Tag: astronomy

How to blow up a star

8:29 am

Link here. The story details the new supercomputer simulation work attempting to model the internal processes inside a dying star that cause it to explode as a supernova.

For more than half a century, physicists have suspected that the heat produced by elusive particles called neutrinos, created in the core of a star, could generate a blast that radiates more energy in a single second than the Sun will in its lifetime. But they have had trouble proving that hypothesis. The detonation process is so complex — incorporating general relativity, fluid dynamics, nuclear and other physics — that computers have struggled to mimic the mechanism in silico. And that poses a problem. “If you can’t reproduce it,” Janka says, “that means you don’t understand it.”

Now, improvements in raw computing power, along with efforts to capture the stellar physics in acute detail, have enabled substantial progress. Janka’s simulation marked the first time that physicists had been able to get a realistic 3D model of the most common type of supernova to explode. Just months later, a competing group based at Oak Ridge National Laboratory in Tennessee repeated the feat with a heavier, more complex star. The field is now buzzing, with more than half a dozen teams currently working on exploding stars in 3D.

They have apparently solved one problem, figuring out how the neutrino blast wave gets enough energy to blast free from the star’s core. A close read of the article indicates that, while progress has been made, they still have many gaps of their understanding.

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Diamonds from space!

9:46 am

Researchers have discovered nano-sized diamonds inside a recovered meteorite that suggest a formation process deep within a planet at least the size of Mercury.

The researchers used transmission electron microscopes to determine their composition and morphology, and found that the diamonds contained inclusions (impurities) made of chromite, phosphate and iron-nickel sulfides.

These inclusions are common in diamonds formed underground here on Earth, but this marks the first time they’ve been found in alien rocks. That’s interesting enough on its own, but it has much bigger implications – the team calculated that these diamonds could only have formed under pressure of more than 20 gigapascals. That means they must have been born inside a planet at least as big as Mercury, and possibly up to the size of Mars.

But there’s still more to the story. The fact these diamonds made it to Earth implies that their home planet, whatever it may have been, is no longer with us, since it would take quite a cataclysm to wrench them out of their birthplace deep underground and fling them into space. Instead, the team believes the diamonds came from a planetary embryo.

Not so fast. Though the researchers themselves, in the released paper, assume that the diamonds could only have formed from inside a now destroyed large planet, this leaves out the possibility that the diamonds formed inside one of the existing terrestrial planets, were moved upward toward the surface by later geological process (as happens to diamonds are here on Earth), and then were thrown from the planet by a later nearby impact. This scenario is just as likely.

Nonetheless, this discovery is fascinating. More than anything, it illustrates the inconceivable amount of time that has passed in creating our solar system. Any of these scenarios requires time, time in quantities that no human can really understand or conceptualize.

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More delays threaten the Thirty Meter Telescope in Hawaii

9:48 pm

The coming dark age: The delaying tactics of the opponents to building the Thirty Meter Telescope in Hawaii has caused the consortium to announce that it now seriously considering moving the telescope to Spain’s Canary Islands.

These have been the most recent delaying tactics:

On Thursday, the Hawaii Senate approved a bill to ban new construction atop Mauna Kea, and included a series of audits and other requirements before the ban could be lifted. But House leaders said they don’t have plans to advance the bill. Democratic House Speaker Scott Saiki told the Honolulu Star-Advertiser that the “bill is dead on arrival in the House.”

There are also two appeals before the Hawaii Supreme Court. One challenges the sublease and land use permit issued by the Hawaii Board of Land and Natural Resources. The other has been brought by a Native Hawaiian man who says use of the land interferes with his right to exercise cultural practices and is thus entitled to a case hearing.

When the telescope gets moved, expect these barbarians in Hawaii to celebrate loudly, claiming their victory as a victory for “native rights.” What they will really be telling us is two things. First, they are against gaining new knowledge and new technology in a manner that does no one any harm. And two, they put racial rights above all, making them the worst sort of bigots.

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The search for exoplanets at Alpha Centauri

8:56 am

The search for new exoplanets orbiting the three stars of the Alpha Centauri star system is intensifying, despite significant viewing challenges and solar activity that precludes life around one star.

