Astr111 Photography Projects, Fall 2005

M76 Little Dumbbell Nebula, Stephanie Watkins

A nebula is a cloud of gas in space that forms when a star cannot burn hydrogen atoms at its core anymore. The center star then starts to collapse and heat up. High temperature causes the outer part of the star to blow away as a stellar wind. When all of this is done, the core is uncovered and heats up the gasses and makes them glow. This happened in the case of the Little Dumbbell nebula as well, which explains the rings around its core. Little Dumbbell, located in the constellation Perseus, was discovered by Pierre Méchain on September 5, 1780. It was first thought that this nebula was actually two nebulae because of the rings around the body of the object. However, upon later observations, it was discovered to be only one. This particular nebula isn’t very bright. Its magnitude is 10.1 (larger numbers mean dimmer objects). The little dumbbell’s distance from the Earth is difficult to pinpoint. There are estimates from 1,700 light years to 15,000 light years. There are many names for this nebula, the most common being the Little Dumbbell. It is also known as cork nebula, butterfly nebula, and barbell nebula.

The little dumbbell nebula has rings billowing out from the core. This is because, as stated above, the star had no hydrogen to burn, and it emitted stellar winds, causing the rings to appear. The heat emitted caused the rings to glow. The color of this particular nebula is important because it tells us the nebula's compostition rather than how hot it is. The glowing red color is from excited hydrogen atoms coming down to a lower state of excitement. The green color is actually from oxygen, which, while abundant on Earth, is actually rare in the rest of the universe. This tells us that early on in the star's life, it was converting hydrogen into oxygen and then ejecting it into space, where it glows green. My estimated angular size of Little Dumbbell is 8.0 arc minutes, and my estimated linear size is 7.91 light years (assuming that the nebula is some 3,400 light years away from Earth).

References:
www.seds.org/messier/m/m076.html

http://www.noao.edu/jacoby/pn_gallery.html

www.astrosociety.org/education/publications/tnl/14/14.html

http://curious.astro.cornell.edu/question.php?number=296

TheSky 5 software

Professor Larry Molnar, professot of Physics and Astronomy, Calvin College