| NGC 3657 | |
|---|---|
 SDSS image of NGC 3657. | |
| Observation data (2000.0epoch) | |
| Constellation | Ursa Major |
| Right ascension | 11h 23m 55.6s[1] |
| Declination | 52° 55′ 15″[1] |
| Redshift | 0.004059[1] |
| Heliocentric radial velocity | 1217km/s[1] |
| Distance | 63 Mly (19.2 Mpc)[1] |
| Apparent magnitude (V) | 13.5[1] |
| Absolute magnitude (B) | -21.23[1] |
| Characteristics | |
| Type | SAB(rs)c pec[1] |
| Mass | 4.6×109 (Stellar mass)[2] M☉ |
| Size | ~136,600 ly (41.88 kpc) (estimated)[1] |
| Apparent size (V) | 1.03 × 0.79[1] |
| Other designations | |
| UGC 06406, CGCG 268-030, MCG +09-19-065, PGC 035002[1] | |
NGC 3657 is apeculiarspiral galaxy located approximately 63 millionlight-years away[3] in the constellationUrsa Major. It was discovered April 12, 1789 byWilliam Herschel.[4] NGC 3657 is a member of theNGC 3631 Group[5][6][7] which is part of theUrsa Major Cloud.[5][8]
NGC 3657 has a huge ultraviolet extended disk revealed by theGALEX space telescope which suggests that NGC 3657 contains an extendedHI reservoir. The galaxy has an unusually low ratio of the mass ofdust (Mdust) to the mass of neutral atomic hydrogen (MHI) with its extendedHI reservoir wherestar formation is not observed. This indicates that NGC 3657 has either only recently accreted gas from the outside environment or the HI gas in the galaxy has insufficient density to collapse and form stars.[9]
The galaxy hosts asupermassive black hole with an estimated mass of 4.3 × 106M☉.[10]
Media related toNGC 3657 at Wikimedia Commons