Arp (1980) reported three new discordant redshift cases. One of the reported systems was AM 0058-402. This system has main galaxy (object 1) connected to an apparent companion (object 2) galaxy with a spiral arm-like bridge. Problem is that main galaxy has radial velocity cz = 6773 km/s while the companion has radial velocity 16415 km/s, so the difference in these velocities is too large for them to be physically connected in traditional view. Arp says this about the bridge:
On this latter higher-resolution photograph, it is seen that the connecting filament is in the nature of a spiral arm emerging from the larger galaxy. But the arm is much longer than any of the other arms in the galaxy, emerges orthogonally rather than tangentially from the main body, and terminates directly at the center of the companion.
Notes
Figure 1 shows nearest objects with measured redshifts in AM 0058-402 field.
- The bridged object, object 2, seems to belong to a group of galaxies at about 16500 km/s. Object 19 (which is just outside the pictured field) is brightest and seemingly largest of the galaxies in this group, and might be the main galaxy of the group. Objects in the group (within this field) are 2, 6, 7, 8, 11, 16, and 19.
- There seems to be another group at redshift z = 0.177. This group seems to be overlapping with the 16500 km/s group described above. Objects in this group are 9, 10, 13, 14, and 17.
- Objects 12 and 15 are roughly aligned across object 1. Object 3 also falls to their alignment line.
Figure 2. The objects with measured redshifts near AM 0058-402. Size of the image is about 15 x 15 arcmin. Image is from Digitized Sky Survey. Click for larger version of the image.
Objects and their data
| NBR | NAME | TYPE | REDSHIFT | MAG | SEPARATION |
| 1 | MCG -07-03-005 | spiral | 0.022592 (6773 km/s) | 14.5 | 0 |
| 2 | PGC 003633 | galaxy | 0.054755 (16415 km/s) | 15.6 (I) | 0.426 |
| 3 | ESP 40160 | galaxy | 0.105483 | 18.60 | 0.948 |
| 4 | ESP 38602 | galaxy | 0.223564 | 19.21 | 2.551 |
| 5 | ESP 38632 | galaxy | 0.115486 | 19.13 | 3.021 |
| 6 | ESP 38526 | galaxy | 0.055215 (16553 km/s) | 19.18 | 3.706 |
| 7 | ESP 40626 | galaxy | 0.053981 (16183 km/s) | 17.33 | 4.657 |
| 8 | ESP 40625 | galaxy | 0.054845 (16442 km/s) | 17.86 | 6.093 |
| 9 | ESP 40187 | galaxy | 0.179334 | 18.29 | 6.479 |
| 10 | ESP 40161 | galaxy | 0.177549 | 18.65 | 6.733 |
| 11 | ESP 38528 | galaxy | 0.055582 (16663 km/s) | 18.84 | 6.858 |
| 12 | ESP 38482 | galaxy | 0.188030 | 19.38 | 6.875 |
| 13 | ESP 38605 | galaxy | 0.176455 | 18.94 | 6.912 |
| 14 | ESP 38669 | galaxy | 0.177936 | 18.99 | 7.119 |
| 15 | ESP 38704 | galaxy | 0.107267 | 19.03 | 7.224 |
| 16 | ESP 38529 | galaxy | 0.054858 (16446 km/s) | 18.84 | 7.258 |
| 17 | ESP 40188 | galaxy | 0.179994 | 18.72 | 7.799 |
| 18 | [VCV2001] J010031.5-401351 | QSO | 0.610000 | 17.90 | 7.958 |
| 19 | LEDA 101141 | E | 0.054948 (16473 km/s) | 16.17 | 7.961 |
| 20 | ESP 38483 | galaxy | 0.159123 | 18.95 | 8.449 |
NED objects within 10′ from AM 0058-402
References
Filed under: DRS
You mean apparent velocity, not radial velocity, right? PGC 003633 isn’t spinning around MCG -07-03-005 that fast
Is there any other information about PGC 003633?
As you can see here, using “radial velocity” for cz is common “therminology”. I’ll see if I can find anything new on the companion.
Of all things, I did not know that was just another term for the implied velocity of the spectrum. Of course, I don’t like the term because it implies something physical that may not be there, but now I’ll understand it when you say it again
I was just wondering whether there was any information on whether the companion is one of the expected young objects (late-type spiral? something without arms of its own yet?) post-ejection or not.
There’s not much information available on the companion. I think it’s all in the NED page of the object. No knowledge of what kind of object it is. With luck there might be a newer and better image of the system somewhere, but I doubt it (see Arp 1980, linked above, for best available image I’m aware of).