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Eskimo Nebula (NGC 2392)
Evan Cook

NGC2392

When William Herschel discovered the Eskimo Nebula in 1787, he recorded it as, "A star 9th magnitude with a pretty bright middle, nebulosity equally dispersed all around. A very remarkable phenomenon." It is indeed a remarkable object, and even 230 years later, scientists still do not fully understand its structure. The Eskimo Nebula is a bipolar planetary nebula. Planetary nebulas are the result of the death of a star roughly the mass of our Sun. During the later stages of its life, the star sheds its outer layers in the form of intense solar winds, often forming complex ringlike structures of gas. The core of the star collapses down into a white dwarf, an incredibly hot, compact sphere of carbon and other elements about the mass of the Sun, but about the size of Earth. Light from the white dwarf excites and ionizes the shed gases, which glow at wavelengths specific to their composition, lending clues as to the makeup of the nebula. The Eskimo Nebula is also bipolar, which means that it has two main lobes. Often as a planetary nebula forms, there is a denser ring of dust and gas around the star that forces the shed gasses either above or below the ring, giving rise to two lobes of gas. However, we see the Eskimo Nebula end on, so the two lobes appear to be one.

In this image, we can see the very bright central region containing the white dwarf. Although it appears fairly large in the image, in reality it is only about the size of Earth, and would actually appear as a point on this scale. However, it has saturated the pixels around it, causing it to appear much larger than it actually is. It is worth noting how such a small object can emit such an enormous amount of high energy radiation. The reason is that the white dwarf is incredibly hot, with surface temperatures on the order of 100,000 Kelvin. Around the core, we can see a bright green ring of oxygen gas. This is the two lobes that we see as one. Further out is a larger sphere of gas that, while it still contains oxygen, also contains a large amount of reddish hydrogen gas. While it is hard to see in this image, the hydrogen gas is organized in what appears to be finger-like filaments extending radially outward from the center of the nebula. It is possible that these are similar to the extended filaments seen in the Ant Nebula, but seen end on instead of from the side. In the end, the Eskimo Nebula is a wonderful example of the homology, and yet the beautiful diversity of planetary nebulae.

References:

Nemiroff, Robert, and Jerry Bonnell. "The Eskimo Nebula from Hubble and Chandra." NASA. <http://apod.nasa.gov/apod/ap130730.html>

Erdmann, E. Robert. "NGC 2392." The NGC/IC Project. <http://www.ngcicproject.org/ngcicdb.asp>

O'dell, C. R.; Balick, B.; Hajian, A. R.; Henney, W. J.; et al. (2003). "Knots in Planetary Nebulae". Winds, Bubbles, and Explosions: a conference to honor John Dyson, Pátzcuaro, Michoacán, México, September 9–13, 2002 (Eds. S. J. Arthur & W. J. Henney) Revista Mexicana de Astronomía y Astrofísica (Serie de Conferencias) (http://www.astroscu.unam.mx/~rmaa/) 15: 29–33. Bibcode:2003RMxAC..15...29O.

Wikipedia, "Planetary Nebula".

Wikipedia "Bipolar Nebula".

Wikipedia, "Eskimo Nebula".

Right Ascension (J2000) 07:29:11
Declination (J2000) +20:54:42
Filters used B (Blue), R (Red), V (Green)
Exposure x number of images for each filter B (60s x 10), V and R (22s x 10);
Image dimension 298x267 pixels; 1.63x1.46 arcminutes
Date/time observed April 22, 2016, 01:45 UT
Distance 900 pc
Scale 0.26 pc/arcminute

 

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