Tag: astronomy

The mystery of Tabby’s star deepens

7:07 am

Astronomers looking at the light variations of the star dubbed by some Tabby’s star have become even more baffled.

Spurred by a controversial claim that the star’s brightness gradually decreased by 14 percent from 1890 to 1989, Montet and Simon decided to investigate its behavior in a series of Kepler calibration images that had not previously been used for scientific measurements. “We thought that these data could confirm or refute the star’s long-term fading, and hopefully clarify what was causing the extraordinary dimming events observed in KIC 8462852,” explained Simon.

Simon and Montet found that, over the first three years of the Kepler mission, KIC 8462852 dimmed by almost 1 percent. Its brightness then dropped by an extraordinary 2 percent over just six months, remaining at about that level for the final six months of the mission. The pair then compared this with more than 500 similar stars observed by Kepler and found thata small fraction of them showed fading similar to that seen in KIC 8462852 over the first three years of Kepler images. However, none exhibited such a dramatic dimming in just six months, or a total change in brightness of 3 percent.

“The steady brightness change in KIC 8462852 is pretty astounding,” said Montet. “Our highly accurate measurements over four years demonstrate that the star really is getting fainter with time.  It is unprecedented for this type of star to slowly fade for years, and we don’t see anything else like it in the Kepler data.” 

At the moment, there is no good theory based on what astronomers know of stellar evolution to explain this star’s behavior. This does not mean the only explanation left is that aliens are building a Dyson sphere around the star, but it also leaves everyone at a loss to explain what is happening.

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Dark matter unnecessary?

9:06 pm

The uncertainty of science: A new analysis of the infrared data from 153 galaxies using the Spitzer Space Telescope suggests that dark matter might not be necessary to explain the rotation of galaxies.

First, this concise and nicely written explanation from the link of why dark matter has been proposed:

Newton’s laws of motion predict that planets that revolve closer to a star move faster than those that are farther away. In principle this should also hold true for stars circling the cores of galaxies, but for nearly a century, astronomers have seen that stars near the outskirts of galaxies orbit at nearly the same velocities as ones near galactic centers.

To explain why these outlying stars travel as quickly as they do without flying out into the void beyond, researchers came up with the idea of dark matter, a substance whose gravitational pull is thought to keep whirling stars in check. Scientists have largely ruled out all known particles as possible explanations for dark matter, and the consensus is that dark matter must be a kind of invisible, intangible material that is only detectable via its gravitational influence.

However, despite decades of trying, researchers have failed to capture a single mote of dark matter, even though it is supposed to make up roughly five-sixths of all matter in the universe. This raises the possibility that dark matter might not be real.

The new research, which I must admit I do not really understand, supposedly suggests that dark matter is unnecessary to explain the motions of stars.

Previous analyses of the orbital velocities of the stars in galaxies often depended on visible wavelengths of light. However, the stars that produce the most visible light are relatively short-lived and prone to fluctuations, and so may not provide the best picture of how matter is scattered overall throughout a galaxy. Instead, McGaugh and his colleagues analyzed near-infrared images collected by NASA’s Spitzer Space Telescope over the past five years. “The stars that generate the most near-infrared light are red giants, that are pretty stable in their output, and so are much better representative of a galaxy’s total mass of stars,” McGaugh said.

The researchers found an extraordinarily close association between the location of normal matter and the way it accelerates around the centers of galaxies. “We were surprised at how tight that relationship was,” McGaugh said. “It looks tantamount to a law of nature.”

Neither the article nor the scientists who did this research however explain clearly how this tight association negates the need for dark matter.

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Hubble captures on-going comet break-up

10:47 am

animation of comet debris

Cool image time! The animation to the right, taken over three days by the Hubble Space Telescope, cropped and reduced to fit here, shows the debris flying away from Comet 332P/Ikeya-Murakami. It also shows a new piece of debris close to the comet on the lower left.

The research team calculated that the comet probably shed material over several months, between October and December 2015. Jewitt suggests that even some of the ejected pieces have themselves fallen to bits in a kind of cascading fragmentation. “Our analysis shows that the smaller fragments are not as abundant as one might expect based on the number of bigger chunks,” he said. “This is suggestive that they’re being depleted even in the few months since they were launched from the primary body. We think these little guys have a short lifetime.”

