Archive for March 12, 2013

NASA Helps See Buried Mars Flood Channels In 3-D

NASA’s Mars Reconnaissance Orbiter has provided images allowing scientists for the first time to create a 3-D reconstruction of ancient water channels below the Martian surface.

The spacecraft took numerous images during the past few years that showed channels attributed to catastrophic flooding in the last 500 million years. During this period, Mars had been otherwise considered cold and dry. These channels are essential to understanding the extent to which recent hydrologic activity prevailed during such arid conditions. They also help scientists determine whether the floods could have induced episodes of climate change.

“Our findings show the scale of erosion that created the channels previously was underestimated and the channel depth was at least twice that of previous approximations,” said Gareth Morgan, a geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies in Washington and lead author on the paper. “This work demonstrates the importance of orbital sounding radar in understanding how water has shaped the surface of Mars.”

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Pan-STARRS Finds A “Lost” Supernova

March 12, 2013 1 comment

The star Eta Carinae is ready to blow. 170 years ago, this 100-solar-mass object belched out several suns’ worth of gas in an eruption that made it the second-brightest star after Sirius. That was just a precursor to the main event, since it will eventually go supernova.

Supernova explosions of massive stars are common in spiral galaxies like the Milky Way, where new stars are forming all the time. They are almost never seen in elliptical galaxies where star formation has nearly ceased. As a result, astronomers were surprised to find a young-looking supernova in an old galaxy. Supernova PS1-12sk, discovered with the Pan-STARRS telescope on Haleakala, is rare in more ways than one.

“This supernova is one-of-a-kind,” said Nathan Sanders of the Harvard-Smithsonian Center for Astrophysics (CfA), lead author of the discovery paper. “And it’s definitely in the wrong neighborhood.”

Based on the presence of helium and other features, PS1-12sk is classified as a very rare Type Ibn supernova – only the sixth such example found out of thousands of supernovae. Although the origin of this supernova type is unclear, the most likely cause seems to be the explosion of a massive star that previously ejected massive amounts of helium gas, much like Eta Carinae’s Homunculus Nebula.

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Hubble Finds Birth Certificate Of Oldest Known Star

A team of astronomers using NASA’s Hubble Space Telescope has taken an important step closer to finding the birth certificate of a star that’s been around for a very long time. “We have found that this is the oldest known star with a well-determined age,” said Howard Bond of Pennsylvania State University in University Park, Pa., and the Space Telescope Science Institute in Baltimore, Md.

The star could be as old as 14.5 billion years (plus or minus 0.8 billion years), which at first glance would make it older than the universe’s calculated age of about 13.8 billion years, an obvious dilemma. But earlier estimates from observations dating back to 2000 placed the star as old as 16 billion years. And this age range presented a potential dilemma for cosmologists. “Maybe the cosmology is wrong, stellar physics is wrong, or the star’s distance is wrong,” Bond said. “So we set out to refine the distance.”

The new Hubble age estimates reduce the range of measurement uncertainty, so that the star’s age overlaps with the universe’s age — as independently determined by the rate of expansion of space, an analysis of the microwave background from the big bang, and measurements of radioactive decay.

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