Wednesday, April 18, 2007

HCG-51

HCG-51 is a small grouping of 7 galaxies, 5 of which are fainter than magnitude 14, and the other two just bright enough for William Herschel to come across back in the 1780's and get an NGC designation. Located around 4 degrees north east from Delta Leonis, the grouping nicely fits into the Faulkes's field of view.


Using the Aladin Sky Atlas I was able to identify more formal designations of the members, taking the names from the Uppsala General Catalogue (UGC), the Morphological Catalogue of Galaxies (MCG), and the (now superseded) LEDA catalogues. What I could not find was galaxy classifications for these objects.

The best current images of HCG-51 I found on the internet were taken as part of the Palomar Observatory Sky Survey (POSSII). These images just don't quite get to the resolution of this Faulkes image though, so maybe some of the structures are being seen here for the first time .... which is a rather nice though!

Members a, e, f, and g certainly seem to be various forms of elliptical galaxies, and b is certainly a barred spiral, but c and d are a bit more interesting. D, to me, seems like a face on spiral - only just visible in this image with its clockwise arms, and c could almost be construed as a mini Sombrero, viewed from slightly underneath, with its distinct dust lane across its central bulge.

There are a few other very faint galaxies in this image to the centre bottom. As with other Faulkes images, I have been unable to locate any database that can tell me what these objects are.

But, on a final intriguing note of interest, is the "star" on the face of HCG-51b. This is not on the Palomar plates , and is not a hot pixel as it tracks with the
R exposures across the frame, though it is not very visible on the V and B frames. Could it be a super nova or something similar? I don't know, but one can wish :) Maybe a follow-up observation is needed ...

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