Tag: astronomy

Astronomers take best image of Betelgeuse yet

5:21 pm

Betelqeuse

Using the Atacama Large Millimeter/submillimeter Array Telescope (ALMA), astronomers have produced the best picture of the red giant star Betelgeuse taken so far.

Using ESO’s Very Large Telescope astronomers discovered a vast plume of gas almost as large as our Solar System. Astronomers have also found a gigantic bubble that boils away on Betelgeuse’s surface. These features help to explain how the star is shedding gas and dust at tremendous rates (eso0927, eso1121). In this picture, ALMA observes the hot gas of the lower chromosphere of Betelgeuse at sub-millimeter wavelengths — where localised increased temperatures explain why it is not symmetric.

The image on the right is that image, slightly reduced to post here. The bulge on the star’s left illustrates the unevenness of the star’s upper atmosphere. I suspect that continuous observations would reveal the outer atmosphere waxing and waning almost like the stuff inside a lava lamp.

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Astronomers discover complex molecules in protostar accretion disk

10:18 am

Astronomers have discovered several complex molecules in the accretion disk surrounding a very young baby star about 1300 light years away in the constellation Orion.

The research team’s ALMA observations have clearly detected an atmosphere of complex organic molecules above and below the disk. These include methanol (CH3OH), deuterated methanol (CH2DOH), methanethiol (CH3SH), and formamide (NH2CHO). These molecules have been proposed to be the precursors for producing biomolecules such as amino acids and sugars. “They are likely formed on icy grains in the disk and then released into the gas phase because of heating from stellar radiation or some other means, such as shocks,” says co-author Zhi-Yun Li of the University of Virginia.

What is even most interesting about this discovery is that these complex molecules are not scattered throughout the disk, but are concentrated in regions above and below its central plane, what the astronomers are labeling “an atmosphere.” This suggests that differentiation — the same process that separates the heavier molecules from lighter ones both in centrifuges and in the cores of planets — occurs quickly in accretion disks as well.

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Uranus’s magnetic field switches on and off daily

9:54 am

Using data from the Voyager 2 flyby of Uranus in 1986, scientists now think that the gas giant’s magnetic field switches on and off each day as the planet rotates.

Uranus’s magnetosphere, in contrast [to Earth], exhibits precise regularity in its mode changes. This, say the researchers, is because it lies at an angle of roughly 60 degrees to the planet’s spin axis, causing its interaction with incoming solar winds to vary dramatically during the 17 hours it takes for a full rotation. “Uranus is a geometric nightmare,” says Paty.

“The magnetic field tumbles very fast, like a child cartwheeling down a hill head over heels. When the magnetised solar wind meets this tumbling field in the right way, it can reconnect and Uranus’s magnetosphere goes from open to closed to open on a daily basis.”

The researchers suggest the robust and regular changes to the magnetosphere may mean that the icy planet has spectacular auroras across its breadth every day.

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Orbital motion of a binary black hole detected for the first time

10:19 am

Astronomers have for the first time measured the orbital motion of two supermassive black holes that orbit each other.

Based on the initial data, the two black holes appear to orbit each other every 30,000 years. Eventually, they will spiral into each other, merge, and in the process produce ripples in the surrounding gravitational field that will be detectable by future gravitational wave detectors.

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Update of Kepler exoplanet catalog

9:44 am

Worlds without end: The Kepler science team has released an update of the space telescope’s exoplanet candidate list, adding 219 new exoplanet candidates.

NASA’s Kepler space telescope team has released a mission catalog of planet candidates that introduces 219 new planet candidates, 10 of which are near-Earth size and orbiting in their star’s habitable zone, which is the range of distance from a star where liquid water could pool on the surface of a rocky planet. This is the most comprehensive and detailed catalog release of candidate exoplanets, which are planets outside our solar system, from Kepler’s first four years of data. It’s also the final catalog from the spacecraft’s view of the patch of sky in the Cygnus constellation.

With the release of this catalog, derived from data publicly available on the NASA Exoplanet Archive, there are now 4,034 planet candidates identified by Kepler. Of which, 2,335 have been verified as exoplanets. Of roughly 50 near-Earth size habitable zone candidates detected by Kepler, more than 30 have been verified.

Additionally, results using Kepler data suggest two distinct size groupings of small planets. Both results have significant implications for the search for life. The final Kepler catalog will serve as the foundation for more study to determine the prevalence and demographics of planets in the galaxy, while the discovery of the two distinct planetary populations shows that about half the planets we know of in the galaxy either have no surface, or lie beneath a deep, crushing atmosphere – an environment unlikely to host life.

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China launches X-ray space telescope

9:35 am

China today launched the Hard X-ray Modulation Telescope (HXMT), also dubbed Insight by Chinese news sources.

The HXMT carries three x-ray telescopes observing at energies ranging from 20 to 200 kilo-electron volts as well as an instrument to monitor the space environment, according to its designers. While orbiting 550 kilometers above the planet, the HXMT will perform an all-sky survey that is expected to discover a thousand new x-ray sources. Over an expected operating lifetime of 4 years, it will also conduct focused observations of black holes, neutron stars, and gamma ray bursts.