Hubble’s sharp vision also spied a chunk of material close to the comet, which may be the first salvo of another outburst. The remnant from still another flare-up, which may have occurred in 2012, is also visible. The fragment may be as large as Comet 332P, suggesting the comet split in two. But the icy remnant wasn’t spotted until Dec. 31, 2015, by the Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) telescope in Hawaii, in work supported by the Near-Earth Object Observations program in NASA’s Planetary Defense Coordination Office. That discovery prompted Jewitt and colleagues to request Hubble time to look at the comet in detail. Around the same time, astronomers around the world began to notice a cloudy patch of material near the comet – which Hubble later resolved into the 25 pieces.

The scientists think they actually “may be seeing a comet fragmenting itself into oblivion.”

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NASA extends Hubble contract through 2021

5:00 pm

NASA has extended its contract with Lockheed Martin for the operation of the Hubble Space Telescope until June 2021.

This contract is for non-science operations. Science operations are controlled by the Space Telescope Science Institute in Baltimore.

Note that when the last repair mission to Hubble took place in 2009, they expected it to add five years to the telescope’s life. This contract says they now expect it to last at least until 2021, which will also be 31 years after its launch and almost forty years since its actual construction. Not a bad track record when you think about it, especially since its original mission was set at 15 years, ending in 2005.

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Scientists discover exoplanets orbiting both stars of binary system

9:46 am

Worlds without end: Scientists have discovered a stellar binary system which has giant exoplanets orbiting each of the system’s stars.

The twin stars studied by the group are called HD 133131A and HD 133131B. The former hosts two moderately eccentric planets, one of which is, at a minimum, about 1 and a half times Jupiter’s mass and the other of which is, at a minimum, just over half Jupiter’s mass. The latter hosts one moderately eccentric planet with a mass at least 2.5 times Jupiter’s.

The two stars themselves are separated by only 360 astronomical units (AU). One AU is the distance between the Earth and the Sun. This is extremely close for twin stars with detected planets orbiting the individual stars. The next-closest binary system that hosts planets is comprised of two stars that are about 1,000 AU apart.

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New and very distance outer solar system objects beyond Neptune

10:11 am

Astronomers have discovered several new objects orbiting the Sun at extremely great distances beyond the orbit of Neptune.

The most interesting new discovery is 2014 FE72:

Another discovery, 2014 FE72, is the first distant Oort Cloud object found with an orbit entirely beyond Neptune. It has an orbit that takes the object so far away from the Sun (some 3000 times farther than Earth) that it is likely being influenced by forces of gravity from beyond our Solar System such as other stars and the galactic tide. It is the first object observed at such a large distance.

This research is being done as part of an effort to discover a very large planet, possibly as much as 15 times the mass of Earth, that the scientists have proposed that exists out there.

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More details about Proxima Centauri’s Earthlike exoplanet

8:50 am

Link here. Lots of background into the discovery itself, but I think these paragraphs really sum things up:

“The search for life starts now,” says Guillem Anglada-Escudé, an astronomer at Queen Mary University of London and leader of the team that made the discovery.

Humanity’s first chance to explore this nearby world may come from the recently announced Breakthrough Starshot initiative, which plans to build fleets of tiny laser-propelled interstellar probes in the coming decades. Travelling at 20% of the speed of light, they would take about 20 years to cover the 1.3 parsecs from Earth to Proxima Centauri.

Proxima’s planet is at least 1.3 times the mass of Earth. The planet orbits its red-dwarf star — much smaller and dimmer than the Sun — every 11.2 days. “If you tried to pick the type of planet you’d most want around the type of star you’d most want, it would be this,” says David Kipping, an astronomer at Columbia University in New York City. “It’s thrilling.”

The human race now has a real interstellar target to aim for. Don’t be surprised if we get there sooner than anyone predicts.

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TMT will probably not go to India

10:04 am

An Indian astronomer, in testimony to India’s parliament, has explained that for engineering and technical reasons India will likely not be the new location of the Thirty Meter Telescope (TMT).

Essentially, the skies are clearer in the Canary Islands and in Chile.

This story is important in that it confirms that the consortium building TMT is now very seriously considering abandoning Hawaii, and might already have decided to do so. It also suggests that the Canary Islands is in the lead as the new location, since they want a site that can see the skies of the northern hemisphere, something that won’t be possible in Chile.

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Physicists fail to find sterile neutrino

9:02 am

The uncertainty of science: A year’s collection of data using IceCube, a gigantic neutrino telescope built in the icecap of Antarctica, has found no evidence of a theorized fourth type of neutrino.

To search for sterile neutrinos, Halzen’s team looked for the arrival of muon neutrinos that started life on the other side of Earth. These were originally produced by the collision of cosmic rays with air molecules in the atmosphere, and passed through the planet to reach the detector. The IceCube team hoped to find a dearth of muon neutrinos at particular energies. That would have suggested that some muon neutrinos had temporarily mutated into sterile neutrinos during their voyage.

