Archive for June, 2013

Texas Astronomers Discover Pulsations In Crystalized, Dying Star

Astronomers from The University of Texas at Austin and colleagues have used the 2.1-meter Otto Struve Telescope at the university’s McDonald Observatory to discover pulsations from the crystalized remnant of a burnt-out star. The finding will allow astronomers to see below the star’s atmosphere and into its interior, much like earthquakes allow geologists to study compositions below Earth’s surface. The findings appear in the current issue of The Astrophysical Journal Letters.

The Texas astronomers made their discovery in collaboration with astronomers from Brazil’s Universidade Federal do Rio Grande do Sul, the University of Oklahoma, and the Smithsonian Astrophysical Observatory.

The star, GD 518, is roughly 170 light years from Earth in the constellation Draco, but far too faint to be seen without a telescope. It is a white dwarf, a star at the end of its life cycle that is essentially just a burnt-out core, the ashy byproduct of previous epochs of nuclear fusion.

The star is unique in that much of it is likely suspended in a state more akin to a solid than a liquid or gas. The interiors of dying stars can become crystalized similar to the way in which frigid water freezes into ice, like the slow formation of glaciers in cooling ocean water.

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Hubble Spots Galaxies In Close Encounter

Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

The NASA/ESA Hubble Space Telescope has produced this vivid image of a pair of interacting galaxies known as Arp 142. When two galaxies stray too close to each other they begin to interact, causing spectacular changes in both objects. In some cases the two can merge — but in others, they are ripped apart.

Just below the centre of this image is the blue, twisted form of galaxy NGC 2936, one of the two interacting galaxies that form Arp 142 in the constellation of Hydra. Nicknamed “the Penguin” or “the Porpoise” by amateur astronomers, NGC 2936 used to be a standard spiral galaxy before being torn apart by the gravity of its cosmic companion.

The remnants of its spiral structure can still be seen — the former galactic bulge now forms the “eye” of the penguin, around which it is still possible to see where the galaxy’s pinwheeling arms once were. These disrupted arms now shape the cosmic bird’s “body” as bright streaks of blue and red across the image. These streaks arch down towards NGC 2936’s nearby companion, the elliptical galaxy NGC 2937, visible here as a bright white oval. The pair show an uncanny resemblance to a penguin safeguarding its egg.

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Super-Hurricane-Force Winds On Venus Are Getting Stronger

June 18, 2013 1 comment

Venus cloud tops. Credit: ESA/MPS/DLR/IDA

Venus cloud tops. Credit: ESA/MPS/DLR/IDA

As the closest planet to Earth, Venus is a relatively easy object to observe. However, many mysteries remain, not least the super-rotation of Venus’ atmosphere, which enables high altitude winds to circle the planet in only four days. Now images of cloud features sent back by ESA’s Venus Express orbiter have revealed that these remarkably rapid winds are becoming even faster.

Similar in size to Earth, Venus has an extremely dense, carbon-dioxide-rich atmosphere and the planet’s surface is completely hidden by a blanket of bland, yellowish cloud. Only at ultraviolet wavelengths (and to a lesser extent in the infrared) do striking cloud streaks and individual cells emerge, due to the presence of some unknown UV absorber in the cloud deck.

By tracking the movements of these distinct cloud features, observers have been able to measure the super-hurricane-force winds that sweep around the planet at the cloud tops, some 70 km above the scorching volcanic plains.

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Sunny Super-Earth?

A research team led by Akihiko Fukui (NAOJ), Norio Narita (NAOJ) and Kenji Kuroda (the University of Tokyo) observed the atmosphere of super-Earth “GJ3470b” in Cancer for the first time in the world using two telescopes at OAO (Okayama Astrophysical Observatory, NAOJ). This super-Earth is an exoplanet, having only about 14 times the mass of our home planet, and it is the second lightest one among already-surveyed exoplanets. The observational data revealed that this planet is highly likely to NOT be covered by thick clouds.

The researchers expect that future detection of the specific composition of the planet’s atmosphere based on highly accurate observations with larger aperture telescopes, such as the Subaru Telescope. This planet orbits around its primary star very closely at a rapid rate. We don’t yet understand the formation process of such planets. If future detailed observations of the atmosphere detect any substance that becomes ice at low temperatures, it probably means that this planet was originally formed at a distance (a few astronomical units) from the primary star, where ice could exist, and moved toward the primary star thereafter. In contrast, if such a substance cannot be found in the atmosphere, this planet was quite likely formed at its present location (near the primary star) from its early stage. Thus, it is expected that the detailed observations of the atmosphere of GJ3470b can begin to reveal the mysteries behind the formation of super-Earths.

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Mars Water-Ice Clouds Are Key To Odd Thermal Rhythm

Researchers using NASA’s Mars Reconnaissance Orbiter have found that temperatures in the Martian atmosphere regularly rise and fall not just once each day, but twice.

“We see a temperature maximum in the middle of the day, but we also see a temperature maximum a little after midnight,” said Armin Kleinboehl of NASA’s Jet Propulsion Laboratory in Pasadena, Calif., who is the lead author of a new report on these findings.

Temperatures swing by as much as 58 degrees Fahrenheit (32 kelvins) in this odd, twice-a-day pattern, as detected by the orbiter’s Mars Climate Sounder instrument.

The new set of Mars Climate Sounder observations sampled a range of times of day and night all over Mars. The observations found that the pattern is dominant globally and year-round. The report is being published in the journal Geophysical Research Letters.

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The University Of Alicante Finds The First Evidence Of A New Phase In Neutron Stars

A study led by the University of Alicante, in which in the National Research Council (CSIC) has participated, has detected what may be the first observational evidence of existence of a new exotic phase of matter in the inner crust of neutron stars (pulsars).

