Tag: astronomy

LSST’s giant coating chamber arrives in Chile

2:54 pm

The giant coating chamber that will be used to coat the mirrors for the Large Synoptic Survey Telescope has arrived in Chile.

The Coating Chamber and its associated equipment will share this level with the camera maintenance rooms, the vertical platform lift, and the shipping and receiving area. The Coating Chamber will be used to coat LSST’s mirrors when they arrive on Cerro Pachón, and to re-coat the mirrors periodically during Operations.

LSST will conduct a 10-year survey, and during this period its mirrors will be exposed to the elements each night as the telescope surveys the sky through the open side of the observatory dome. Over time the mirrors will get dusty, and the mirror coatings may develop small blemishes that eventually affect the telescope’s performance. To ensure that LSST continues to collect the sharpest possible images of the night sky, its mirrors will undergo periodic washing and recoating. It’s anticipated that the Primary/Tertiary Mirror (M1M3) will need to be recoated every two years, and the Secondary Mirror (M2) every five years, during the 10-year survey. Both the washing and recoating will be done inside the observatory; special equipment will be used to remove and transport the mirrors from the telescope to the washing station and coating chamber.

LSST will essentially be imaging the entire visible sky nightly, making it possible over time to track sudden events, such as supernovae, as they happen.

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China still struggling to find scientists to run FAST radio telescope

8:32 am

China is still finding it difficult to hire the scientists necessary to run its FAST radio telescope, the largest single dish radio telescope in the world.

And why is that?

For job candidates, the major stumbling blocks often are financial incentives and research independence, researchers told the South China Morning Post. The telescope’s remote location also may give candidates pause.

George Smoot, a Hong Kong University of Science and Technology professor who won the Nobel Prize in physics in 2006, said candidates interested in working in a more developed setting might think twice about spending a lot of time in an area known for its traditional rural villages.

“Another issue is how much the Chinese Academy of Sciences will influence and direct activities there,” Smoot said. “It is an issue to people unless they have some straight link.” [emphasis mine]

It must always be remembered that nothing in China is done without the government’s approval. For western astronomers, used to having a great deal of independence, this fact makes working there somewhat unappealing.

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Danish astronomers question gravitational wave detection

9:23 am

The uncertainty of science: A team of Danish astronomers have questioned the gravitational wave detection achieved in the past few years by the LIGO gravitational wave telescopes.

The details are complex and very much in dispute, and the position of these Danish astronomers is very much in the minority, but their doubts have not been dismissed, and illustrate well the best aspects science. The article also outlines how the physics community and the LIGO scientists have welcomed the skepticism, even as they have doubts about the claims of the Danish astronomers. This is the hallmark of good science, and lends weight to the work at LIGO.

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Head of Webb investigation: Webb was “a step too far”

9:11 am

The head of an investigation panel into the James Webb Space Telescope admitted this week that, though he and the panel fully support the telescope’s completion and launch, he also believes the telescope was too ambitious and “a step too far.”

Speaking at a meeting of the Committee on Astronomy and Astrophysics of the National Academies’ Space Studies Board Oct. 29, Tom Young said that while the mission may ultimately be a success, its difficulties provide lessons as NASA considers future large astronomy missions in the next decadal survey.

“I, personally, have come to the conclusion that JWST had too many inventions, too much risk, and was a step too far,” he said at the end of a presentation about the review board’s work.

Young emphasized that he was neither opposed to JWST being completed nor had doubts it could be done successfully. “There are a group people who are diehard supporters of JWST, and there are others who support it, but they’re really angry at the cost growth and the schedule delays,” he said.

You think? Webb was supposed to cost about $500 million, and launch in 2007. Its budget is now almost $10 billion, and it will not launch before 2021. In the process it has destroyed the entire astronomy program at NASA, preventing the construction of any other space telescopes.

The key question is whether the astronomy community or NASA has learned anything from this disaster. I personally am doubtful, since they are still pushing for WFIRST, a similar big boondoggle that will cost billions and is already overbudget and behind schedule, though it is only in its design stage.

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Early Milky Way collision uncovered by Gaia

12:21 pm

Data from the space telescope Gaia has revealed a Milky Way merger event that occurred about 10 billion years ago.