But, after analysing the results of a year’s worth of data, the researchers found no feature suggesting the existence of sterile neutrinos around 1 eV. This is line with results from the European Space Agency’s Planck observatory, which concluded from cosmological evidence that there should only be three families of neutrinos in that mass range. “I hope that with our result and with the Planck result we are slowly walking our way back from this story,” says Halzen. The IceCube team are still taking data in their sterile neutrino hunt, but don’t expect their results to change, he adds.

Despite this null result, there is still a possibility that sterile neutrinos exist, but not at the mass predicted.

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A big Perseid meteor shower on Friday?

8:29 am

According to a new computer model of the Perseid meteor shower, astronomers predict that there could be a big peak of shooting stars on Friday.

Russian astronomer Mikhail Maslov and Finnish astronomer Esko Lyytinen predict that this year the Earth will pass through a stream of cometary material shifted towards us by Jupiter’s gravitational field. According to their model, and work by French scientist Jeremie Vaubaillon, we could see a steep rise in activity from late evening on 11 August to 0500 BST on 12 August.

The Perseids are typically active from around 17 July to 24 August, although for most of that period only a few meteors an hour will be visible. During the peak, and if the predictions by Maslov, Lyytinen and Vaubaillon are right, as many as 100 meteors or more may be seen each hour. This year, the light from the waxing gibbous Moon will interfere to some extent for the first part of the night, so observers are advised to look out in the early morning hours after midnight when the Moon is very low in the sky or has set.

If this is true, Diane and I might have lucked out, as we will be heading for our annual Grand Canyon hike to the bottom on Friday.

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The mystery of Tabby’s Star deepens

11:15 pm

The uncertainty of science: New data from Kepler has made it even more difficult for scientists to explain the strange fluctuations and dimming of Tabby’s Star.

KIC 8462852, as it is more properly known, flickers so erratically that one astronomer has speculated that nothing other than a massive extraterrestrial construction project could explain its weird behaviour. A further look showed it has been fading for a century. Now, fresh analysis suggests the star has also dimmed more rapidly over the past four years – only adding to the enigma. “It seems that every time someone looks at the star, it gets weirder and weirder,” says Benjamin Montet at the California Institute of Technology, who led the study.

There are as yet no natural explanations for the star’s dimming.

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Poll shows Hawaiians strongly favor TMT

11:14 pm

A new poll shows that by a 2 to 1 margin Hawaiians are in favor of building the Thirty Meter Telescope (TMT).

  • 89 percent of Hawaii Island residents agree there should be a way for science and Hawaiian culture to co-exist on Maunakea
  • 76 percent of Hawaii Island residents agree that TMT will help create good paying jobs and economic and educational benefits for those living on Hawaii Island
  • 70 percent of Hawaii Island residents agree that failure to move forward with TMT will hurt educational opportunities for Hawaii Island children with the termination of TMT’s annual $1 million contribution to the THINK Fund and workforce pipeline program
  • 69 percent of Hawaii Island residents agree that TMT has followed a lengthy approval process, so work should proceed

Based on what I’ve seen for the past forty years, this poll will mean nothing. The poll also found that the native Hawaiian population was much less supportive, with only 46 percent in support of the project and 45 percent opposed. And since the Democratic Party that runs Hawaii is a party that cares almost exclusively for the concerns of oppressed minorities over that of the non-native majority, you can bet they will do what the native population wants. The telescope will never get built in Hawaii, and the consortium building TMT had better face this reality and find another location.

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Astrobiologists meet to better their search for exoplanet life

9:25 am

The uncertainty of science: Astrobiologists are meeting this week in Seattle to discuss and refine their methods for detecting astrobiology on exoplanets.

The Seattle meeting aims to compile a working list of biosignature gases and their chemical properties. The information will feed into how astronomers analyse data from NASA’s James Webb Space Telescope, slated for launch in 2018. The telescope will be able to look at only a handful of habitable planets, but it will provide the first detailed glimpse of what gases surround which world, says Nikole Lewis, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland.

No single gas is likely to be a slam-dunk indicator of alien life. But Domagal-Goldman hopes that the workshop will produce a framework for understanding where scientists could trip themselves up. “We don’t want to have a great press release,” he says, “and then a week later have egg on everybody’s faces.”

A few years ago I was told by one astronomer that the field’s biggest and most exciting area of research in the coming decades will be the effort to study the thousands exoplanets they only just discovered. I agree. The Webb telescope might have been built to study cosmology, but the data it will produce about exoplanets will be much more real and less uncertain, thus making it more compelling and convincing.

