Stellar Swirls of NGC 5907 caused by Ancient Galactic Collision

Recent astronomical simulations suggest that the enormous swirls of stars that surround NGC 5907 galaxy which is located 50 million light years away from us, in the Draco constellation, were formed when two galaxies of the same size collided about 9 billion
years ago.

This research was by Wang et al in the journal Astronomy and Astrophysics.

The NGC 5907 is a spiral galaxy and is also known as the Knife Edge or the Splinter galaxy. The spiral  galaxy has anomalously low metallicity and has very few giant stars.

The galaxy is apparently composed of dwarf stars and is the part of the NGC 5866 Group which takes its name from the brightest galaxy in the Messier 102 group which is also known as the Spindle galaxy.

NGC 5907 was long considered a prototypical example of a warped spiral until an extended tidal stream was detected. The stream, which surrounds the galaxy, suggests that the gravitational perturbations were induced by the stream progenitor and may have been
the cause of the warp. The galaxy itself is about 150,000 light-years across.

Previously, researchers had thought that the stellar swirls were formed when a smaller galaxy hit a larger one, but the new study shows that this would have been impossible. In order to produce the observed streams, two roughly equally-sized galaxies crashed
into each other 8 or 9 billion years ago. The simulation also showed that the galaxies must have been rich in gas in order to produce the swirls.

The Milky Way is heading for a crash into Andromeda in 4.5 billion years, and the resulting galaxy could have a similar shape. Most large spiral galaxies are thought to have formed in a similar process.

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Posted by Taimoor Tariq on Feb 20 2012. Filed under Sci-Tech. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry