembles asteroids seen in our own solar system.

From its changing brightness, the team inferred that U1 is highly elongated with rough dimensions 30m x 30m x 180m. About twice the height of the Statue of Liberty, the 6:1 aspect ratio of U1 is “similar to the proportions of a fire extinguisher — although U1 is not as red as that,” says David Jewitt (UCLA), the first author of the study.

“With such an elongated shape, U1 probably needs a little cohesive strength to hold it together. But that’s not really unusual,” remarked study coauthor Jayadev Rajagopal (National Optical Astronomy Observatory). Commenting on its size, rotation, and color, Rajagopal mused that, “the most remarkable thing about U1 is that, except for its shape, how familiar and physically unremarkable it is.”

I wonder if they are still tracking it.

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Astronomers find habitable Earth-mass planet 11 light years away

9:15 am

Worlds without end: Astronomers have found an Earth-mass planet 11 light years away, orbiting a quiet red dwarf star in the habitable zone.

Unlike Proxima Centauri, which periodically has large flares which make its Earth-sized planet less hospitable to life, this red dwarf, Ross 128, is more stable.

Many red dwarf stars, including Proxima Centauri, are subject to flares that occasionally bathe their orbiting planets in deadly ultraviolet and X-ray radiation. However, it seems that Ross 128 is a much quieter star, and so its planets may be the closest known comfortable abode for possible life.

Although it is currently 11 light-years from Earth, Ross 128 is moving towards us and is expected to become our nearest stellar neighbour in just 79 000 years — a blink of the eye in cosmic terms. Ross 128 b will by then take the crown from Proxima b and become the closest exoplanet to Earth!

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Zwicky Transient Facility sees first light

10:54 am

Astronomers announced today that the Zwicky Transient Facility at the Palomar Observatory in California has seen first light, and will begin full operations in 2018.

When fully operational in 2018, the ZTF will scan almost the entire northern sky every night. Based at the Palomar Observatory in southern California and operated by Caltech, the ZTF’s goal is to use these nightly images to identify “transient” objects that vary between observations — identifying events ranging from supernovae millions of light years away to near-Earth asteroids.
an image of stars and the night sky

In 2016, the UW Department of Astronomy formally joined the ZTF team and will help develop new methods to identify the most “interesting” of the millions of changes in the sky — including new objects — that the ZTF will detect each night and alert scientists. That way, these high-priority transient objects can be followed up in detail by larger telescopes, including the UW’s share of the Apache Point Observatory 3.5-meter telescope.

By producing new high resolution images of the entire northern sky every night, this telescope instrument is going to discover gobs of new transients, from supernovae to binaries to novae to things we haven’t even seen before.

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Physicists once again fail to detect dark matter

9:25 am

The uncertainty of science: The most sensitive detector yet created by physicists has once again failed to detect dark matter, casting strong doubt on all present theories for its existence.

The latest results from an experiment called XENON1T at the Gran Sasso National Laboratory in Italy, published on 30 October, continue a dry spell stretching back 30 years in the quest to nab dark-matter particles. An attempt by a Chinese team to detect the elusive stuff, the results of which were published on the same day, also came up empty-handed. Ongoing attempts by space-based telescopes, as well as at CERN, the European particle-physics laboratory near Geneva, Switzerland, have also not spotted any hints of dark-matter particles.

The findings have left researchers struggling for answers. “We do not understand how the Universe works at a deeper and more profound level than most of us care to admit,” says Stacy McGaugh, an astrophysicist at Case Western Reserve University in Cleveland, Ohio.

The process here has been a good demonstration of the scientific method. Observers detect a phenomenon that does not make sense, which in this case was that the outer regions of galaxies rotate so fast that they should fly apart. Theorists then come up with a hypothesis to explain the phenomenon, which here was dark matter, subatomic particles that have weight but do not generally interact with the rest of the universe except by their mass, which acts to hold the galaxies together. Observers than try to prove the hypothesis by finding these theorized particles.

When the particles are not found, the theorists begin to rethink their theories. Maybe dark matter does not exist. Maybe (as is mentioned near the end of the article) a rethinking of the nature of gravity itself might be necessary. Or possibly the unseen matter is not subatomic, but ordinary matter not yet detected.

If only the climate field would apply this basic scientific method to its work. There, scientists found that carbon dioxide is increasing in the atmosphere. Some theorists posited an hypothesis that said that this increase might cause the climate to warm, and created numerous (almost a hundred) models to predict this warming. After more than thirty years, however, none of those models has successfully worked. The climate has not warmed as predicted, which suggests the hypothesis is flawed, and needs rethinking. Sadly, the leaders in the climate field refuse to do this rethinking. Instead, they appear willing to adjust and change their data to make it fit, sometimes in ways that are downright fraudulent.

This is not how science is done, and it is doing a terrible disservice to both science and society in general.

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First infrared image of a red giant star with a mass of the sun

8:48 am

W Hydrae

Astronomers have used the ALMA array in Chile to take the first infrared image of a red giant star that has a mass similar to the Sun.