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“They can’t be real.”

8:56 am

The uncertainty of science: Astronomers have now detected and measured a new class of large but very dim galaxy that previously was not expected to exist.

‘Ultradiffuse’ galaxies came to attention only last year, after Pieter van Dokkum of Yale University in New Haven, Connecticut, and Roberto Abraham of the University of Toronto in Canada built an array of sensitive telephoto lenses named Dragonfly. The astronomers and their colleagues observed the Coma galaxy cluster 101 megaparsecs (330 million light years) away and detected 47 faint smudges.

“They can’t be real,” van Dokkum recalls thinking when he first saw the galaxies on his laptop computer. But their distribution in space matched that of the cluster’s other galaxies, indicating that they were true members. Since then, hundreds more of these galaxies have turned up in the Coma cluster and elsewhere.

Ultradiffuse galaxies are large like the Milky Way — which is much bigger than most — but they glow as dimly as mere dwarf galaxies. It’s as though a city as big as London emitted as little light as Kalamazoo, Michigan.

More significantly, they have now found that these dim galaxies can be as big and as massive as the biggest bright galaxies, suggesting that, surprise!, there are a lot more stars and mass hidden out there and unseen than anyone had previously predicted.

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WIMP detector finds nothing

8:36 am

The uncertainty of science: A detector buried a mile underground so that it could only detect the predicted Weak Interacting Massive Particles (WIMP) thought to comprise dark matter has found nothing

Dark matter is thought to account for more than four-fifths of the mass in the universe. Scientists are confident of its existence because the effects of its gravity can be seen in the rotation of galaxies and in the way light bends as it travels through the universe, but experiments have yet to make direct contact with a dark matter particle. The LUX experiment was designed to look for weakly interacting massive particles, or WIMPs, the leading theoretical candidate for a dark matter particle. If the WIMP idea is correct, billions of these particles pass through your hand every second, and also through the Earth and everything on it. But because WIMPs interact so weakly with ordinary matter, this ghostly traverse goes entirely unnoticed.

…“We worked hard and stayed vigilant over more than a year and a half to keep the detector running in optimal conditions and maximize useful data time,” said Simon Fiorucci, a physicist at Berkeley Lab and Science Coordination Manager for the experiment. “The result is unambiguous data we can be proud of and a timely result in this very competitive field—even if it is not the positive detection we were all hoping for.”

This null result, which has its own uncertainties that require confirmation by another experimental test, places significant constraints on the possible nature of the dark matter particle, assuming it exists. And if confirmed, this result makes the hunt to explain the gravitational data of galaxy rotation, something that has been confirmed repeatedly, far more difficult.

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Nearby exoplanets have Earthlike atmospheres

10:58 am

Worlds without end: New data from Hubble suggests that two rocky exoplanets only 40 light years away have atmospheres more similar to Earth’s than to that of gas giants.

Specifically, they discovered that the exoplanets TRAPPIST-1b and TRAPPIST-1c, approximately 40 light-years away, are unlikely to have puffy, hydrogen-dominated atmospheres usually found on gaseous worlds. “The lack of a smothering hydrogen-helium envelope increases the chances for habitability on these planets,” said team member Nikole Lewis of the Space Telescope Science Institute (STScI) in Baltimore, Maryland. “If they had a significant hydrogen-helium envelope, there is no chance that either one of them could potentially support life because the dense atmosphere would act like a greenhouse.”

The actual make-up of these atmospheres remains unknown. Also, the central star, a red dwarf, is estimated to be about a half billion years old. Both the star’s make-up — red dwarfs are not as rich in elements as a G-type sun — and age do not provide much margin for the development of life.

Nonetheless, the new data increases again the likelihood that we will eventually find habitable worlds orbiting other stars, and we will find them in large numbers.

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TMT likely to abandon Hawaii

3:55 pm

Officials from the consortium that is building the Thirty Meter Telescope (TMT) have revealed that they are looking very seriously at alternative locations.

Officials behind the proposed Thirty Meter Telescope (TMT) are considering new locations for the $1.4bn facility, and expect to decide whether to opt for a new site early next year. The TMT is due to be built on Hawaii’s Mauna Kea mountain but, following protests from local residents, its building permit was revoked last December by the state’s Supreme Court. New locations that are being considered include Baja California in Mexico, the Canary Islands and Chile, as well as locations in India and China.

They claim that Hawaii is still their first choice, but if they don’t see any progress by summer in the permitting process, I expect them to tell Hawaii to go to hell (though not in those words) and pick somewhere else.

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