Arp 70 / PGC 5085 and 212740
| Designation(s) | Arp 70, PGC 5085, PGC 212740 |
| Object Type(s) | Galaxy, Galaxy Cluster |
| Relevant Catalog(s) | All (Chron), Arp |
| Arp Category | Spiral galaxies with small high surface brightness companions on arms |
| Obs. Lat/Long | 42° 17', 073° 57' |
| Constellation | Pisces |
| Date and Time Observed | 2025-08-28 01:05:00 |
| Instrument | EdgeHD 8" w/f7 reducer-1,422mm FL |
| Camera | Player One Apollo-M Mini |
| Image Details | Up is 182.6 degrees E of N. Transparency: Excellent. Seeing: Good. Total integration time was 60m 15s. Exposures 15s@300g, No Filter. Dithered and recentered in SharpCap. No guiding. |
| Description | The Arp image shows faint dust lanes "nearly" connecting the larger galaxy (PGC 5085 or Arp 70b) and the smaller one (Arp 70a or PGC 212740). Frankly I struggled to reproduce the dust lanes, in part because my camera was rendering not a wisp of dust, but an extended arm connecting the two galaxies. It's clearer in the positive image. This is another case where a modern CMOS camera on an 8" telescope delivers "deeper" imagery than the best telescope in the world from 1966. A 2020 study conclude: "Arp 70b is an interacting galaxy where we have found two large-scale outflows currently taking place, one of them in the centre of the galaxy and the other associated with a giant H ii region in the arm, close to the centre itself". Surprising to me, the matter is flowing from the larger galaxy to the smaller. [Citation: A Camps-Fariña, J E Beckman, J Font, I del Moral-Castro, S F Sanchez, A Borlaff, Arp 70: an interacting galaxy with extreme outflows, Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 1, March 2020, Pages 1434–1446, https://doi.org/10.1093/mnras/staa347] |
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