23 September 2010

Belly Up to the Bar

What would inhabitants of the Andromeda galaxy see when they peer at the Milky Way through their extraterrestrial telescopes?  In illustrations and planetarium shows, you often see our home galaxy depicted much like the picture to the left: a bright and round central bulge, surrounded by feathery spiraling arms. 

But that's not the case.  More and more evidence is gathering that the Milky Way is actually a "barred spiral"in other words, a galaxy with a straight bar of stars running through its center.  In fact, the Milky Way probably looks a lot like NGC 1365, a grand barred spiral some 60 million light-years distant that just had its picture taken (to the right) with a new infrared camera mounted on the European Southern Observatory's Very Large Telescope in Chile. 

Does that mean the Milky Way and NGC 1365 are special?  Not at all.  Astronomers estimate that around two-thirds of all spiral galaxies display a barred structure.  By looking at NGC 1365, we get a peek at the architecture of our own cosmic home.

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