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Astr110 Photography Projects, Fall 2005

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Dumbbell Nebula, Cassie Zwart and Anneke Branderhorst

Dumbbell Nebula

The Dumbbell Nebula was discovered in 1764 by Charles Messier. This was the first planetary nebula ever discovered, although it wasn't named a planetary nebula until 1784 by William Herschel. Contrary to its name, planetary nebulae have nothing to do with planets. Their name is inherited from their appearance in smaller telescopes as looking like planets.

The Dumbbell Nebula is within the Milky Way galaxy, and is estimated to be at a distance of 1200 light years away from our Solar System. The Dumbbell Nebula is located in the constellation Vulpecula. The angular size is about six  by eight arc minutes, but its halo can extend out to 15 arc minutes. It will continue to grow larger as the gas continues to expand into space. The luminosity class is an O7 meaning the nebula has a high temperature and high luminosity. Our Sun is about 100 times fainter than the Dumbbell Nebula. Although it is not the brightest planetary nebula, it is easy to see through a small telescope in our sky (its apparent magnitude is approximately 8). The central star, a white dwarf, as seen in the photo above, is what gives its large luminosity.

Planetary nebulae are ball-like clouds of dust and gases that surround certain stars. They form when a star begins to collapse and throw off its outer layers of its atmosphere. After a planetary nebula fades from view, the remaining core is a white dwarf star, a star that consists mostly of oxygen and carbon, and is extremely hot because of nuclear burning. Eventually, after the white dwarf has emitted all of its thermal energy it will become a black dwarf. The Dumbbell Nebula's white dwarf is in the central region and can be seen in the photo above.

The colors seen from the nebula are produced by gases. Red is hydrogen, as the blue and green are mostly oxygen produced. The nebula is actually getting larger as the gases expand into space. Its expanding rate is 17 miles per second. Currently its angular size is about 2.09 light years. These gases are heated by the ultraviolet rays emitted from the central star. It is calculated that the highest temperature within the Dumbbell Nebula from the central star at about 85,000 K. Because of this high temperature, it emits a bluish light as seen in our above photo. The reddish color comes from hydrogen emission.

References:

The Cosmic Perspective: Third Edition, Bennett, 2004.
Kopernik
Space.com
Nasa
http://www.seds.org/messier/m/m027.html

Right Ascension (J2000) 19h59m36.0s
Declination (J2000) +22:43:00
Filters used blue(B), green(V), red(R)
Exposure time per filter 60 seconds in BVR
Date observed

November 5, 2005 (V),(R)
November 19, 2005 (B)