Sunday, February 2, 2014

Supernova in M-82

About two weeks ago, the brightest supernova in over 20 years has erupted in the nearby galaxy M-82, which is 12-million light years away in the constellation Ursa Major. I wanted to see it as soon as it appeared, but rain and clouds have moved in until three nights ago. When clear weather arrived, I loaded the 15-inch telescope into my car and drove to a darker site than my driveway.

Upon turning my telescope to M-82, I was immediately rewarded with success. There in the central region of the galaxy the supernova was glaringly apparent at magnitude 10.5 or so. It clearly occurred in a dusty region of the galaxy, which has dimmed the supernova by about two magnitudes. The supernova is a type 1A, which occurs when a white dwarf star accumulates so much mass from another star that it becomes unstable, collapses, then explodes from runaway nuclear fusion that spreads through the entire star in seconds. Most white dwarfs are mostly made of carbon and oxygen, so when nuclear fusion occurs in them those elements are rapidly transformed into other elements ranging from neon to nickel. The star was totally destroyed in the explosion and since the supernova actually occurred 12 million years ago, the star is in reality long gone. As for the galaxy itself, the dust lanes and bright regions across it's length were plainly visible through my telescope at 227X.

M-82 and its supernova weren't the only objects I observed that night. One object I stopped to look at was the bright open cluster NGC-1664 in Auriga. Large and bright, it is a fine sight in small and big telescopes. This star cluster is large and rich in bright and faint stars, with a curious kite or Ginko leaf shape. This open cluster has an apparent magnitude of 7.6 and an apparent size of 18 arc-minutes across.

Lepus the Hare has a number of moderately bright and faint galaxies, one of which is the nearly edge-on spiral NGC-1888. Small and moderately bright, this object has an oval outline.  Along one side there's a sharper border where one of the main dust lanes are. The nuclear region was fairly bright and prominent, but over all this galaxy was fairly dim, and hindered by the light dome from my city. This 12th magnitude galaxy is about 3 arc-minutes long and bear magnifying fairly well.

In Auriga lies the open cluster NGC-1893, which is surrounded by the faint emission nebula IC-410. I saw little of it mainly because I concentrated on the cluster and did not use my nebula filters to search it out. The star cluster itself is quite large, rich and appears to have a dark, starless void in it. Spanning 11 arc-minutes and shining at a overall magnitude of 7.5, NGC-1893 sports a rich population of both bright and faint stars.
NGC-2192 is a very different star cluster than NGC-1893 and 1664. While they consist of brighter, younger stars, NGC-2192 is composed of much older and fainter stars. Indeed it's impossible to see from a light polluted area because it fades into the surrounding star field. From a reasonably dark site it is easy to locate with a medium or large aperture telescope as a faint, oval collection of faint and very faint stars. NGC-2192 shines at a magnitude of 11 and an apparent size of 6 arc-minutes.
While known for it's nebulae and star clusters, Gemini also has it's share of moderately bright and faint galaxies. NGC-2339 is a SBbc spiral galaxy that shines at a magnitude of 11.6 and an apparent size of 2.7 by 2 arc-minutes. It is moderately faint with a weakly brighter central core and nearly oriented north to south. There is also a faint star in front of one end of the central bar. This is probably the brightest and easiest of Gemini's galaxies for amateurs to see.

NGC-2389 is another face-on spiral galaxy in Gemini with a classification of Sc. Much smaller and fainter than NGC-2339, this galaxy shines at magnitude 12.8 and an apparent size of 1.4 X 2 arc-minutes. Also visible was the nearby oval galaxy NGC-2388. Shining at magnitude 13.9 and a mere arc-minute long, this spiral galaxy is much harder to see, it took jiggling the telescope to confirm its reality.

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