Thursday, 1 March 2018

NGC2022: Unnamed and underestimated

It amazes me time and time again that some of the most exotic and least-known objects still carry a popular nickname. Take IC418, for example, the Spirograph Nebula. Not that our Spirograph doesn't deserve a nick, much on the contrary since it's such a beautiful object. But then what about NGC2022, the brightest planetary nebula in Orion? It's a very popular nebula but still no-one seems to have found a nice name for it. 

I guess that the reason for this is that it's so small, although far from as small as IC418. In small to medium-sized telescopes NGC2022 appears almost stellar and you need a bit of aperture and especially very high magnifications in order to bring out some detail. At 507x, however, the bright ring of its inner shell stood out brightly against the thin haze of its outer envelope. Inside of the ring I saw strings of matter connecting it to the 16th magnitude central star, surrounded by abundant detail. I even thought to have caught a glimpse of a tiny star that looks as if it lies on the western part of the ring.

Distance estimates are always difficult with nebular objects and our best guess is that this nebula lies about 8,000 light-years away, so more than double the distance to the Spirograph. Yet, NGC2022 dwarfs it in size, indicating that it is far more evolved with its bright inner shell having almost caught up with its outer, which stretches over a light-year across. The extremely hot (surface temperature 108,000°C!) white dwarf whence the nebula originated has probably reached the point of maximum heating, after which it will cool down and extinguish slowly. 

To me, the nebula looked very much like a grape so I'd like to baptise it officially "Grape Nebula". Perhaps you have a better proposal for a nickname? I'm all ears... :-)

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