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Astr112 Photography Projects, Fall 2007

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Little Dumbbell Nebula (M76), Paige Alexander

Little Dumbbell

The photograph above is of the LIttle Dumbbell Nebula (Planetary Nebula Messier 76). A planetary nebula occurs towards the end of a star's lifetime and is a result of material thrown off by said star once it has run out of hydrogen fuel to burn. The Little Dumbbell Nebula (also called the Cork Nebula, Butterfly Nebula, and Barbell Nebula) was discovered on September 5, 1780 by Pierre Méchain. There was an original dispute surrounding what the nebula actually is. Méchain believed it to be a nebula without stars, while Messier, who cataloged the nebula, believed it was "composed of small stars with some nebulosity". It was not until 1918 that the nebula was finally correctly categorized as what it truly is, a planetary nebula. The Little Dumbbell Nebula was originally believed to be a double nebula; however, more observations have showed the nebula to only be a single one. As one of the more fainter Messier objects, the distance to the Little Dumbbell Nebula is, unfortunately, poorly known; however, estimates would distance it between 1,700 and 15,000 light years away from the Earth. It is located in the constellation Perseus.

The appearance of M76 resembles that of M27, the Dumbbell Nebula (http://www.calvin.edu/observatory/images/m27/). Its main body can be seen edge-on and it appears to be a bright, elliptical ring. Along the axis of the ring, the gases expand creating the "butterfly wings" of the nebula. The red color is a result of ionized hydrogen gases, while the green is a result of ionized oxygen. In the middle a faint star can be seen. This faint star was the star from which all these gases have been emitted. The star will eventually, once all the gas has been expelled from it, become a white dwarf, after which it will fade into the vast darkness of space. The approximate angular size of the image is 180" x 240" and the approximate linear size is 6ly x 8ly. In calculating the linear size, I estimated the distance to be 7,000ly, as that is the median of 1,700 and 15,000.

References:
Freedman, Roger A and Kaufmann III, William. Universe: Stars and Galaxies. W.H. Freeman and Company, New York, 2008.

Frommert, Hartmut and Kronberg, Christine. "Messier 76" Students for the Exploration and Development of Space. <http://www.seds.org/MESSIER/m/m076.html>.

Right Ascension (J2000) 01h42m18s
Declination (J2000) +50:34:0
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x60 seconds in C, 300 seconds in BVR
Date observed

October 23, 2007 (BVRC)