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Archive for April 5, 2013

A Meteorite Mystery: First Meteorite From Mercury Found?


Image Credit: Stefan Ralew

Image Credit: Stefan Ralew

Could this stone be the first meteorite from Mercury ever found? WUSTL’s meteorite expert sifts the evidence.

Early in 2012, someone in Southern Morocco picked up 35 greenish stones, including the one shown. Purchased by a dealer in Erfoud, Morocco, it was then resold to Stefan Ralew, a meteorite collector from Berlin.

The dealer was demanding a high price, and Ralew may have hesitated. But the wrinkled glassy coating on one face of the rock was clearly a fusion crust, a kind of glaze that forms when a meteorite is heated as it passes through the atmosphere.

Looking at other faces he would have recognized it as a type of meteorite called an achondrite, says Randy Korotev, WUSTL’s meteorite expert. That meant it was an exceptional stone.

Full Story: http://news.wustl.edu/news/Pages/25222.aspx

Observationally Confirmed Supernova Explosion Of A Yellow Supergiant Star


Credit: Conrad Jung

Credit: Conrad Jung

Observational results of the Hubble Space Telescope announced in March 2013 confirmed the theoretical prediction by the Bersten team at the Kavli Institute for the Physics and Mathematics of the Universe that the yellow supergiant star found at the location of supernova SN 2011dh in the famous nearby galaxy M51 was indeed the star that exploded.

The nature of the progenitor star (or progenitor system) of core-collapse supernovae and the origin of their diversity are important open questions in the field of astrophysics. It has been believed that most massive stars explode when they become red supergiants, or, alternatively, blue compact stars (the so-called Wolf-Rayet stars).

The supernova SN 2011dh that appeared in the M51 galaxy (Figure 1) revealed a different story. Two groups of astronomers independently detected a yellow supergiant (YSG) star at a location closely matching that of the supernova in archival images obtained with the Hubble Space Telescope (HST) before the supernova explosion. A question then arose as to how such a star could undergo a supernova explosion. The YSG phase is an intermediate, short-lived stage in the evolutionary models of single stars, during which no supernova explosions are expected to occur.

Full Story: http://www.ipmu.jp/node/1537

Mapping The Chemistry Needed For Life At Europa


A new paper led by a NASA researcher shows that hydrogen peroxide is abundant across much of the surface of Jupiter’s moon Europa. The authors argue that if the peroxide on the surface of Europa mixes into the ocean below, it could be an important energy supply for simple forms of life, if life were to exist there. The paper was published online recently in the Astrophysical Journal Letters.

“Life as we know it needs liquid water, elements like carbon, nitrogen, phosphorus and sulfur, and it needs some form of chemical or light energy to get the business of life done,” said Kevin Hand, the paper’s lead author, based at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Europa has the liquid water and elements, and we think that compounds like peroxide might be an important part of the energy requirement. The availability of oxidants like peroxide on Earth was a critical part of the rise of complex, multicellular life.”

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-126

Scientists To Io: Your Volcanoes Are In The Wrong Place


Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Jupiter’s moon Io is the most volcanically active world in the Solar System, with hundreds of volcanoes, some erupting lava fountains up to 250 miles high. However, concentrations of volcanic activity are significantly displaced from where they are expected to be based on models that predict how the moon’s interior is heated, according to NASA and European Space Agency researchers.

Io is caught in a tug-of-war between Jupiter’s massive gravity and the smaller but precisely timed pulls from two neighboring moons that orbit further from Jupiter – Europa and Ganymede. Io orbits faster than these other moons, completing two orbits every time Europa finishes one, and four orbits for each one Ganymede makes. This regular timing means that Io feels the strongest gravitational pull from its neighboring moons in the same orbital location, which distorts Io’s orbit into an oval shape. This in turn causes Io to flex as it moves around Jupiter.

The question remains regarding exactly how this tidal heating affects the moon’s interior. Some propose it heats up the deep interior, but the prevailing view is that most of the heating occurs within a relatively shallow layer under the crust, called the asthenosphere. The asthenosphere is where rock behaves like putty, slowly deforming under heat and pressure.

Full Story: http://www.nasa.gov/topics/solarsystem/features/io-volcanoes-displaced.html

ALMA Detects Signs Of Star Formation Surprisingly Close To Galaxy’s Supermassive Black Hole


Credit: Yusef-Zadeh et al., ALMA (ESO, NAOJ, NRAO), NRAO/AUI/NSF

Credit: Yusef-Zadeh et al., ALMA (ESO, NAOJ, NRAO), NRAO/AUI/NSF

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered signs of star formation perilously close to the supermassive black hole at the center of the Milky Way Galaxy. If confirmed, this would be the first time that star formation was observed so close to the galactic center.

The center of our galaxy, 27,000 light-years away in the direction of the constellation Sagittarius, is home to a monstrous black hole with a mass of four million suns. Extending outward from this gravitational behemoth for many light-years is a turbulent region of space that is thought to be wracked by such extreme tidal forces that any star-forming clouds of dust and gas would be stretched thin and shredded long before infant stars could emerge.

Yet against these extreme odds, ALMA spotted telltale jets of material bursting out of what appear to be dense cocoons of gas and dust. These jets, if they were observed in more placid surroundings, would indicate the formation of a young star. The results were accepted for publication in the Astrophysical Journal Letters.

Full Story: http://www.nrao.edu/pr/2013/protostar/

Gravity-Bending Find Leads To Kepler Meeting Einstein


Artist's concept. Image credit: NASA/JPL-Caltech

Artist’s concept. Image credit: NASA/JPL-Caltech

NASA’s Kepler space telescope has witnessed the effects of a dead star bending the light of its companion star. The findings are among the first detections of this phenomenon — a result of Einstein’s general theory of relativity — in binary, or double, star systems.

The dead star, called a white dwarf, is the burnt-out core of what used to be a star like our sun. It is locked in an orbiting dance with its partner, a small “red dwarf” star. While the tiny white dwarf is physically smaller than the red dwarf, it is more massive.

“This white dwarf is about the size of Earth but has the mass of the sun,” said Phil Muirhead of the California Institute of Technology, Pasadena, lead author of the findings to be published April 20 in the Astrophysical Journal. “It’s so hefty that the red dwarf, though larger in physical size, is circling around the white dwarf.”

Muirhead and his colleagues regularly use public Kepler data to search for and confirm planets around smaller stars, the red dwarfs, also known as M dwarfs. “We saw what appeared to be huge dips in the light from the star, and suspected it was from a giant planet, roughly the size of Jupiter, passing in front,” said Muirhead.

Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-124