NGC 7632 – with higher redshift double galaxy

NGC 7632 (object 1 in Figure 1) has been reported to have a higher redshift double galaxy (objects 8 and 9) nearby by Arp (1981). Arp (1982) noted further that:

The central galaxy is disturbed on such a large scale that this large interacting pair seems to be the only possibility to account for such a disturbance.

That should of course be impossible due to discordant redshift of the galaxy pair.

I haven’t found any other papers discussing this system. Figure 1 shows all nearby objects that have redshifts available. The system is not particularly interesting in discordant redshift sense. There’s a pair alignment with objects 6 and 10 aligned across NGC 7632. Objects 2, 3, 5, 6, and 7 have similar redshifts, so they form a probable galaxy group, making the pair alignment of objects 6 and 10 less significant because having a background galaxy group near a low redshift galaxy increases possibility for an alignment with some other background object, or in other words, changing the position of object 10 somewhat would still result of an alignment with some object in the group (the position angle for object 10 that would still give good alignments could change dozens of degrees).

Figure 1. The objects with measured redshifts near NGC 7632. 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

1 NGC 7632 SB0 0.005107 12.95 0
2 LEDA 195478 galaxy 0.095920 18.77 2.179
3 LEDA 123659 galaxy 0.095820 17.49 3.018
4 LCRS B231901.0-424300 galaxy 0.047423 18.07 3.665
5 LCRS B231942.3-424324 galaxy 0.096330 18.10 5.088
6 LCRS B231932.1-424038 galaxy 0.095152 17.45 5.466
7 LCRS B231940.7-424032 galaxy 0.094919 18.05 6.500
8 ESO 291-023 S 0.034754 15.76 6.799
9 ESO 291-022 S 0.034897 15.38 7.182
10 APMUKS(BJ) B231849.62-425237.5 galaxy 0.065002 17.76 8.847


Arp, 1981, ApJS, 46, 75, “Spectroscopic measures of galaxies, their companions, and peculiar galaxies in the southern hemisphere”

Arp, 1982, ApJ, 256, 54, “Characteristics of companion galaxies”

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