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Physics & Astronomy Department

Astr110 Photography Projects, Fall 2006

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Bubble Nebula (NGC7635) -Rachel deLange

Helix Nebula

A Nebula is an interstellar cloud of dust, gas and plasma. Nearby this particular nebula is an open cluster. An open cluster is formed from a huge molecular cloud that has up to a couple thousand stars, all gravitationally bound to one another. Unlike global clusters, open clusters are very loosely bound to each other and they are found in spiral and irregular galaxies only. Active star formation is necessary for open clusters to form. The formation of an open cluster is triggered when part of a giant molecular cloud (made up of cold dense gas) collapses. From there, the cloud continues to break into smaller and smaller clusters, forming thousands of new stars. Open clusters are often unstable because they have small masses. This sometimes allows the escape velocity to be lower than the average velocity of its stars. If the mass drops enough, the cluster will quickly disperse. The constellation of Cassiopeia contains Messier 52 which is part of a widefield view called NGC7635-The Bubble Nebula. The Bubble Nebula is about 35 arcminutes southwest of the open cluster M52, is 10 light-years wide, and is about 11,000 light years away from the Earth. The open cluster M52 and Bubble Nebula were found in the rich Milky Way field by Charles Messier on September 7, 1774.

This image of the bubble was captured on October 18, 2006 in the very early morning. The star cluster is viewable in pinks, blues and purples and spread out over the sky. The outline of the bubble is centered and pinkish in color. The Bubble Nebula, seen above gets its shape when wind comes off its brightest star, and pushes the gas in the area into a giant bubble. The high-energy ultra-violet light from the star then ionizes the gas, making it glow. The blue in the bubble is oxygen. The angular size of the Bubble Nebula was about 7 arc seconds. Using the small angle formula, I found the linear size to be about 22.4 light years.

 

References:

Kronberg, Christine and Frommert, Hartmut. "Messier 52." Students for the Exploration and Development of Space.
<http://www.seds.org/Messier/m/m052.html>

Wikipedia. "Nebula."
<http://en.wikipedia.org/wiki/Nebula>

Koprolin, Walter. "M52 and NGC 7635 - Bubble Nebula Region." Gallery of Astrophotography and CDD images. <http://www.nightsky.at/Photo/Neb/NGC7635_WN.html>

Lodriguss, Jerry. "Catching the Light, Open Cluster of M52.." Showcase of Digital Astrophotography. <http://www.astropix.com/HTML/SHOW_DIG/033.HTML>

 

Right Ascension (J2000) 23:20:42
Declination (J2000) +61:12:0
Filters used blue(B), green(V), red(R), and clear(C)
Exposure time per filter 5x2 seconds in B, 5x5 seconds in C, 5x1 second in VR
Date observed

October 18, 2006