Sunday, 22 October 2017

IC10: Starburst in our Local Group

As I already explained in this post, our Local Group of galaxies has a lot more to offer than the Andromeda and Triangulum galaxies. Actually, its smaller and more obscure members often seem to hide the biggest surprises. IC10 in Cassiopeia is another dwarf galaxy that only recently has been confirmed as a Local Group member. It's a bit larger than Barnard's Galaxy (13,000 light-years across compared to 7,000) and resembles the Large Magellanic Cloud a lot. Unfortunately it lies 2 million light-years away and appearing close to our galaxy's plane a lot of its light is absorbed by interstellar dust. All of this means that it's a challenging object for visual astronomers, as you can also see on my sketch. This is really a pity because IC10 seems to be a mild starburst galaxy, perhaps generating the most active star formation in our Local Group. If it continues at this rate, it will have spent its entire gas supply in the next one to two billion years! 

This radiant activity shows very well on long-exposure photos, where one can identify dozens of star- forming regions. Through the eyepiece of an amateur telescope, on the other hand, this little galaxy only appears as a very faint blob and even with my 18" binoscope I could only imagine a hint of these massive star-forming clouds.

Another interesting feature of this galaxy is that it's enveloped by a huge bubble of hydrogen gas which appears to be rotating in the opposite direction as the galaxy itself!

It's approaching us at 350km/s, which means that it's bound to collide with our Milky Way in 1.7 billion years...

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