| NGC 3945 | |
|---|---|
 Hubble Space Telescope image of NGC 3945 | |
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 11h 53m 13.726s[1] |
| Declination | +60° 40′ 32.02″[1] |
| Redshift | 0.004153[2] |
| Heliocentric radial velocity | 1242 ± 22 km/s[2] |
| Distance | 63 Mly (19.4 Mpc)[3] |
| Apparent magnitude (V) | 10.75[4] |
| Apparent magnitude (B) | 11.70[4] |
| Characteristics | |
| Type | (R)SB(rs)0+[3] |
| Other designations | |
| UGC 6860, MCG +10-17-096, PGC 37258[2] | |
NGC 3945 is a barred lenticular galaxy in the constellation Ursa Major. It was discovered on March 19, 1790, by the astronomer William Herschel.[5]
NGC 3945 has a complex structure, with two concentric bars and a pseudobulge.[3] Unlike classical bulges which are like miniature elliptical galaxies, pseudobulges have features similar to disk galaxies, including a flattened structure and significant rotation.[6] It is classified as a LINER galaxy.[3] The formation history of NGC 3945 is likely quite complex, with the pseudo-bulge being formed gradually from disk material, while bulges (spheroidal components) would have formed from violent merger events.[3]
Unlike galaxies with similar velocity dispersions and luminosities, the central black hole of NGC 3945 has an unusually low mass, estimated to be around 9×106 M☉. However, it is also possible that NGC 3945 has no central black hole at all.[7]
- ^ a b Skrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN 0004-6256. S2CID 18913331.
- ^ a b c "NGC 3945". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-05-18.
- ^ a b c d e Dullo, Bililign T.; Martínez-Lombilla, Cristina; Knapen, Johan H. (2016). "Complex central structures suggest complex evolutionary paths for barred S0 galaxies". Monthly Notices of the Royal Astronomical Society. 462 (4): 3800–3811. arXiv:1608.03539. doi:10.1093/mnras/stw1868.
- ^ a b "Search specification: NGC 3945". HyperLeda. Université Claude Bernard Lyon 1. Retrieved 2021-05-18.
- ^ Seligman, Courtney. "New General Catalogue objects: NGC 3900 - 3949". cseligman.com. Retrieved 2021-05-18.
- ^ Fisher, David B.; Drory, Niv (2008). "The Structure of Classical Bulges and Pseudobulges: The Link Between Pseudobulges and Sérsic Index". The Astronomical Journal. 136 (2): 773–839. arXiv:0805.4206. Bibcode:2008AJ....136..773F. doi:10.1088/0004-6256/136/2/773. S2CID 16126374.
- ^ Gültekin, Kayhan; Richstone, Douglas O.; Gebhardt, Karl; Lauer, Tod R.; Pinkney, Jason; Aller, M. C.; Bender, Ralf; Dressler, Alan; Faber, S. M.; Filippenko, Alexei V.; Green, Richard; Ho, Luis C.; Kormendy, John; Siopis, Christos (2009). "A Quintet of Black Hole Mass Determinations". The Astrophysical Journal. 695 (2): 1577–1590. arXiv:0901.4162. Bibcode:2009ApJ...695.1577G. doi:10.1088/0004-637X/695/2/1577. S2CID 14365610.