December 19, 2011

Good Morning,

Bacteria proves once again that when it comes to life, simplicity reins supreme. Scientists have discovered that particular microbes can thrive in Mars-like conditions. Check out the details in the last article.

Until Next Time,
Erin

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Astronomers identify source of supernova

SANTA BARBARA, Calif. - A supernova that exploded in August was a white dwarf star, but its companion could not have been a red giant as previously suspected, U.S. astronomers say. The new "type Ia" thermonuclear supernova exploded Aug. 24 in the Pinwheel galaxy, located in the constellation Ursa Major, also known as the Big Dipper. "It's been nearly 50 years since the original theoretical suggestions were made that these supernovae were caused by white dwarfs," physicist Lars Bildsten of the University of California, Santa Barbara, said in a university release Wednesday. Astrophysicists have discovered type Ia supernovae are part of binary systems, two stars orbiting each other. White dwarf stars are small but very dense stars, and red giants are stars that swell to massive proportions when they approach middle age. A white dwarf results when a star similar in size to our sun reaches the end of its life and normally would be dead forever unless it has a companion star. Then the white dwarf can steal its companion star's matter and come back to life. If it steals too much matter the result can be an explosion as a Type Ia supernova. Scientists are not yet sure of the type of the companion star to the recent white-dwarf-turned supernova but have ruled out the type of star theories had led them to expect, a red giant. "This is the first time through direct imaging of the explosion site, we were able to rule out certain types of stars as the companion to a Type Ia supernova," Weidong Li, a research scientist at the University of California, Berkeley said. "The second star couldn't have been a massive red giant."


Smallest-known black hole observed

GREENBELT, Md. - Astronomers say data from a U.S. X-ray satellite has revealed the "heartbeat" of the smallest-known black hole. The evidence gathered by NASA's Rossi X-ray Timing Explorer is in the form of a specific type of X-ray pattern, nicknamed a "heartbeat" because of its resemblance to an electrocardiogram, a release from the space agency said Thursday. The black hole is part of a binary system with a normal star, and the system is named IGR J17091-3624 after the astronomical coordinates of its sky position. Researchers say the black hole may weigh less than three times the sun's mass, near the theoretical mass boundary where black holes become possible. Based on its X-ray "heartbeat" captured by the RXTE satellite, astronomers say IGR J17091 must possess a minuscule black hole. "Just as the heart rate of a mouse is faster than an elephant's, the heartbeat signals from these black holes scale according to their masses," said Diego Altamirano, an astrophysicist at the University of Amsterdam in the Netherlands. Launched in late 1995, RXTE is second only to Hubble as the longest-serving of NASA's operating astrophysics missions, the space agency said.


Ancient disease mutation identified

COLUMBUS, Ohio - U.S. researchers say they've identified the second-oldest human disease mutation yet discovered, dating back to 11,600 B.C. Researchers at Ohio State University estimate the mutation, which causes a rare, inherited vitamin B12 deficiency called Imerslund-Grasbeck syndrome, arose in the Middle East some 13,600 years ago. Only a mutation seen in cystic fibrosis that arose between 11,000 and 52,000 years ago is believed to be older, a university release said Thursday. The mutation is found mostly in people of Arabic, Turkish and Jewish ancestry, researchers said. "Our findings permit reliable genetic diagnostics in suspected cases of IGS in that this mutation should be considered first when genetically screening patients from these populations," OSU researcher Stephan M. Tanner said. Although the mutation is found in different ethnic populations, it originated in a single, prehistoric individual and was passed down to that individual's descendants, researchers said. This is unusual, they said, because such "founder mutations" usually are restricted to specific ethnic groups or relatively isolated populations.


Bacteria can live in Mars-like conditions

CORVALLIS, Ore. - Microbes found in a lava tube in Oregon are thriving in Mars-like conditions -- near freezing temperatures and low levels of oxygen, U.S. researchers say. Oregon State University researchers say the microbes can grow in the absence of organic food, with their metabolism driven by the oxidation of iron from olivine, a common volcanic mineral. These factors make the microbes capable of living in the subsurface of Mars and other planetary bodies, the scientists say. "This microbe is from one of the most common genera of bacteria on Earth," OSU doctoral student Amy Smith said in a university release Thursday. "You can find its cousins in caves, on your skin, at the bottom of the ocean and just about anywhere. What is different, in this case, is its unique qualities that allow it to grow in Mars-like conditions." The microbes were collected from a lava tube near Newberry Crater in Oregon's Cascades Mountains at an elevation of about 5,000 feet. "We know from direct examination, as well as satellite imagery, that olivine is in Martian rocks," study author Martin Fisk said. "And now we know that olivine can sustain microbial life. "Although this study does not exactly duplicate what you would find on Mars, it does show that bacteria can live in similar conditions," he said.

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