The dotted ring in the the image, cropped to post here, shows the Earth’s orbit. The star is farther along in its evolution than the Sun, and has expanded as it begins to use up its nuclear fuel.

The observations have also surprised the scientists. The presence of an unexpectedly compact and bright spot provides evidence that the star has surprisingly hot gas in a layer above the star’s surface: a chromosphere. “Our measurements of the bright spot suggest there are powerful shock waves in the star’s atmosphere that reach higher temperatures than are predicted by current theoretical models for AGB stars,” says Theo Khouri, astronomer at Chalmers and member of the team.

An alternative possibility is at least as surprising: that the star was undergoing a giant flare when the observations were made.

The handful of infrared images that astronomers have taken so far of several red giant stars indicates that these stars no longer look like the Sun, with a clear and precise spherical shape, but are puffed up almost like a cloud, with many uneven layers and complex extensions produced by their chaotic nature. This image of W Hydrae reinforces this impression.

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Astronomers find Kuiper Belt-like ring around Proxima Centauri

3:32 pm

Worlds without end: Astronomers have found a dusty ring 1 to 4 astronomical units from the nearest star, Proxima Centauri.

Because Proxima Centauri is a smaller, dimmer star, its system is more compact. Proxima b [the star’s known exoplanet] circles the star at 0.05 astronomical units (a.u., the average distance between Earth and the Sun) — for reference, Mercury orbits the Sun at 0.39 a.u. The dusty ring lies well beyond that, extending from 1 to 4 a.u.

The Proxima ring is similar in some ways to the Kuiper Belt, a cold, dusty belt in the far reaches of our solar system (beyond 40 a.u.) that contains a fraction of Earth’s mass. While the Kuiper belt is well known for larger members such as Pluto and Eris, it also contains fine grains, ground down through collisions over billions of years. The dust ALMA observed around Proxima Centauri is composed of similar small grains. The average temperature and total mass of the Proxima ring is also about the same as our Kuiper Belt.

Because the ring here much closer to the star than our Kuiper Belt, the material is much more densely packed. Moreover, the presence of both a ring and an exoplanet suggests more planets might remain undiscovered there, increasing the chances that this star could have a solar system very worthwhile exploring.

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Fifth mirror for Giant Magellan Telescope has been cast

9:20 am

The fifth mirror, out of seven, for Giant Magellan Telescope (GMT) has been cast by the University of Arizona mirror lab.

With its casting this weekend, the fifth GMT mirror joins three additional GMT mirrors at various stages of production in the Mirror Lab. Polishing of mirror 2’s front surface is well underway; coarse grinding will begin on the front of the third mirror shortly and mirror number 4, the central mirror, will soon be ready for coarse grinding following mirror 3. The first GMT mirror was completed several years ago and was moved to a storage location in Tucson this September, awaiting the next stage of its journey to Chile. The glass for mirror 6 has been delivered to Tucson and mirror seven’s glass is on order from the Ohara factory in Japan.

In time, the giant mirrors will be transported to GMT’s future home in the Chilean Andes at the Carnegie Institution for Science’s Las Campanas Observatory. This site is known for being one of the best astronomical sites on the planet with its clear, dark skies and stable airflow producing exceptionally sharp images. GMTO has broken ground in Chile and has developed the infrastructure on the site needed to support construction activities.

If all goes right, GMT will begin its science work using 4 mirrors in 2020, with the use of all 7 mirrors beginning in 2022. This will be several years before the larger Thirty Meter Telescope and the European Extremely Large Telescope.

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NASA wants private company to take over Spitzer Space Telescope

6:00 pm

NASA has issued a request for proposals from private companies or organizations to take over the operation of the Spitzer Space Telescope after 2019.

NASA’s current plans call for operating Spitzer through March of 2019 to perform preparatory observations for the James Webb Space Telescope. That schedule was based on plans for a fall 2018 launch of JWST, which has since been delayed to the spring of 2019. Under that plan, NASA would close out the Spitzer mission by fiscal year 2020. That plan was intended to save NASA the cost of running Spitzer, which is currently $14 million a year. The spacecraft itself, though, remains in good condition and could operating well beyond NASA’s current plan.

“The observatory and the IRAC instrument are in excellent health. We don’t have really any issues with the hardware,” said Lisa Storrie-Lombardi, Spitzer project manager, in a presentation to the committee Oct. 18. IRAC is the Infrared Array Camera, an instrument that continues operations at its two shortest wavelengths long after the spacecraft exhausted the supply of liquid helium coolant.

The spacecraft’s only consumable is nitrogen gas used for the spacecraft’s thrusters, and Storrie-Lombardi said the spacecraft still had half its supply of nitrogen 14 years after launch.

The way a private organization could make money on this is to charge astronomers and research projects for observation time. This could work, since there is usually a greater demand for research time than available observatories.