Using the first 22 months of observations, a team of astronomers led by Amina Helmi, University of Groningen, The Netherlands, looked at seven million stars – those for which the full 3D positions and velocities are available – and found that some 30,000 of them were part of an ‘odd collection’ moving through the Milky Way. The observed stars in particular are currently passing by our solar neighbourhood.

We are so deeply embedded in this collection that its stars surround us almost completely, and so can be seen across most of the sky.

Even though they are interspersed with other stars, the stars in the collection stood out in the Gaia data because they all move along elongated trajectories in the opposite direction to the majority of the Galaxy’s other hundred billion stars, including the Sun. They also stood out in the so-called Hertzprung-Russell diagram – which is used to compare the colour and brightness of stars – indicating that they belong to a clearly distinct stellar population.

The sheer number of odd-moving stars involved intrigued Amina and her colleagues, who suspected they might have something to do with the Milky Way’s formation history and set to work to understand their origins. In the past, Amina and her research group had used computer simulations to study what happens to stars when two large galaxies merge. When she compared those to the Gaia data, the simulated results matched the observations. “The collection of stars we found with Gaia has all the properties of what you would expect from the debris of a galactic merger,” says Amina, lead author of the paper published today in Nature.

At the time, the two galaxies were both probably about the same size, approximately equivalent to the Magellanic Clouds.

Must I mention that there is some uncertainty here? The data is good, and the conclusions seem quite reasonable. At the same time, the data is still somewhat thin. We need a lot more Gaia-type telescopes mapping out the motions and positions of all the stars of the Milky Way in far more detail before the uncertainties here will shrink.

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Timelapse movie of Supernova 1987A’s evolution from 1992 to 2017

9:42 am

Cool movie time! An astronomy graduate student in Toronto has created a movie showing the steady evolution of the shock wave from Supernova 1987A, the first supernova visible to the naked eye since the discovery of the telescope, during the past twenty-five years.

Yvette Cendes, a graduate student with the University of Toronto and the Leiden Observatory, has created a time-lapse showing the aftermath of the supernova over a 25-year period, from 1992 to 2017. The images show the shockwave expanding outward and slamming into debris that ringed the original star before its demise.

In an accompanying paper, published in the Astrophysical Journal on October 31st, Cendes and her colleagues add to the evidence that the expanding remnant is shaped—not like a ring like those of Saturn’s—but like a donut, a form known as a torus. They also confirm that the shockwave has now picked up some one thousand kilometres per second in speed. The acceleration has occurred because the expanding torus has punched through the ring of debris.

The animation, which I have embedded below the fold, uses images produced by an array radio telescopes in Australia.
» Read more

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Hawaii Supreme Court rules in favor of TMT

9:04 am

Hawaii’s Supreme Court today upheld by a 4-1 vote the construction permits of the consortium building the Thirty Meter Telescope (TMT) on Mauna Kea.

In its own press release, the TMT consortium said that it “will move forward with fulfilling the numerous conditions and requirements of [the state’s permit] prior to the start of any construction.”

The comments by one of the the telescope’s opponents at the first link are revealing.

Kealoha Pisciotta, one of the main leaders against the telescope, said she’s doesn’t know what their next steps will be, but she’s not hopeful that more legal wrangling will help. “The court is the last bastion in democracy,” she said. “The only other option is to take to the streets. If we lose the integrity of the court, then you’re losing normal law and order, and the only other option is people have to rise up.” [emphasis mine]

Let me translate: We didn’t get our way, so we’re now going to throw another tantrum! Expect more protests and attempts to block construction. Expect the Hawaiian government, dominated almost entirely by Democrats, to fold to those protests. Expect more delays. For example, do you really think the permit process was really done?

State Department of Land and Natural Resources Chairwoman Suzanne Case said the next steps involve telescope builders submitting construction plans. The department will review the plans before issuing permission to proceed.

This was all done almost a decade earlier, and was exactly what the Supreme Court ruled on. To bring it up now suggests the state government is still quietly looking for loopholes to stop the construction, even though the public supports construction and the protesters are a decided minority.

