Astr112 Photography Projects, Fall 2007

Blue Snowball Nebula (NGC 7662), Joel Kooistra

The Blue Snowball Nebula is a planetary nebula in the Andromeda Constellation. It is one of the easiest planetary nebulas to observe with a small telescope. It appears blue-green with a faint white dwarf star in the center. A planetary nebula is the result of the star burning off all of its hydrogen fuel. The star goes through several stages, such as becoming a red giant and burning helium, until it is no longer hot enough to do fusion reactions. Once it is no longer burning fuel it does not have the pressure to withstand the gravity. The core of the star is condensed into what is known as a white dwarf, which is no longer able to hold onto all the material of the star. Thus, it all drifts away from the star in a cloud of gas. The gas in this nebula has drifted away in an almost uniform way to give the impression of a ball. It is thought this is what the Sun will look like once it has burned off all of its fuel. The Blue Snowball Nebula is estimated to be 2200 light years away from our Solar System.

This image shows the uniform distribution of gas around the central white dwarf. The white dwarf is faintly visible in the middle of the nebula. There is a distinct ring around the white dwarf which is a wall of expelled gas. The black and white image allows for more detail to be shown, but does not show the brilliant blue color of the nebula. From this image I calculated a linear size of 0.5 light years across for the nebula, measuring from the faintest edges.

References:
Balick, B. "The Blue Snowball Planetary Nebula." Astronomy Picture of The Day. <http://antwrp.gsfc.nasa.gov/apod/ap961121.html>

Dyer, Allen. "The RASC Finest NGC Objects List." Students for the Exploration and Development of Space <http://www.seds.org/messier/xtra/similar/rasc-ngc.html>.

Darling, David. "Blue Snowball Nebula (NGC 7662)."
<http://www.daviddarling.info/encyclopedia/B/Blue_Snowball_Nebula.html>