Astr111 Photography Projects, Fall 2009

NGC 6960 (Western Veil Nebula), Zig Ingraffia

The Veil Nebula, part of the Cygnus loop, is composed of the faint remnants of a Milky Way star that exploded some 5-10,000 years ago. The entire shell of the nebula spans a full 3 degrees across the sky, though only a small segment of the western portion of the nebula is pictured above. Supernova remnant nebulae such as this one occur when a high-mass star ceases nuclear fusion and collapses in upon itself. As the gas falls inward, it becomes so heated that it explodes outward from the core, sending a shell shaped shockwave of super-heated gas expanding outward, which then produces visible light as it smashes against the interstellar medium and radiates heat over time.

The blooms (discolored vertical stripes) of the bright stars near the center of this image (in particular that of the brightest star right at the center of the picture, 52 Cygni) could not be cleanly removed, but the faint remnants of the supernova are visible above and to the left of these objects. 52 Cygni has a magnitude of 4.22, making it the only object in this image visible with the naked eye under even good conditions. As you can see, the relative faintness of the nebula in comparison to this star explains why it is not visible even though its total size in the sky corresponds to nearly 6 full moons. The Veil Nebula is around 1400 light years from earth, and the portion of it seen within this image has an angular size of approximately 16 arcminutes. This means that this section of the nebula's linear diameter (from the top of the image to the bottom) is around 6.5 light years across (the entire Veil Nebula being around 100 light years accross). Also note the red and green coloration of the nebula. We saw in class that red is indicative of hydrogen gas, while the green indicates the presense of ionized oxygen within the nebula.

References:
Robert Nemiroff (MTU) & Jerry Bonnell (UMCP). "NGC 6960: The Witch's Broom Nebula."<http://apod.nasa.gov/apod/ap080819.html>.

Christensen, Lars L. and Villard, Ray. "Uncovering the Veil Nebula." <http://www.spacetelescope.org/news/html/heic0712.html>

Kuhn, Karl F.and Koupelis, Theo. "In Quest of the Universe." 3rd Edition.