The latest issue of Nature Physics shows the results of a research project that addresses one of the unknowns in the field of X-ray pulsars, the existence of a limit higher than 12 seconds in the rotation periods of isolated neutron stars. This limit is actually due to the existence of new exotic phases of matter. Pulsars are neutron stars (ultracompact and strongly magnetized stars) in rotation, which emit electromagnetic radiation with amazing precision in their periodicity.

As José A. Pons says, lecturer at the University of Alicante’s Relativistic Astrophysics Group and Director of the Department of Applied Physics, who led the work: “This may be the first observational evidence of existence of the phase of nuclear ‘pasta’ inside neutron stars, which may allow that future missions of X-ray observatories can be used to define aspects of how nuclear interaction works, which is not yet entirely clear”.

Nuclear Pasta, named for its resemblance to the Italian pasta, occurs when the combination of nuclear and electromagnetic forces, at densities close to the atomic nuclei, favours the ordering of the nucleons (protons and neutrons) in non-spherical shapes , as sheets or filaments (lasagna or spaghetti).

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The Flare Star WX UMa Becomes 15 Times Brighter In Less Than 3 Minutes

A flare star. Credit: Casey Reed/NASA

A flare star. Credit: Casey Reed/NASA

Astrophysicists at the University of Santiago de Compostela (Spain) and the Byurakan Observatory (Armenia) have detected a star of low luminosity which within a matter of moments gave off a flare so strong that it became almost 15 times brighter. The star in question is the flare star WX UMa.

“We recorded a strong flare of the star WX UMa, which became almost 15 times brighter in a matter of 160 seconds,” explains to SINC the astrophysicist Vakhtang Tamazian, professor at the University of Santiago de Compostela. The finding has been published in the Astrophysics journal.

This star is in the Ursa Major constellation, around 15.6 light years from the Earth, and it forms part of a binary system. Its companion shines almost 100 times brighter, except at times such as that observed, in which the WX UMa gives off its flares. This can happen several times a year, but not as strongly as that which was recorded in this instance.

Dr Tamazian and other researchers detected this exceptional brightness from the Byurakan Observatory in Armenia. “Furthermore, during this period of less than three minutes the star underwent an abrupt change from spectral type M to B; in other words, it went from a temperature of 2,800 kelvin (K) to six or seven times more than that.”

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NASA-Led Study Explains Decades Of Black Hole Observations

A new study by astronomers at NASA, Johns Hopkins University and the Rochester Institute of Technology confirms long-held suspicions about how stellar-mass black holes produce their highest-energy light.

“Our work traces the complex motions, particle interactions and turbulent magnetic fields in billion-degree gas on the threshold of a black hole, one of the most extreme physical environments in the universe,” said lead researcher Jeremy Schnittman, an astrophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Md.

By analyzing a supercomputer simulation of gas flowing into a black hole, the team finds they can reproduce a range of important X-ray features long observed in active black holes.

Gas falling toward a black hole initially orbits around it and then accumulates into a flattened disk. The gas stored in this disk gradually spirals inward and becomes greatly compressed and heated as it nears the center. Ultimately reaching temperatures up to 20 million degrees Fahrenheit (12 million C) — some 2,000 times hotter than the sun’s surface — the gas shines brightly in low-energy, or soft, X-rays.

For more than 40 years, however, observations have shown that black holes also produce considerable amounts of “hard” X-rays, light with energy tens to hundreds of times greater than soft X-rays. This higher-energy light implies the presence of correspondingly hotter gas, with temperatures reaching billions of degrees.

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Hubble Uncovers Evidence For Extrasolar Planet Under Construction

Nearly 900 extrasolar planets have been confirmed to date, but now for the first time astronomers think they are seeing compelling evidence for a planet under construction in an unlikely place, at a great distance from its diminutive red dwarf star.

The keen vision of NASA’s Hubble Space Telescope has detected a mysterious gap in a vast protoplanetary disk of gas and dust swirling around the nearby star TW Hydrae, located 176 light-years away in the constellation Hydra (the Sea Serpent). The gap’s presence is best explained as due to the effects of a growing, unseen planet that is gravitationally sweeping up material and carving out a lane in the disk, like a snow plow.

Researchers, led by John Debes of the Space Telescope Science Institute in Baltimore, Md., found the gap about 7.5 billion miles from the red dwarf star. If the putative planet orbited in our solar system, it would be roughly twice Pluto’s distance from the Sun.

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NASA’s Chandra Turns Up Black Hole Bonanza In Galaxy Next Door

 Andromeda. Image Credit: X-ray: NASA/CXC/SAO/R. Barnard, Z. Lee et al.; Optical: NOAO/AURA/NSF/REU Program/B. Schoening, V. Harvey and Descubre Foundation/CAHA/OAUV/DSA/V. Peris

Andromeda. Image Credit: X-ray: NASA/CXC/SAO/R. Barnard, Z. Lee et al.; Optical: NOAO/AURA/NSF/REU Program/B. Schoening, V. Harvey and Descubre Foundation/CAHA/OAUV/DSA/V. Peris

Using more than 150 Chandra observations, spread over 13 years, researchers identified 26 black hole candidates, the largest number to date, in a galaxy outside our own. Many consider Andromeda to be a sister galaxy to the Milky Way. The two ultimately will collide, several billion years from now.

“While we are excited to find so many black holes in Andromeda, we think it’s just the tip of the iceberg,” said Robin Barnard of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and lead author of a new paper describing these results. “Most black holes won’t have close companions and will be invisible to us.”

The black hole candidates belong to the stellar mass category, meaning they formed in the death throes of very massive stars and typically have masses five to 10 times that of our sun. Astronomers can detect these otherwise invisible objects as material is pulled from a companion star and heated up to produce radiation before it disappears into the black hole.

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