NGC 3501 - Superthin Galaxy
NGC 3501 can be classified as one of the so called "Superthin Galaxies". These are spiral galaxies, which are seen directly from the side (Edge On)
and which have a particularly large ratio of diameter to length, namely 8:1 and more. With a brightness of 13.1mag NGC 3501 belongs to the brighter
galaxies of this type. It was discovered in 1882 by Edouard Stephan.
From the apparent size of 4.0'x0.5' and the known distance of 77 +-6 million light years the true size is calculated to 90,000 light years. So the galaxy
is a little smaller than our Milky Way. It is of Hubble type "Sc" and thus counts as a spiral galaxy. Its mass is 15 billion solar masses, with dust
accounting for just 11 million solar masses. The absolute magnitude is given with M=-19.0mag, which corresponds to a luminosity of 3 billion suns.
But because we see the galaxy directly from the side, the value will surely be many times higher. NGC 3501 also seems to be quite young, because
most of the stars have an age of only 2- 8 billion years.
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In my 20" telescope NGC 3501 appears quite bright and is clearly visible even at low magnification. But the elongated shape is best seen at V=200x
and more. Then you can see a long, thin needle of light in the eyepiece - a wonderful sight when you see something like this for the first time. The
center of the galaxy appears elongated as well.
On photos you can see a dust lane, but nothing of it was visible in the eyepiece.
If you look very closely and know what to look for, you can see a very faint galaxy north of NGC 3501. But this one was not so easy even with averted
vision.
