NGC 0007 – nearby quasars and alignments

This system hasn’t been discussed as a discordant redshift system before, at least to my knowledge.

Objects 3 (see Figure 1) and 4 form a pair alignment across NGC 0007. Their separations from NGC 0007 are similar, but their redshifts are not similar. The alignment with these two is not exactly across the nucleus of NGC 0007. Another option for pair alignment would be objects 3 and 6. Their separations from NGC 0007 is not similar, but redshifts are closer to each other than in 3 – 4 pair, and both objects are QSO’s. Alignment across the nucleus of NGC 0007 in this case is almost exact.

There’s another, very rough pair alignment across NGC 0007. It’s with objects 7 and 11. Although the alignment is very rough, the interesting thing here is that redshifts of the two are very close to each other (0.1390 and 0.1395). However, it has to be noted that also object 8 has similar redshift (0.1389), so there is a possibility of a background group of galaxies.

Objects 3 and 5 have very similar redshift (2.062 and 2.041). The nominal redshift difference is little large for physical pair, the nominal velocity difference is 2070 km/s. However, if we consider the given error bars for the redshift measurements, the velocity difference might be only 1080 km/s. But even that is still rather high for a physical pair, but perhaps acceptable. It is also interesting to note that the field has three quasars, all of which are positioned near NGC 0007. The field has been covered by 2dF quasar search, so one would expect roughly homogenous distribution of quasars. In that light, the presence of the three quasars near NGC 0007 would suggest either a deviation from homogeneity of 2dF quasar search for some reason, or some kind of association between NGC 0007 and the three quasars. But, chance projection can never be ruled out in these cases either.

Object 10 seems to be a real companion candidate to NGC 0007 because it has similar redshift (the redshift velocity difference between the two is less than 150 km/s).

ngc0007
Figure 1. The objects with measured redshifts near of NGC 0007. 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 0007 SBc? 0.004987 (1495 km/s) 13.47 0
2 6dF J0008227-295413 PofG 0.005325 (1596 km/s) 15.5 (R) 0.782
3 [VCV2001] J000827.5-295422 QSO 2.062000 19.53 1.513
4 2dFGRS S359Z113 galaxy 0.124839 19.18 1.947
5 [VCV2001] J000826.5-295749 QSO BAL 2.041000 20.74 3.177
6 [VCV2001] J000802.7-295631 QSO BAL 1.591000 20.23 4.269
7 2dFGRS S360Z141 galaxy 0.139000 18.83 6.162
8 2dFGRS S359Z094 galaxy 0.138856 18.53 6.764
9 2dFGRS S359Z122 galaxy 0.061288 18.48 7.911
10 2dFGRS S359Z100 galaxy 0.005437 (1630 km/s) 17.12 8.304
11 2dFGRS S278Z243 galaxy 0.139495 18.39 8.712

NED object list with available redshifts within 10 arcmin.

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