Sunday 23 November, 2014

How bigger galaxies eat smaller ones

Published On: Thu, Jul 3rd, 2014 | Astrophysics | By BioNews

Astronomers studying the feeding habits of a cosmic cannibal have found how bigger galaxies absorb smaller ones.

A team of researchers from Australian Astronomical Observatory (AAO) has been studying the Umbrella Galaxy, formally called NGC 4651, and they have found that it is eating a smaller galaxy. It gets its nickname from the wispy “parasol” that surrounds it.

Its distinctive arc is made up of the crumbs from a single dinner, rather than a series of meals, the astronomers determined.

When scientists discovered this umbrella in the 1950s, they interpreted it as a dwarf galaxy companion to the bigger galaxy.

“Through new techniques we have been able to measure the movements of stars in the very distant, very faint, stellar stream in the Umbrella,” Caroline Foster from Australian Astronomical Observatory (AAO) was quoted as saying.

“This allows us to reconstruct the history of the system, which we could not before,” Caroline added.

Umbrella Galaxy is a twin of the Milky Way and astronomers have shown that our own Milky Way has fattened up by acquiring stars from other, smaller galaxies.

They found streams of star crumbs emanating from the nearby Sagittarius dwarf galaxy, which is being engulfed by the Milky Way.

The astronomers used observations from the Subaru and Keck telescopes in Hawaii, and they tracked the movement of the stars in the stream by looking at globular clusters, planetary nebulae and patches of hydrogen gas in the galaxy, Space.com reported.

The study will appear in a forthcoming issue of the journal Monthly Notices of the Royal Astronomical Society.

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