Bode and Cigar Galaxies

Object: M81 Bode and M82 Cigar Galaxies

Description: M81 is a great example of what’s known as a “grand design” spiral arm galaxy, a galaxy which exhibits distinct, well defined spiral arm structure. The core of M81 is quite prominent as it is very densely packed with stars, lurking within its center is a supermassive black hole estimated to be around 60 to 70 million solar masses. This photograph of the galaxy reveals the core to be diffused with a faint yellow color, a sure sign that older, cooler stars are packed into this region. The spiral arms however show a distinct blue, white, and pink- a sure indication of the presence of young, hot stars. M82 was once thought to be an irregular galaxy but a study in 2005 showed that, when observed in the near infrared, the galaxy shows two symmetric spiral arms. M81/82 are most assuredly locked in a gravitational embrace and have apparently interacted with one another many millions of years ago. As the two danced close together eons ago the gravitational tidal tug from M81 set off a density wave ripple in M82. As this wave propagated through the dust and gas of the galaxy it triggered a burst of star formation. This photograph of M82 seems to show explosions of gas emanating from near the galaxy’s core, whether this is material being blown out from the core or merely light being reflected off gas that is stationary is still a matter of conjecture. While M81/82 are some 11 million light years from Earth they are only about 100,000 light years from each other. If you were on a planet orbiting a star in either galaxy, just imagine what your view might be like as you looked up into a night sky dominated by the presence of your galactic neighbor.