One of the most spectacular galaxy pairs in our sky, M81 and M82 are an interacting pair a mere eleven million light years from us. M81 is a placid spiral punctuated with numerous HII regions, while M82 seems to be literally exploding. Doubtless M82, with its much lower mass, took the brunt of the punishment for venturing too close to M81. Supernova SN2014J is visible in M82, further evidence of the fierce stellar winds and frequent supernovae driving the
200 kilometer per second superwind outward from the nucleus. This wind is composed of extremely hot hydrogen, which is both glowing brightly at red Ha wavelengths and in the x-ray spectrum, as well as many heavy elements.
These two galaxies are the largest in a small cluster called "
The M81 Group." This cluster of some thirty galaxies is so close to us that it extends across a very large expanse of our sky, from 7 to 13 hours of right ascension and 63 to 71 degrees of north declination.
This image combines data from both the 17" and 20" Planewave instruments. Bob Finnigan used the 20" to acquire the excellent data for the image of M82, and I used the 17" for the remainder of the image.
Image acquired at Sugar Grove Observatory and Prairie Sky Observatory, facilities of Twin City Amateur Astronomers (tcaa.us).
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