The system’s two sunlike stars, Alpha Centauri A and B, orbit each other closely while Proxima Centauri, a tempestuous red dwarf, hangs onto the system tenuously in a much more distant orbit. In 2016, astronomers discovered an Earth-mass planet around Proxima Centauri, but the planet, blasted by radiation and fierce stellar winds, seems unlikely to be habitable. Astrobiologists think the other two stars are more likely to host temperate, Earth-like planets.

Maksym Lisogorskyi, an astronomer at the University of Hertfordshire in Hatfield, U.K., tried to find them with an instrument on the European Southern Observatory’s (ESO’s) 3.6-meter telescope in Chile. He and his colleagues looked for Doppler shifts in the spectral lines of the stars’ light that would be caused if a planet tugged them back and forth. But Lisogorskyi told the meeting that the stars’ surfaces are turbulent, and prone to flares that also jiggle the spectral lines, masking the subtle signals from any Earth-size planets. “The lines do all kinds of things,” he says. Although Alpha Centauri has been a primary target for the planet-finding instrument since it was inaugurated in 2005, it has seen nothing so far.

Also hampering observations are the current positions of the two stars. As viewed from Earth, they are very close together, making them harder to study individually, Lily Zhao of Yale University told the meeting. More precise observations should become possible as their 80-year orbit carries them farther apart. In the meantime, Zhao and her colleagues have succeeded in ruling out the presence of giant planets around either star, based on a decade’s worth of data from three instruments on different telescopes. “There are no Jupiters in the system, but there may be plenty of Earth-sized planets still to discover,” she said.

I am skeptical of the conclusions of the astrobiologists who think there may be habitable Earth-like planets in orbit around the close binary. Binary formation makes planetary formation difficult, and even if they are there the stars’ orbits would make stable orbits unlikely. Nonetheless, the research is good, as the techniques learned will be applicable elsewhere.

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Astronomers find a dozen black holes near center of Milky Way

8:40 am

Astronomers have discovered a dozen smaller black holes orbiting near Sagittarius A* (pronounced “A-star”), the supermassive black hole at the center of the Milky Way.

Charles Hailey from Columbia University in New York and colleagues used archival data from Nasa’s Chandra X-ray telescope to come to their conclusions. They report the discovery of a dozen inactive and low-mass “binary systems”, in which a star orbits an unseen companion – the black hole.

The supermassive black hole at the centre of the Milky Way, known as Sagittarius A* (Sgr A*), is surrounded by a halo of gas and dust that provides the perfect breeding ground for the birth of massive stars. These stars live, die and could turn into black holes there. In addition, black holes from outside the halo are believed to fall under the influence of Sgr A* as they lose their energy, causing them to be pulled into its vicinity, where they are held captive by its force. Some of these bind – or “mate” – to passing stars, forming binary systems.

They have extrapolated their data to predict the existence of thousands more of these small black holes near the galaxy’s center.

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Hubble finds galaxy with no evidence of dark matter

12:29 pm

The uncertainty of science: Using the Hubble Space Telescope astronomers have discovered a nearby galaxy that apparently has little or no evidence of dark matter.

The unique galaxy, called NGC 1052-DF2, contains at most 1/400th the amount of dark matter that astronomers had expected. The galaxy is as large as our Milky Way, but it had escaped attention because it contains only 1/200th the number of stars. Given the object’s large size and faint appearance, astronomers classify NGC 1052-DF2 as an ultra-diffuse galaxy. A 2015 survey of the Coma galaxy cluster showed these large, faint objects to be surprisingly common.

But none of the ultra-diffuse galaxies discovered so far have been found to be lacking in dark matter. So even among this unusual class of galaxy, NGC 1052-DF2 is an oddball.

Van Dokkum and his team spotted the galaxy with the Dragonfly Telephoto Array, a custom-built telescope in New Mexico they designed to find these ghostly galaxies. They then used the W.M. Keck Observatory in Hawaii to measure the motions of 10 giant groupings of stars called globular clusters in the galaxy. Keck revealed that the globular clusters were moving at relatively low speeds, less than 23,000 miles per hour. Stars and clusters in the outskirts of galaxies containing dark matter move at least three times faster. From those measurements, the team calculated the galaxy’s mass. “If there is any dark matter at all, it’s very little,” van Dokkum explained. “The stars in the galaxy can account for all the mass, and there doesn’t seem to be any room for dark matter.”

