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Physics & Astronomy Department

Astr110 Photography Projects, Spring 2009

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M81 (NGC 3031) or Bode's Galaxy, Ashleigh Doornbos

m81

M81 (NGC 3031) is a spiral galaxy, also known as Bode's Galaxy - refering to the man who dicovered it - Johann Elert Bode in 1774. Spiral galaxies, much like our own Milky Way, are spinning disks of dust and gas. A fun fact about spiral galaxies is that there are black hole at it's center. M81 is a very conspicuous spiral galaxy in the northern part of Ursa Major, and can be seen by ametuer astronomers on clear nights. It is about 70,000 light-years across and only 12 million light-years away.

A Fun Fact: The closest object in the sky to M81 is the neighboring galaxy M82, also discovered that same day by Bode. Their centers are separated by a linear distance of only about 150,000 light years. A few tens of million years ago the galaxies M81 and M82 came very close to each other, which resulted in the more massive M81 to dramatically deform it's neighbor by gravatational interaction.

The image of M81 above was made by mosaicing two images together. In my image the arms are very faint, but they become more prominent when under a UV light since the many stars in the arms are hot young stars. The bulge in the middle consists of much older stars but in a high concentration since they are so close together. The Angular size of the image from top to bottom is 20 arcminutes. This corresponds to the Linear size of 72,000 light years. In the black and white photo we see a faint spiral with a bright glow in the middle, which clearly shows that there are other galaxies in the vastly huge universe. Our God is truly amazing!

References:

Bonnel, Jerry and Nemiroff, Robert. "M81: Feeding a Black Hole." <http://antwrp.gsfc.nasa.gov/apod/ap080627.html>

Frommert, Hartmut and Kronberg, Christine. "Messier 81." Students for the Exploration and Development of Space. <http://www.maa.clell.de/Messier/E/m081.html>

Right Ascension (J2000) 09:55:36
Declination (J2000) +69:04:30
Filters used clear (C)
Exposure time per filter 10x60 seconds in C.
Date observed

March 19, 2009