NGC 3945
| NGC 3945 | |
|---|---|
NGC 3945 imaged by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major |
| Right ascension | 11h 53m 13.726s |
| Declination | +60° 40′ 32.02″ |
| Redshift | 0.004153 |
| Heliocentric radial velocity | 1242 ± 22 km/s |
| Distance | 63 Mly (19.4 Mpc) |
| Group or cluster | NGC 4036 Group (LGG 266) |
| Apparent magnitude (V) | 10.75 |
| Apparent magnitude (B) | 11.70 |
| Characteristics | |
| Type | (R)SB(rs)0+ |
| Size | ~128,800 ly (39.48 kpc) (estimated) |
| Apparent size (V) | 5.2′ × 3.5′ |
| Other designations | |
| IRAS 11506+6056, UGC 6860, MCG +10-17-096, PGC 37258, CGCG 292-042 | |
NGC 3945 is a barred lenticular galaxy in the constellation Ursa Major. It was discovered by German-British astronomer William Herschel on March 19, 1790.
NGC 3945 has a complex structure, with two concentric bars and a pseudobulge. Unlike classical bulges which are like miniature elliptical galaxies, pseudobulges have features similar to disk galaxies, including a flattened structure and significant rotation. It is classified as a LINER galaxy. 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.
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.