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ASTRO: Arp 104 "Rawhide Galaxies?"
Keenan's System NGC 5216 (south, bottom) and NGC 5218 north. Classed by
Arp under "Elliptical and elliptical-like Galaxies: Connected to Spirals" One note says: "Distorted spiral with an S0 companion, well separated but with a connecting arm. North (spiral) is NGC 5218, which has no bright nucleus. To me though these are the "Rawhide Galaxies." For some reason every time I look at the image the Rawhide theme song jumps into my head. And I rarely watched the show. The lines: "Don't try to understand 'em, Just rope and throw and grab 'em, Soon we'll be living high and wide." seem to fit this pair. There's confusion about which galaxy is which. Here's the NGC Project on this issue: "NGC 5216 and NGC 5218. The MCG identifications are reversed from those by all other observers. There is no apparent reason for this in the NGC itself, and I doubt that Vorontsov or his colleagues consulted JH's 1833 catalogue where there is an identification error. For the record, Sir John makes his h 1635 a "nova" while he incorrectly labels h 1636 as H II 841. Sir William's original observation was of two objects which became H II 841 and H II 842. Sir John got the identifications sorted out for the GC, and the NGC has them exactly correct, too." So, the MCG is the only catalogue which reverses the identifications. All the other modern catalogues are correct in placing N5216 south-preceding N5218. - Dr. Harold G. Corwin, Jr." NED puts pair at 153 million light-years but puts NGC 5216 at only 140 million light years and classed as E0 pec, and 5218 at 139 million light years classed as SBb pec and as a LINER galaxy as well. The interaction may have triggered the activity needed to create a LINER status for the galaxy. The lower galaxy NGC 5216 reminds me of Arp 165 ( http://www.spacebanter.com/attachmen...tid=2474&stc=1 ) which was an elliptical galaxy with a faint blue arm but no sign of any galaxy it had interacted with. NGC 5216 is very similar but this time we know the culprit. It didn't fare very well in this near collision either. The galaxy east of NGC 5216 is SDSS J133257.25+624038.6 an IR galaxy 1.3 billion light-years The galaxy NE of 5216 AT 3.7 billion light-years IS MAG 20.8 another, east of NGC 5218 at 3.6 billion light-years is blue with the same magnitude but appears fainter. Above that galaxy listed at 3.6 billion light-years is a very blue star. It is listed as a white dwarf. Usually one this blue has a planetary nebula around it. This one obviously doesn't. In any case it is one super hot but tiny star! MaxBCG J202.88728+62.64181 BCG at 2.63 billion light-years is the anchor galaxy of the galaxy cluster of the same name (without BCG at the end). it consists of some 28 members many of which show in my image as orange dots around this galaxy to the lower right of the NGC 5216. The color contrast with the quasar below it is very strong. There is a pair of nearly overlapping galaxies in upper right corner. They are SDSS J133039.33+625507.1 at 2.7 billion light-years and SDSS J133038.56+625508.8 with no red shift data so it is marked with a "?". Thus I don't know if they are interacting or not. The Q? above NGC 5218 denotes a possible QSO candidate per NED. Though its status is rather indeterminate. It is classed as SDSS J133038.56+625508.8, a quasar candidate; a galaxy in the Sloan Digital Sky Survey and Galex; and an ultraviolet orbiting observatory classes it as GALEX 2685493392111045227 an ultra violet excess source which isn't surprising considering its blue color. The US Naval Observatory has it classed as VisS which just means it is an unknown object visible in ordinary light. I found no distant estimate for it. In the upper left corner is a somewhat blue double galaxy. At least it has two condensations. Oddly I can find no cataloged object at its location. In fact there's nothing of its brightness cataloged within several minutes of arc of this location. Yet the area is covered by the SDSS. I checked the POSS II plates and it is a real object. How the pros let this one get away I don't know. Arp's image is at: http://nedwww.ipac.caltech.edu/level...ig_arp104.jpeg It is located in Ursa Major above the Big Dipper's handle right at the boundary with Draco not far from Thuban. 14" LX200R @ f/10, L=9x10' RGB=5x10', STL-11000XM, Paramount ME You'll notice I put in more than twice my normal time on this one. The extra time really helps with faint ones like this pair. 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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