NGC 4491 is a dwarf barred spiral galaxy[2] located about 55 million light-years away[3] in the constellation Virgo.[4] NGC 4491 was discovered by astronomer William Herschel on March 15, 1784.[5] NGC 4491 is located in a subgroup of the Virgo Cluster centered on Messier 87 known as the Virgo A subgroup.[2]
| NGC 4491 | |
|---|---|
 SDSS image of NGC 4491. | |
| Observation data (J2000 epoch) | |
| Constellation | Virgo |
| Right ascension | 12h 30m 57.1s[1] |
| Declination | 11° 29′ 01″[1] |
| Redshift | 0.001658/497 km/s[1] |
| Distance | 55,420,000 ly[2] |
| Group or cluster | Virgo Cluster |
| Apparent magnitude (V) | 13.5[1] |
| Characteristics | |
| Type | SB(s)a[1] |
| Size | ~7,140 ly (estimated)[1] |
| Apparent size (V) | 1.7 x 0.9[1] |
| Other designations | |
| PGC 41376, UGC 7657, VCC 1326[1] | |
Tidal interactions
editNGC 4491 is a strongly barred galaxy. The bar may have grown from the tidal influence of other galaxies in the Virgo Cluster.[2]
Possible Seyfert activity
editThe infrared-radio properties of NGC 4491 possibly suggest the presence of an AGN in the galaxy. However, spectral analysis of the galaxy does not support this view since emission lines are absent or very weak and narrow.[2]
See also
editReferences
edit- ^ a b c d e f g h "NASA/IPAC Extragalactic Database". Results for NGC 4491. Retrieved 2017-10-21.
- ^ a b c d e Roussel, H.; Helou, G.; Beck, R.; Condon, J. J.; Bosma, A.; Matthews, K.; Jarrett, T. H. (2 May 2003). "Nascent Starbursts in Synchrotron‐deficient Galaxies with Hot Dust". The Astrophysical Journal. 593 (2): 733–759. arXiv:astro-ph/0305046. Bibcode:2003ApJ...593..733R. doi:10.1086/376691. S2CID 122402426.
- ^ "Your NED Search Results". ned.ipac.caltech.edu. Retrieved 2017-10-22.
- ^ Rojas, Sebastián García. "Galaxy NGC 4491 - Barred Spiral Galaxy in Virgo Constellation · Deep Sky Objects Browser". DSO Browser. Retrieved 2017-10-22.
- ^ "New General Catalog Objects: NGC 4450 - 4499". cseligman.com. Retrieved 2017-10-08.
External links
edit
Wikimedia Commons has media related to NGC 4491.
- NGC 4491 on WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Articles and images