The galaxy is unusual in many other ways.

The Hubble images also revealed the galaxy’s unusual appearance. “I spent an hour just staring at the Hubble image,” van Dokkum recalled. “It’s so rare, particularly these days after so many years of Hubble, that you get an image of something and you say, ‘I’ve never seen that before.’ This thing is astonishing: a gigantic blob that you can look through. It’s so sparse that you see all of the galaxies behind it. It is literally a see-through galaxy.”

The ghostly galaxy doesn’t have a noticeable central region, or even spiral arms and a disk, typical features of a spiral galaxy. But it doesn’t look like an elliptical galaxy, either. The galaxy also shows no evidence that it houses a central black hole. Based on the colors of its globular clusters, the galaxy is about 10 billion years old. Even the globular clusters are oddballs: they are twice as large as typical stellar groupings seen in other galaxies.

The bottom line here is that we have only circumstantial evidence that dark matter exists, based solely on the fact that in all other measured galaxies, the outer stars rotate much faster than they should. That rotation speed however does not guarantee the existence of dark matter, only that something is causing the fast rotation. And the lack thereof in this galaxy puts a big crimp in the theory that dark matter exists, since the theories that posit its existence almost require it to be present in every galaxy.

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The James Webb Telescope: a signpost for identifying fake news sources

11:35 am

The news yesterday that NASA will once again have to delay the launch of the James Webb Space Telescope due to a variety of technical issues and management errors not only exemplified the fundamental failure of the federal government, it also illustrated the routine failures of today’s mainstream press.

First, Webb’s new delay epitomizes the systemic incompetence of Washington. Despite being 13 years behind schedule and costing eight times more than originally planned, NASA and its contractors still couldn’t get things right.

Most of the problems have occurred with the spacecraft half of the project, which was built by Northrop Grumman in California and is undergoing testing there. During the teleconference, NASA officials, including acting Administrator Robert Lightfoot, expanded upon technical problems first reported publicly by the agency’s inspector general last month.

These include leaky valves within the spacecraft’s propulsion system and difficulties encountered during deployment tests of the sun shield. Not only did the thin, five-layer sun shield snag during the deployment, but technicians also found seven tears up to 10cm long within the material. NASA and Northrop Grumman have identified fixes for these problems, but their repair has added months of delays to the project, and engineers cannot be sure that more issues will not crop up during further testing.

Such failures, in NASA and in all big federal projects in recent years, are hardly news. Only the willfully blind or those who support wasting tax dollars to distribute pork will deny they exist.

The failures of the federal government however is not the focus of this essay. Instead, the announcement yesterday and the coverage of it by the press provides us a perfect and very obvious signpost for differentiating between the fake news sources that are generally unreliable or too often allow their biases to influence their reporting, and those sources that do a good job.

That signpost is one simple fact: Webb is not a replacement or successor to the Hubble Space Telescope, despite NASA making this false claim for decades. Hubble is an optical telescope. Webb will view the universe in the infrared. These are too entirely different things.

Yet, too many news sources today repeated NASA’s false claim, illustrating how little they know about both telescopes and their design, while revealing their complete inability to do some basic journalistic research. Instead they merely rewrite old press releases, and thus prove clearly by their bad reporting why so many people have so little respect for the modern press.

The worst examples made this false claim right in the headline:
» Read more

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Webb telescope delayed again to 2020

10:34 am

NASA has announced that it is once again delaying the launch of the James Webb Space Telescope, from 2019 to 2020.

The observatory was supposed to fly this year. But last fall, NASA bumped the launch to 2019. NASA announced the latest delay on Tuesday. “We have one shot to get this right before going into space,” said Thomas Zurbuchen, NASA’s associate administrator of science. He said some mistakes were made while preparing the telescope, and NASA underestimated the scale of the job. [emphasis mine]

None of this is a surprise. Webb is more pork than science. It was originally budgeted at $1 billion, with a planned launch in 2011. It will now cost more than $9 billion, and be delayed almost a decade. Since the project began in the early 2000s, by the time it launches it will have been in development for almost two decades, which is almost a lifetime career for some people.