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NASA officially retires Kepler

12:42 pm

NASA today officially retired Kepler after nine years of operations.

After nine years in deep space collecting data that indicate our sky to be filled with billions of hidden planets – more planets even than stars – NASA’s Kepler space telescope has run out of fuel needed for further science operations. NASA has decided to retire the spacecraft within its current, safe orbit, away from Earth. Kepler leaves a legacy of more than 2,600 planet discoveries from outside our solar system, many of which could be promising places for life.

Exoplanet hunting however does not end here. Unlike Hubble, astronomers and NASA planned ahead for Kepler’s demise, and this year launched TESS to continue its work, in an even more sophisticated manner.

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Fast radio bursts not detected at certain radio wavelengths

8:47 am

In observations by two different radio telescopes operating at different radio wavelengths but looking at the same part of the sky, astronomers have found that an observed fast radio burst was not detected by one of those telescopes.

The Curtin University-led Murchison Widefield Array (MWA) and CSIRO’s Australian SKA Pathfinder (ASKAP) telescopes were searching the sky for fast radio bursts, which are exceptionally bright flashes of energy coming from deep space. These extreme events last for only a millisecond but are so bright that many astronomers initially dismissed the first recorded fast radio burst as an observational error.

In research published in the Astrophysical Journal Letters, astronomers describe how ASKAP detected several extremely bright fast radio bursts, but the MWA—which scans the sky at lower frequencies—did not see anything, even though it was pointed at the same area of sky at the same time.

Lead author Dr Marcin Sokolowski, from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR), said the fact that the fast radio bursts were not observed at lower frequencies was highly significant. “When ASKAP sees these extremely bright events and the MWA doesn’t, that tells us something really unexpected is going on; either fast radio burst sources don’t emit at low frequencies, or the signals are blocked on their way to Earth,” Dr Sokolowski said.

If blocked at these lower frequencies, this tells theorists something about the environment where the burst occurred. If instead the burst does not emit in those lower frequencies, it tells them something about the burst itself.

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Number of candidate exo-Earths reduced by Gaia data

8:32 am

Worlds without end: The number of candidate exo-Earths identified by Kepler has now been reduced based on data from Europe’s Gaia telescope.

To date, NASA’s prolific Kepler space telescope has discovered about 30 roughly Earth-size exoplanets in their host stars’ “habitable zone” — the range of orbital distances at which liquid water can likely exist on a world’s surface.

Or so researchers had thought. New observations by the European Space Agency’s (ESA) Gaia spacecraft suggest that the actual number is probably significantly smaller — perhaps between two and 12, NASA officials said today.

Gaia launched in December of 2013 to create an ultraprecise 3D map of the Milky Way. So far, this map includes position information for about 1.7 billion stars and distance data for about 1.3 billion stars, according to NASA officials. Gaia’s observations suggest that some of the Kepler host stars are brighter and bigger than previously believed, the officials added. Planets orbiting such stars are therefore likely larger and hotter than previously thought.

Being hotter and larger, the habitable zone for these stars shifts outward, placing the exoEarth’s outside the habitable zone.

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Hubble resumes science operations

8:27 am

After three weeks of successful trouble-shooting of a backup gyroscope scientists have now returned the Hubble Space Telescope to full science operations.

Everyone should understand that this situation is now very temporary. Hubble no longer has any backup gyroscopes. If another fails, they will have to go to a one-gyroscope mode, holding the second working gyroscope back as a back-up, in order to extend the telescope’s life as much as possilbe. In that mode the telescope can operate for a significant period, but will have limited capabilities.

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Astronomers confirm Earth has satellite dust clouds

9:05 am

Astronomers have confirmed the existence of two satellite dust clouds at the Earth’s L4 and L5 Lagrange points 250 thousand miles away, first spotted back in the 1960s.

The images they obtained show polarised light reflected from dust, extending well outside the field of view of the camera lens. The observed pattern matches predictions made by the same group of researchers in an earlier paper and is consistent with the earliest observations of the Kordylewski clouds six decades ago. Horváth’s group were able to rule out optical artefacts and other effects, meaning that the presence of the dust cloud is confirmed.

Since these locations are potential space station locations, determining the existence and nature of these dust clouds is important.

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