NGC 474
Galaxy in the constellation Pisces
From Wikipedia, the free encyclopedia
NGC 474 is a large lenticular galaxy in the constellation Pisces. Its velocity with respect to the cosmic microwave background is 2,001±23 km/s, which corresponds to a Hubble distance of 96.2 ± 6.8 Mly (29.51 ± 2.09 Mpc).[1] Additionally, 13 non-redshift measurements give a similar mean distance of 91.50 ± 6.69 Mly (28.054 ± 2.050 Mpc).[5] It was discovered by German-British astronomer William Herschel on 13 December 1784.[6][7]
| NGC 474 | |
|---|---|
NGC 474 imaged by the Hubble Space Telescope | |
| Observation data (J2000[1] epoch) | |
| Constellation | Pisces[2] |
| Right ascension | 01h 20m 06.6862s[1] |
| Declination | +03° 24′ 55.809″[1] |
| Redshift | 0.007722[1] |
| Heliocentric radial velocity | 2315 km/s ±5 km/s[1] |
| Galactocentric velocity | 2398 km/s ±7 km/s[1] |
| Distance | ~100 Mly (~31 Mpc)[2] |
| Apparent magnitude (V) | 12.37[1] |
| Characteristics | |
| Type | S0[3] |
| Size | 250,000 ly (diameter)[4] |
| Apparent size (V) | 7.1′ × 6.3′[1] |
| Other designations | |
| ZWG 385.71, 2MASX J01200669+0324549, Arp 227, UGC 864, MCG +00-04-085, PGC 4801, CGCG 385-071[1][3] | |
NGC 474 is known to possess tidal shells[8] and tidal tails, although their origins remain unclear.[2] One possible explanation is that NGC 474 interacted with a galaxy several billion years ago.[9]
Structure
The origins of the spectacular tidal features around NGC 474 have been extensively studied, and some possible explanations have been published. The authors of one study argued that the tidal tails were formed because of a collision with a galaxy 2 billion years ago.[9] The same study also stated that NGC 474 is absorbing gas from its neighbor, NGC 470, since the ancient collision.[9] In another model, the tidal shells can be explained by a gas-rich spiral galaxy colliding with NGC 474 twice, before finally merging.[8] NGC 474 is moving away from the Sun at a rate of 2412 km/s due to dark energy.[10]
Supernova
See also
Further reading
- Turnbull, A. J.; Carter, D.; Bridges, T. J.; Thomson, R. C. (1999) Shell Formation in NGC474