And note, the article includes the lie that Webb is “a successor to the Hubble Space Telescope.” It is not. Hubble is an optical telescope. Webb will only look in the infrared. These are very different things.

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Tabby’s Star dims again

8:37 am

Scientists studying Tabby’s Star have revealed that it suddenly dimmed last week, the most since 2013, and then just as quickly returned almost to normal.

The latest dimming event started with a slow decline and ended with a rapid increase in brightness, Boyajian and her team wrote on their blog. Dust from a backward comet tail and then larger chunks from the broken-up body would explain that uneven pattern.

At this time the evidence clearly points not to alien megastructures but to clouds of fine dust whose structure and origin remain puzzling.

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Star’s close approach 70,000 years ago pinned to cometary orbits

10:03 am

Astronomers now think they have pinned the orbits of about 340 comets to another star’s close approach to our solar system 70,000 years ago.

About 70,000 years ago, when the human species was already on Earth, a small reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter. At a time when modern humans were beginning to leave Africa and the Neanderthals were living on our planet, Scholz’s star – named after the German astronomer who discovered it – approached less than a light-year from the Sun. Nowadays it is almost 20 light-years away, but 70,000 years ago it entered the Oort cloud, a reservoir of trans-Neptunian objects located at the confines of the solar system.

This discovery was made public in 2015 by a team of astronomers led by Professor Eric Mamajek of the University of Rochester (USA). The details of that stellar flyby, the closest documented so far, were presented in The Astrophysical Journal Letters.

Now two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time the nearly 340 objects of the solar system with hyperbolic orbits (very open V-shaped, not the typical elliptical), and in doing so they have detected that the trajectory of some of them is influenced by the passage of Scholz´s star.

It is likely that the close approach influenced a lot more objects, many of which might not have yet arrived in the inner solar system. Moreover, their computer models suggest that the star might have come closer to the Sun than 0.6 light years.

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Scientists theorize that Oumuamua came from a binary star system

8:17 am

Based on statistics and computer modeling, some scientists believe that the interstellar object Oumuamau likely came from stellar binary system.

For the new study, published in the journal Monthly Notices of the Royal Astronomical Society, Jackson and his co-authors set about testing how efficient binary star systems are at ejecting objects. They also looked at how common these star systems are in the Galaxy. They found that rocky objects like ‘Oumuamua are far more likely to come from binary than single star systems. They were also able to determine that rocky objects are ejected from binary systems in comparable numbers to icy objects.

Their conclusion does make sense, though any good scientist would retain a gigantic sense of skepticism. While it is statistically reasonable to conclude that a majority of interstellar objects should come from binary systems, there is no guarantee that Oumuamua in particular did so. Even if the odds were one in a million, there is always that one, and the universe often seems prone to fooling us.

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Kepler to run out of fuel in the coming months

1:08 pm

After nine years of success, the Kepler space telescope is running out of fuel, which will force an end to the mission sometime in the next several months.

The Kepler team is planning to collect as much science data as possible in its remaining time and beam it back to Earth before the loss of the fuel-powered thrusters means that we can’t aim the spacecraft for data transfer. We even have plans to take some final calibration data with the last bit of fuel, if the opportunity presents itself.

Without a gas gauge, we have been monitoring the spacecraft for warning signs of low fuel— such as a drop in the fuel tank’s pressure and changes in the performance of the thrusters. But in the end, we only have an estimate – not precise knowledge. Taking these measurements helps us decide how long we can comfortably keep collecting scientific data.

They are doing a dance here. If they run out of fuel while collecting data, that data will be lost. If they stop collecting data too soon, however, to transmit it to Earth, they will not maximize the data obtained.

Meanwhile, the next exoplanet hunter, TESS, is scheduled for launch on April 16 on a Falcon 9 rocket.

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Chandra looks back at the Crab Nebula

8:22 am

Link here. It is almost twenty years since the Chandra X-Ray Observatory was launched, and in celebration the science team have released another X-ray image of the Crab Nebula, taken in 2017 in league with an optical image from the Hubble Space Telescope and an infrared image from the Spitzer Space Telescope. They have also provided links to all similar past images, going back to 1999.

