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Hubble's Var 1 in the Andromeda Galaxy, Messier 31


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The star marked in the image is what Hubble called ""Var 1", It is a Cepheid variable and more often called "M31 V0619" these days. It is of great historical importance because its Cepheid nature was recognized by Hubble; its brightness (around V=19) and period (about one month) told him instantly that it must lie far beyond the boundaries of the Milky Way and that M31 must be a galaxy in its own right, comparable in size to our own.


It lies in a glorious part of the galaxy and this image alone contains several examples of almost everything of interest to the amateur: variable stars, red and blue supergiant stars, open clusters, globular clusters, emission nebulae, dark nebulae and planetary nebulae. About the only things missing are double stars.

21 minutes unfiltered with a SX694 attached to a 0.4m Dilworth at Tacande observatory.

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For instance, here is a globular cluster named B020-G089.  It is comparable to, say, M13 in size and luminosity but shines at magnitude 17.55 because of its much greater distance. M13, on the other hand, has a magnitude of 5.78.  Note that it is noticeably bigger and fuzzier than the neighbouring stars, despite the seeing-limited conditions under which this image was taken.




Above the GC is an emission nebula rather similar to M42 in Orion.

Something for everyone!

Edited by Xilman
Add note about emission nebula
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