More here. This is China’s first home-grown X-ray space telescope, and its launch once again illustrates that, for at least the next few decades, China intends to be a major player in the exploration of the solar system.

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Design questions might delay construction of China’s first big optical telescope

9:03 am

A disagreement over the design of what China hopes would be, for a short while, the world’s largest optical telescope might delay that telescope’s construction.

On one side is an established engineering team, led by a veteran optics expert responsible for the nation’s largest existing telescope, that is eager to push ahead with an ambitious design. On the other are astronomers reveling in a grassroots priority-setting exercise—unprecedented for China—who have doubts about the ambitious design and favor something simpler.

Now, a panel of international experts has reviewed the designs and come out squarely in favor of the simpler proposal, according to a copy of the review obtained by Science. But the conclusion has not ended what one Chinese astronomer calls “an epic battle” between the high-ranking engineers accustomed to top-down control over projects and the nascent grassroots movement.

The telescope would have a mirror diameter of 12-meters, topping the 10.4 meter Gran Telescopio Canarias in the Canary Islands. To get it built in time to be the largest, they need to approve the construction plan by 2018.

The story is interesting in that is highlights the technical problems that exist for these large telescopes, most of which have had serious engineering issues that have limited their scientific output. The disagreement here is caused by an effort by some Chinese scientists to avoid these problems by using a simpler design.

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Astronomers confirm that comet caused Wow! signal, not aliens

9:01 am

Astronomers have confirmed that the Wow! signal, thought to be the most promising detection by SETI of alien life, was actually caused by a comet.

Last year, a group of researchers from the Center of Planetary Science proposed a new hypothesis that argued a comet might be the culprit. The frequency could be caused by the hydrogen cloud they carry, and the fact that they move accounts for why it seemingly disappeared. Two comets, named 266/P Christensen and P/2008 Y2 (Gibbs), happened to be transiting through that region of space when the Wow! signal was detected, but they weren’t discovered until after 2006.

To test the hypothesis, the team made 200 radio spectrum observations between November 2016 and February 2017. Sure enough, 266/P Christensen was found to emit radio waves at a frequency of 1,420 MHz, and to double check, the researchers moved their radio telescope by one degree. As expected, the signal vanished, and only returned when the telescope was trained back on the comet.

This story demonstrates once again why, in science, it is very dangerous to jump to any conclusions. The data we receive is a mystery. We must keep an open mind to solve that mystery.

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Jupiter gets two more moons

4:51 pm

Astronomers using ground-based telescopes have identified two more moon circling Jupiter, bringing its total now to 69.

Both of these discoveries, as with the vast majority of Jupiter’s moons, occupy retrograde orbits, with inclinations greater than 90°, meaning that they move in directions opposite that of the planet’s spin. These distant, irregular orbits imply that these bodies formed elsewhere in the outer solar system and were captured while passing by early in the planet’s history.

A number of the moons recently discovered have since been lost because their orbits were too poorly constrained. However, some of these lost moons have also be recovered.

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Exoplanet hotter than some stars

1:50 pm

Astronomers have identified an Jupiter-sized exoplanet with a surface that is apparently hotter than the surfaces of some stars.

With a day-side temperature of 4,600 Kelvin (more than 7,800 degrees Fahrenheit), planet KELT-9b is hotter than most stars, and only 1,200 Kelvin (about 2,000 degrees Fahrenheit) cooler than our own sun…. For instance, it’s a gas giant 2.8 times more massive than Jupiter but only half as dense, because the extreme radiation from its host star has caused its atmosphere to puff up like a balloon. And because it is tidally locked to its star—as the Moon is to Earth—the day side of the planet is perpetually bombarded by stellar radiation, and as a result is so hot that molecules such as water, carbon dioxide, and methane can’t form there. The properties of the night side are still mysterious—molecules may be able to form there, but probably only temporarily.

The most interesting aspect of this discovery is that it was done with small, inexpensive ground-based telescopes.

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More near Earth objects found by WISE

12:05 pm

NASA’s Wide-Field Infrared Explorer (WISE) has released its third year of survey data, including the discovery of 97 previously unknown objects.

Of those, 28 were near-Earth objects, 64 were main belt asteroids and five were comets. The spacecraft has now characterized a total of 693 near-Earth objects since the mission was re-started in December 2013.

For reasons that baffle me, NASA added “Near-Earth Object” to the telescope’s name when they restarted the mission, making its official name now NEOWISE.

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LIGO detects its third gravitational wave

8:22 am

LIGO scientists today revealed that the detector had spotted its third gravitational wave in January.

Researchers estimate that the bodies in the latest collision were slightly lighter than those in the first event: one had the mass of 31 Suns and the other 19. (The black holes in the second discovery were even more lightweight, at 14 and 8 solar masses.) But the latest merger is the most distant detected so far. The gravitational waves it produced took somewhere between 1.6 billion and 4.3 billion years to reach Earth — most probably around 2.8 billion years.

This new field of astronomy should get even more interesting in the next year or two, as new detectors come on line in Italy and Japan.

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