Some of the images are actually videos, in 2002 and 2011, showing the Crab’s dynamic nature. You can actually see flares and waves of radiation rippling out from its center.

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University of Chicago to cease support of Yerkes in October 2018

2:26 pm

The University of Chicago announced today that it will cease all support of the Yerkes Observatory, home of the world’s largest refractive telescope, in October 2018.

The University of Chicago has announced plans to wind down its activities at Yerkes Observatory in Williams Bay, Wis., over the next six months and to formally cease on-site operations by Oct. 1, 2018.

The upcoming summer season will therefore be the final season of University activities at Yerkes. The University is announcing the plans well in advance in order to engage with Yerkes staff and nearby communities, including the village of Williams Bay, in considering long-term plans for the property.

The telescope is no longer useful for scientific research, but it is historically important, and as the press release admits, “has continued to make important contributions through its education and outreach programs.” And while I can understand their decision, they sure didn’t leave the staff at Yerkes much time to find new backers. When the National Science Foundation decided it was dropping support for its telescopes at Kitt Peak, it gave them literally several years to round up new support.

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Webb faces more delays, cost overruns

7:23 am

A new GAO report released yesterday says that the James Webb Space Telescope faces further delays and cost overruns.

This is par for the course. Webb has become an incredible boondoggle. I hope it eventually gets launched and works, but its gigantic cost, $8 to $9 billion (compared to an original $1 billion budget), and delayed schedule suggests that this was not the right way for NASA or the astronomical community to build its space telescopes. Further, this quote from the story suggests something fundamentally wrong:

The GAO report also noted that, during the sunshield deployment exercises, Northrop discovered several tears in the material which it attributed to “workmanship error.” Those tears can be repaired but may consume more schedule reserve.

Is this thing really going to work? I really hope so, but have been increasingly doubtful as the delays and problems have piled up.

Meanwhile, NASA and the astronomical community is still pushing to get funding for its next “Webb,” the Wide-Field Infrared Survey Telescope (WFIRST). This project, similar in scope as Webb, is hardly off the ground and already has budget overrun issues. The Trump administration recommended cancelling in its budget proposal earlier this month, but I would be surprised if that recommendation goes through, considering the pork this new project represents.

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New backers to run Arecibo

8:27 am

The National Science Foundation this week revealed the make-up of the consortium that is taking over the operation of the Arecibo radio telescope in Puerto Rico.

The new agreement is valued at $20.15 million over five years, subject to the availability of funds, and is scheduled to begin April 1, according to the statement.

The new partnership represents a mixture of academic and corporate interests. The Universidad Metropolitana in San Juan, Puerto Rico, and Yang Enterprises Inc. in Oviedo, Florida, will partner with [the University of Central Florida] to manage the observatory. The team plans to expand the capabilities of the telescope, officials said.

This relieves the National Science Foundation (and the taxpayers) of the the cost burden for this facility, at least directly.

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Hubble finds new figure for universe expansion rate

6:58 am

The uncertainty of science: Using data from the Hubble Space Telescope astronomers have found evidence that universe’s expansion rate is faster than estimated in previous measurements.

The new findings show that eight Cepheid variables in our Milky Way galaxy are up to 10 times farther away than any previously analyzed star of this kind. Those Cepheids are more challenging to measure than others because they reside between 6,000 and 12,000 light-years from Earth. To handle that distance, the researchers developed a new scanning technique that allowed the Hubble Space Telescope to periodically measure a star’s position at a rate of 1,000 times per minute, thus increasing the accuracy of the stars’ true brightness and distance, according to the statement.

The researchers compared their findings to earlier data from the European Space Agency’s (ESA) Planck satellite. During its four-year mission, the Planck satellite mapped leftover radiation from the Big Bang, also known as the cosmic microwave background. The Planck data revealed a Hubble constant between 67 and 69 kilometers per second per megaparsec. (A megaparsec is roughly 3 million light-years.)

However, the Planck data gives a constant about 9 percent lower than that of the new Hubble measurements, which estimate that the universe is expanding at 73 kilometers per second per megaparsec, therefore suggesting that galaxies are moving faster than expected, according to the statement.

