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Post Info TOPIC: Galaxy star streams
Blobrana


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Using NASA's Spitzer Space Telescope, an international team of astronomers has discovered streams of young stars flowing from their natal cocoons in distant galaxies. These distant rivers of stars provide an answer to one of astronomy's most fundamental puzzles: how do young stars that form clustered together in dense clouds of dust and gas disperse to form the large, smooth distribution seen in the disks of spiral galaxies like the Milky Way?

"When you look at the disks of galaxies in the infrared they are remarkably smooth. All of the older stars are evenly distributed. But stars aren't born that way; they're born in clusters and associations like the Pleiades cluster, or the association of young stars in the Orion constellation of our own Milky Way galaxy. So the question is - why are the disks of galaxies so smooth?" - team leader David Block of the University of the Wi****ersrand in South Africa.

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Blobrana


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The last remnants of a dwarf galaxy circle the spiral galaxy that tore it apart. Two rivers of starsand possibly dark matterare all that remain of the low-mass dwarf after it was unravelled by the gravity of the much larger spiral, NGC 5907. Astronomers have noted that such streams of stars are relatively common in the outer regions of spiral galaxies, a phenomenon that has been observed on the outskirts of the Milky Way as well as around the nearby Andromeda galaxy.

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Blobrana


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An international team of astronomers has identified huge star streams in the outskirts of two nearby spiral galaxies. For the first time, they have obtained a panoramic overview of an example of galactic cannibalism similar to that involving the Sagittarius dwarf galaxy in the vicinity of the Milky Way.
The detection of these immense stellar fossils confirms the predictions of the cold dark matter model of cosmology, which proposes that present-day grand design spiral galaxies were formed from the merging of less massive stellar systems.
The first of these debris structures surrounds the galaxy NGC 5907, located 40 million light-years from Earth and formed from the destruction of one of its dwarf satellite galaxies at least four thousand million years ago. According to the research team, the dwarf galaxy has lost the greater part of its mass in the form of stars, star clusters and dark matter, all of which has become strewn out along its orbit, giving rise to a complicated assembly of criss-crossing galactic fossils whose radius exceeds 150 000 light-years.

Source: Instituto de Astrofisica de Canarias

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