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Wildrik Botjes Planetarium
Physics & Astronomy Department

Astr110 Photography Projects, Fall 2006

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Little Dumbbell (M76), Ben Sneller

Little Dumbbell

Planetary Nebula M76 was first discovered in 1780 by Pierre Mechain who then reported it to Charles Messier. Charles then observed it and decided its position and added it to his catalog, this is why there is an "M" in front of it. The nebula is often referred to as "little dumbbell" after M27, or the "Dumbbell Nebula", because it looks very much like it. And like its brother the "Dumbbell Nebula", the "Little Dumbbell" is considered a planetary nebula- "a gaseous shroud cast off by a dying sun-like star" (Astronomy Picture of the Day). The estimated distance to M76 is three to five thousand light years away, which "makes the nebula around a light year in diameter" (Astronomy Picture of the Day). I found that the linear size of M76 is 7.6x10^12 Kilometers and an angular size is approximately 42.85".

As you can notice the "wings" of the nebula are quite a bit fainter than the middle, this is because along the axis perpendicular to the plane gas is expanding significantly more rapid than the center to form the "wings". The faint halo covering the object is material "probably ejected in the form of stellar winds from the central star when it was still in the Red Giant phase of evolution" (Frommert and Kronberg). The central star is, as you can notice, a bluish tint which implies its high temperature: "Today the central star is of mag 16.6 and a high temperature of some 60,000 K, which will probably cool down as a white dwarf over the coming tens of billions of years"(Frommert and Kronberg). The "wings" are then a greenish tint which imply they are a relatively low temperature considering the spectrum.

References:
Frommert, Halmut, and Christine Kronberg. "Little Dumbbell Nebula." Messier 76. 11 Aug. 2005. 13 Nov. 2006

"Astronomy Picture of the Day." Nasa. NASA. 13 Nov. 2006

Right Ascension (J2000) 01:42:18
Declination (J2000) 51:34:9
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x6 sec in C, 1x1.8 sec RV, 1x2.4 sec B
Date observed

October 12, 2006 (BVRC)