“Both results have been tested multiple ways, so barring a series of unrelated mistakes, it is increasingly likely that this is not a bug but a feature of the universe,” Riess said. [emphasis mine]

I should point out that one of the first big results from Hubble in 1995 (which also happened to be the subject one of my early published stories), the estimate then for the Hubble constant was 80 kilometers per second per megaparsec. At the time, the astronomers who did the research were very certain they had it right. Others have theorized that the number could be as low as 30 kilometers per second per megaparsec.

What is important about this number is that it determines how long ago the Big Bang is thought to have occurred. Lower numbers mean it took place farther in the past. Higher numbers mean the universe is very young.

That scientists keep getting different results only suggests to me that they simply do not yet have enough data to lock the number down firmly.

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Interstellar object Oumuamua tumbling chaotically

8:46 am

A new analysis of the data obtained when the interstellar object Oumuamua flew through the solar system in October 2016 suggests that it is tumbling in a chaotic manner, and that the surface is spotty.

Straight away, they discovered that ‘Oumuamua wasn’t spinning periodically like most of the small asteroids and bodies that we see in our solar system. Instead, it is tumbling, or spinning chaotically, and could have been for many billions of years.

While it is difficult to pinpoint the exact reason for this, it is thought that `Oumuamua impacted with another asteroid before it was fiercely thrown out of its system and into interstellar space. Dr Fraser explains: “Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again.

To me, this data settles the question about whether Oumuamua is not an artificial structure. It is not. If it were, an impact that would have caused this kind of tumbling would have almost certainly destroyed it. Instead, it likely broke the original bolide up, producing many fragments, including Oumuamua and its elongated shape.

As for the object’s spottiness:

Dr Fraser explains: “Most of the surface reflects neutrally but one of its long faces has a large red region. This argues for broad compositional variations, which is unusual for such a small body.”

It is really a shame we couldn’t get a closer look before it sped away.

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More info on Trappist-1 solar system

9:25 am

Astronomers, using ground-based and orbiting telescopes, have obtained more information about the seven Earth-sized exoplanets that orbit the star Trappist-1 forty light years away.

First, a European effort has found that the planets probably all have loads of water.

A new study has found that the seven planets orbiting the nearby ultra-cool dwarf star TRAPPIST-1 are all made mostly of rock, and some could potentially hold more water than Earth. The planets’ densities, now known much more precisely than before, suggest that some of them could have up to 5 percent of their mass in the form of water — about 250 times more than Earth’s oceans. The hotter planets closest to their parent star are likely to have dense steamy atmospheres and the more distant ones probably have icy surfaces. In terms of size, density and the amount of radiation it receives from its star, the fourth planet out is the most similar to Earth. It seems to be the rockiest planet of the seven, and has the potential to host liquid water.

Data from the Hubble Space Telescope has meanwhile found that three of the seven planets do not have hydrogen in their atmospheres, which at first seems to contradict the European data.

The Hubble observations took advantage of the fact that the planets cross in front of their star every few days. Using the Wide Field Camera 3, astronomers made spectroscopic observations in infrared light, looking for the signature of hydrogen that would filter through a puffy, extended atmosphere, if it were present. “The planets are close enough to their host star, and they have very short orbital periods, which means there are lots of opportunities to make observations,” Lewis said.

Although Hubble did not find evidence of hydrogen, the researchers suspect the planetary atmospheres could have contained this lightweight gaseous element when they first formed. The planets may have formed farther away from their parent star in a colder region of the gaseous protostellar disk that once encircled the infant star.

The Hubble results are actually not very significant. They show only that they did not detect hydrogen in the atmospheres of these three exoplanets, which does not mean it isn’t there. Moreover, this Hubble press release appears to have been issued as much to sell the James Webb Space Telescope and to say that Hubble is looking at Trappist-1 also!

I should add that all of these results are very uncertain. We are looking at something that is very small and is also very far away. Any data obtained is certainly not a precise measurement of what is actually there, only a mere hint.

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NASA funds a cubesat-sized ultra-violet telescope

2:50 pm

NASA has funded a cubesat-based ultra-violet telescope to launch in 2021.

