NGC 5015 – exact pair alignments

NGC 5015 (object 1 in Figure 1) has not been studied much, and I’m not aware of it being mentioned as DRS before. So, let us see what we have there.

Object 2 has similar redshift to NGC 5015, so it’s not a discordant redshift object. It looks very interesting object, though. It seems to have a visible straight bridge to the bar/nucleus of NGC 5015. However, details are difficult to determine with available images.

Objects 3 and 4 are quite well aligned with the nucleus of NGC 5015. Both objects have discordant redshift to NGC 5015, but their redshift is not similar. Redshift of object 4 is almost twice the redshift of object 3 (z4 / z3 = 1.82). Worth mentioning here is that objects 3 and 4 are the nearest two higher redshift objects to NGC 5015, and they happen to be aligned across the nucleus of NGC 5015. Also, the alignment axis is quite close to the minor axis of NGC 5015.

Objects 9 and 15 are almost exactly aligned across the center of the nucleus of NGC 5015. Their redshift are very different to each other. Alignment axis is very accurately on the minor axis of NGC 5015. This pair is aligned in similar direction from NGC 5015 than the pair of objects 3 and 4, but this pair is further from NGC 5015. Higher redshift object of this pair has lower redshift than the higher redshift object of the 3/4 pair. Lower redshift object of this pair has lower redshift than the lower redshift object of the 3/4 pair. However, the higher redshift object of this pair has higher redshift than the lower redshift object of the 3/4 pair, so the configuration doesn’t provide an exact fit to decreasing redshift hypothesis even if some aspects of it fit.

Object 9 seems to be quite compact and small object considering how small it appears and how low redshift it has. Compare it to NGC 5015; according to redshift object 9 should be roughly twice as far as NGC 5015, so it should very roughly be two times smaller than NGC 5015. Major diameter of object 9 is 0.17 arcmin while the major diameter of NGC 5015 is 1.8 arcmin, so NGC 5015 is ten times larger than object 9. Whatever object 9 is, it is not a regular galaxy.

Objects 10/16 and 14 are quite well aligned with the nucleus of NGC 5015. They all have different redshifts. Object 16 is the only known quasar in the field. By curious coincidence, like in the 3/4 pair, the redshift of object 14 is almost twice the redshift of object 10 so that z14 / z10 = 1.81, when it was 1.82 for the 3/4 pair.

Objects 8 and 12 are almost exactly aligned across the center of the nucleus of NGC 5015. Their redshifts are somewhat similar.

Objects 4 and 5 have similar redshift, so they are a possible galaxy pair. Same goes for objects 7 and 8, but there’s also one additional object at the same redshift little outside the pictured field of Figure 1. Few objects in the field have redshift of about z = 0.13. They are objects 6, 12, 14, and 15. Few objects little outside the pictured field have the same redshift, so we are looking at the possible galaxy group at z = 0.13.

So. out of 17 objects we got 4 pair alignments, of which two were almost exact.

ngc5015
Figure 1. The objects with measured redshifts near of NGC 5015. Size of the image is 15 x 15 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU Red), and it has been adjusted for brightness and contrast to bring out the faint objects in the field.

Objects and their data

NBR NAME TYPE REDSHIFT (cz) MAG SEPARATION
1 NGC 5015 SBa 0.010504 (3149 km/s) 13.24 0
2 2dFGRS N134Z004 galaxy 0.010200 (3058 km/s) 18.12 0.568
3 2dFGRS N134Z011 galaxy 0.086800 17.85 2.986
4 2dFGRS N134Z005 galaxy 0.158200 18.55 3.561
5 2dFGRS N135Z283 galaxy 0.156800 19.40 5.234
6 2dFGRS N134Z012 galaxy 0.131900 18.74 5.439
7 2dFGRS N134Z014 galaxy 0.176600 19.04 6.396
8 2dFGRS N135Z278 galaxy 0.177735 19.53 6.564
9 2dFGRS N134Z001 galaxy 0.017500 (5246 km/s) 18.77 7.012
10 2dFGRS N134Z340 galaxy 0.074800 18.90 7.306
11 2dFGRS N135Z281 star 0.000400 (120 km/s) 19.20 7.326
12 2dFGRS N134Z034 galaxy 0.133700 18.69 7.468
13 2dFGRS N134Z033 galaxy 0.063400 19.30 7.554
14 2dFGRS N134Z028 galaxy 0.135200 18.00 8.027
15 2dFGRS N134Z016 galaxy 0.130900 19.51 8.257
16 PKS B1310-041 QSO FSRQ 0.824900 18.7 (B) 8.385
17 2dFGRS N135Z280 galaxy 0.049600 18.61 8.805

NED objects within 10 arcmin from NGC 5015.

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