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ASTRO: Arp 203
Arp 203/NGC 3712 is located about 90 million light-years away in the
constellation of Ursa Major just across the border from Leo. In fact the south edge of my image is only a few seconds of arc into Ursa Major. Arp put it in his category for galaxies with material ejected from nucleus. So what material is he referring to? I have no idea. His comment says "Faint plumes coming off both ends of bar." Is this the material? NED classes it as SB? as does the NGC project. The "bar" is rather broken up. It consists of three bright parts. A lower elongated piece and two round pieces north of it oriented at an angle to the lower piece. Further north are two faint condensations. The northern one brighter and designated by the SDSS as a separate galaxy with no red shift given. Arp 203 does have one obvious companion, or galaxy at about the same distance near the same line of sight. It is SDSS J113119.85+283125.0 at 83 million light years. It's a rather featureless galaxy that NED makes no attempt to categorize. Both are rather small galaxies. Since it is undistorted I doubt it is the cause of the plumes seen coming from Arp 203. Could it be a merger. The multiple bright blobs in the core would seem to make this a possibility. I found no papers discussing anything about its plumes other than pure descriptions. Though I didn't search very deep. Still it seems to be a poorly studied galaxy. NED and the SDSS have some communication errors involving this one or maybe the problem is solely with the SDSS. In any case the SDSS doesn't recognize NGC 3712 in the NED data base nor at their own finder web page. In fact put in the coordinates for NGC 3712 and it says the field is not in the survey! Put in the coordinates for its position for NGC 3712 which it enters as SDSS J113109.36+283359.3 which is the position of the lower of the three blobs that seem to define the bar and then it finds it. Just a few seconds of arc north and it returns the out of field error. It also lists a rather bright 20th magnitude galaxy a bit east of Arp 203 that does exist but is about 24th magnitude not 20th which had me going for a bit. There are other errors but I didn't pursue them, just cussed and went on. In the upper left corner you can find ZwCl 1129.4+2858, a galaxy cluster of unknown distance with 68 members in an 11' field. The label marks the center. Most that I see are to the upper left of that position. But redshift distances of galaxies within 5.5 minutes of the center all have very different values ranging from 2.3 to 5 billion light-years. At least the galaxies with redshift values are just a line of sight group rather than a true cluster of gravitationally bound galaxies. If there's a true cluster here redshift values aren't disclosing it. This was taken early in the morning of April 15, 2010 so I am now officially a year behind in my processing Arp's image http://nedwww.ipac.caltech.edu/level...ig_arp203.jpeg 14" LX200R @ f/10, L=6x10' RGB=2x10'x3, STL=11000XM, Paramount ME Rick -- Correct domain name is arvig and it is net not com. Prefix is correct. Third character is a zero rather than a capital "Oh". |
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