SPARCS is a CubeSat built of six cubical units, each about four inches on a side. These are joined to make a spacecraft two units wide by three long in what is termed a 6U spacecraft. Solar power panels extend like wings from one end. “In size and shape, SPARCS most resembles a family-size box of Cheerios,” Shkolnik said.

The spacecraft will contain three major systems — the telescope, the camera, and the operational and science software. Along with Shkolnik, SESE astronomers Paul Scowen, Daniel Jacobs, and Judd Bowman will oversee the development of the telescope and camera, plus the software and the systems engineering to pull it all together. The telescope uses a mirror system with coatings optimized for ultraviolet light. Together with the camera, the system can measure very small changes in the brightness of M dwarf stars to carry out the primary science of the mission.

As I have noted numerous times recently, the space industry is splitting between large manned projects and tiny unmanned ones. While certain unmanned probes will always have to be larger, the ability to build and launch the same capabilities at a smaller size is lowering cost and allowing more probes to be launched.

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NASA renames Swift telescope to honor Neil Gehrels

10:48 am

NASA has renamed the Swift space telescope, designed to quickly detect and observe fast transient events in space like gamma ray bursts, to honor the late Neil Gehrels, the man who led the project from day one.

During a presentation at a NASA town hall meeting at the 231st Meeting of the American Astronomical Society here, Thomas Zurbuchen, NASA associate administrator for science, said that Swift would now be known as the Neil Gehrels Swift Observatory.

Gehrels, who died in February 2017, had been principal investigator for Swift, a mission launched in 2004. The spacecraft was designed to be able to rapidly respond to transient events, such as gamma-ray bursts, observing them at wavelengths ranging from gamma rays to visible light.

“Neil wore many hats in service to the astrophysics community,” said Paul Hertz, director of NASA’s astrophysics division, at a later press conference at the meeting. In addition to being the principal investigator for Swift, had served as project scientist on the Compton Gamma-Ray Observatory and Fermi missions. At the time of his death last year he was project scientist for the Wide-Field Infrared Survey Telescope, NASA’s next flagship astronomy mission after the James Webb Space Telescope.

Knowing astronomers, they will now refer to this observatory as the NGSO. Not I. It will be “Gehrels Swift” to me, whenever I need to mention it. Gehrels was one of the most friendly, open, and easy-to-work-with astronomers I ever had to deal with. He is sorely missed.

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First six segments of Extremely Large Telescope cast

8:23 am

The first six mirror segments of the European Southern Observatory’s Extremely Large Telescope have been successfully cast.

These segments will form parts of the ELT’s 39-metre main mirror, which will have 798 segments in total when completed. The ELT will be the largest optical telescope in the world when it sees first light in 2024.

The 39-metre-diameter primary mirror of ESO’s Extremely Large Telescope will be by far the largest ever made for an optical-infrared telescope. Such a giant is much too large to be made from a single piece of glass, so it will consist of 798 individual hexagonal segments, each measuring 1.4 metres across and about 5 centimetres thick. The segments will work together as a single huge mirror to collect tens of millions of times as much light as the human eye.

The segments must now be cooled, then their surfaces ground and polished to the right shape. If all goes right, they will make more than 900 segments (with about a 130 as spares), manufactured to have the telescope operational by 2024.

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Was the solar system formed inside a giant bubble?

10:28 am

Don’t bet the house on this! Astronomers have come up with a new theory for the formation of the solar system, that it was formed inside a giant bubble inside a Wolf-Rayet star, in order to explain the known ratios of certain isotopes here.

The new theory for how the solar system formed starts with an extremely massive star known as a Wolf-Rayet star. Of all the stars in the universe, these stars burn the hottest. Because they are so hot, they also have exceptionally strong stellar winds.

As a Wolf-Rayet star sheds its outer layers – a normal end-of-life process for a giant star – its strong stellar winds plow through its loosely held cloak of material, forming densely shelled bubbles. According to the study, the solar system could have formed inside of one of these bubbles.

While this theory would explain a number of mysteries about the ratios of aluminum-26 and iron-60 in our solar system, which correspond closer to those in a Wolf-Rayet star than the galaxy itself, it is quite far-fetched. More hard data is necessary, including real evidence of such things actually happening in such stars, before it can be taken very seriously.

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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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