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New exoplanet defies accepted theories of planet formation

8:48 am

The uncertainty of science: A newly discovered exoplanet, the size of Jupiter and orbiting a star half the size of the Sun, should not exist based on all the presently favored theories of planet formation.

New research, led by Dr Daniel Bayliss and Professor Peter Wheatley from the University of Warwick’s Astronomy and Astrophysics Group, has identified the unusual planet NGTS-1b – the largest planet compared to the size of its companion star ever discovered in the universe.

NGTS-1b is a gas giant six hundred light years away, the size of Jupiter, and orbits a small star with a radius and mass half that of our sun.

Its existence challenges theories of planet formation which state that a planet of this size could not be formed by such a small star. According to these theories, small stars can readily form rocky planets but do not gather enough material together to form Jupiter-sized planets. The planet is a hot Jupiter, at least as large as the Jupiter in our solar system, but with around 20% less mass. It is very close to its star – just 3% of the distance between Earth and the Sun – and orbits the star every 2.6 days, meaning a year on NGTS-1b lasts two and a half days.

No one should be surprised by this. While the present theories of planet formation are useful and necessary, giving scientists a rough framework for studying exoplanets, they should not be taken too seriously. We simply do not yet have enough information about how stars, solar systems, and planets form.

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Astronomers find 20 more exoplanet candidates in Kepler archive

8:30 am

Worlds without end: Astronomers reviewing the Kepler archive have found 20 more exoplanet candidates, including one that has a mass about 97 percent of the Earth with an orbit 395 days long circling a star like the Sun.

The planet would be colder than Earth, as its star is slightly cooler than the Sun, and its orbit is slightly farther away. Nonetheless, this is an amazing twin, and would certainly be a prime target when interstellar travel becomes routine.

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The first large object identified coming from interstellar space

6:38 pm

Astronomers think they have spotted the first large object to come from beyond the solar system.

Based on its apparent brightness, dynamicist Bill Gray calculates that it would have a diameter of about 160 meters (525 feet) if it were a rock with a surface reflectivity of 10%. “It went past the Sun really fast,” Gray notes, “and may not have had time to heat up enough to break apart.”

Now it’s headed out of the solar system, never to return. It passed closest to Earth on October 14th at a distance of about 24,000,000 km (15,000,000 miles), and astronomers worldwide have been tracking it in the hopes of divining its true nature — especially whether it’s displaying any cometary activity.

…According to Gray, Comet PanSTARRS appears to have entered the solar system from the direction of the constellation Lyra, within a couple of degrees of right ascension 18h 50m, declination +35° 13′. That’s tantalizingly close to Vega — and eerily reminiscent of the plot of the movie Contact — but its exact path doesn’t (yet) appear to link any particular star.

This object entered the solar system moving at 26 km (16 miles) per second. At that speed, in 10 million years it would traverse 8,200,000,000,000,000 km — more than 850 light-years.

Reminds me of a really good science fiction novel I read recently. They should keep an eye on it for as long as they can, just in case it suddenly changes course and settles into a more circular orbit around the Sun. In the unlikely case it does that, it might just be the biggest discovery in history.

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NASA instrument for European space telescope flawed and must be rebuilt

5:29 pm

The NASA instrument for Europe’s Euclid optical/near-infrared space telescope has been found defective and must be rebuilt, thus delaying the launch of the telescope by at least one year.

What interested me about this telescope is its goals and specifications:

Euclid is a two-ton space telescope selected by ESA in 2011 as a medium-class mission in its Cosmic Vision program of space science missions. The spacecraft features a 1.2-meter telescope with visible and near-infrared instruments to study dark energy and dark matter, which combined account for about 95 percent of the universe. Euclid will operate at the Earth-sun L-2 Lagrange point, 1.5 million kilometers from Earth, that is used by other infrared astronomy missions.

With a mirror about half the size of Hubble’s, this telescope will act as a partial replacement and back up for it. In fact, it will likely make numerous ground-breaking discoveries, as every optical telescope placed above the atmosphere has so far done.

Meanwhile, the article provided no information on the flaws, who built the flawed instrument, and who will pay for the delays its failure will cause.

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Astronomers reduce estimate of still undiscovered dangerous asteroids

11:49 am

Astronomers have now reduced [pdf] their estimate of the number of still undiscovered dangerous Near Earth Asteroids (NEAs) that could impact the Earth from 100 to less than 40.

Observers have been cataloging potentially hazardous asteroids for decades. Based on the number of finds, the area of sky explored, and the limiting brightness our telescopes and cameras can reach, researchers can estimate what fraction of the NEA population has been detected so far and how many more objects lurk undiscovered. Harris has published numerous such estimates over the years. Recently he realized that his estimates have been plagued by a seemingly innocuous but nonetheless consequential round-off error. Once corrected, the estimated number of large (diameter > 1 kilometer) NEAs remaining to be discovered decreases from more than 100 to less than 40.

To put it mildly, there is a lot of uncertainty here. This also reminds me of the cavers’ joke question: “How many miles of unexplored passages does this cave have?”

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