Fingerprint From a First-Generation Star?

by Shannon Hall on August 27, 2014

SDSS001820.5-093939.2 (seen in white) is a small, second-generation star bearing the chemical imprint of one of the universe's first stars.  It shines at an apparent magnitude of 15.8, just south of the celestial equator in the constellation Cetus. Credit: SDSS / NAO

SDSS001820.5-093939.2 (seen in white) is a small, second-generation star bearing the chemical imprint of one of the universe’s first stars. It shines at an apparent magnitude of 15.8, just south of the celestial equator in the constellation Cetus. Credit: SDSS / NAO

The young universe was composed of a pristine mix of hydrogen, helium, and a tiny trace of lithium. But after hundreds of millions of years, it began to cool and giant clouds of the primordial elements collapsed to form the first stars.

The first “Population III” stars were extremely massive and bright, synthesizing the first batches of heavy elements, and erupting as supernovae after relatively short lifetimes of just a few million years. This cycle of star birth and death has steadily produced and dispersed more heavy elements throughout cosmic history.

Astronomers haven’t spotted any of the first stars still shining today. But now, a team using the 8.2-meter Subaru Telescope has discovered an ancient low-mass star that likely formed from the elements produced in the supernova explosion of a very massive first generation star.

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The Atacama Large Millimeter/submillimeter Array (ALMA) and many other telescopes on the ground and in space have been used to obtain the best view yet of a collision that took place between two galaxies when the Universe was only half its current age. The astronomers enlisted the help of a galaxy-sized magnifying glass to reveal otherwise invisible detail. These new studies of the galaxy H-ATLAS J142935.3-002836 have shown that this complex and distant object looks surprisingly like the well-known local galaxy collision, the Antennae Galaxies. In this picture you can see the foreground galaxy that is doing the lensing, which resembles how our home galaxy, the Milky Way, would appear if seen edge-on. But around this galaxy there is an almost complete ring — the smeared out image of a star-forming galaxy merger far beyond. This picture combines the views from the NASA/ESA Hubble Space Telescope and the Keck-II telescope on Hawaii (using adaptive optics). Credit: ESO/NASA/ESA/W. M. Keck Observatory

This image combines the views from the Hubble Space Telescope and the Keck-II observatory to show a foreground galaxy (a spiral galaxy viewed edge-on) and an almost complete ring: the smeared out image of a star-forming merger beyond. Credit: ESO / NASA / ESA / W. M. Keck Observatory

An international team of astronomers has obtained the best view yet of two galaxies colliding when the universe was only half its current age.

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The Rosetta navigation camera sent back this image of Comet 67P/Churyumov-Gerasimenko on August 23, showing about a quarter of the four-kilometer (2.5-mile) comet. This image was acquired from a distance of 61 kilometers (38 miles). Credit: ESA/Rosetta/NAVCAM

The Rosetta navigation camera sent back this image of Comet 67P/Churyumov-Gerasimenko on Aug. 23, showing about a quarter of the four-kilometer (2.5-mile) comet. This image was acquired from a distance of 61 kilometers (38 miles). Credit: ESA/Rosetta/NAVCAM

Wow! Rosetta is getting ever-closer to its target comet by the day. This navigation camera shot from Aug. 23 shows that the spacecraft is so close to Comet 67P/Churyumov-Gerasimenko that it’s difficult to fit the entire 2.5-mile (four-kilometer) comet in a single frame.

As the European Space Agency explained, the way that Rosetta is taking pictures is changing — and that’s not only because the spacecraft is searching for a safe touchdown site for its lander, Philae.

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Eta Carinae, one of the most massive stars known. Image credit: NASA

Eta Carinae, one of the most massive stars known. Image credit: NASA

While the stars appear unchanging when you take a quick look at the night sky, there is so much variability out there that astronomers will be busy forever. One prominent example is Eta Carinae, a star system that erupted in the 19th century for about 20 years, becoming one of the brightest stars you could see in the night sky. It’s so volatile that it’s a high candidate for a supernova.

The two stars came again to their closest approach this month, under the watchful eye of the Chandra X-Ray Observatory. The observations are to figure out a puzzling dip in X-ray emissions from Eta Carinae that happen during every close encounter, including one observed in 2009.

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Expedition 36/37 astronaut Karen Nyberg uses a fundoscope to take still and video images of her eye while in orbit. Credit: NASA

Expedition 36/37 astronaut Karen Nyberg uses a fundoscope to take still and video images of her eye while in orbit. Credit: NASA

How does microgravity affect your health? One of the chief concerns of NASA astronauts these days is changes to eyesight. Some people come back from long-duration stays in space with what appears to be permanent changes, such as requiring glasses when previously they did not.

And the numbers are interesting. A few months after NASA told Universe Today that 20% of astronauts may face this problem, a new study points out that 21 U.S. astronauts that have flown on the International Space Station for long flights (which tend to be five to six months) face visual problems.

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