NGC 4639 | |
---|---|
Observation data ( J2000 epoch) | |
Constellation | Virgo |
Right ascension | 12h 42m 52.37814s [2] |
Declination | +13° 15′ 26.7129″ [2] |
Heliocentric radial velocity | 989 km/s [3] |
Distance | 72.02 ± 0.23 Mly (22.08 ± 0.07 Mpc) [3] |
Group or cluster | Virgo Cluster |
Apparent magnitude (V) | 12.2 [4] |
Characteristics | |
Type | SAB(rs)bc [5] |
Apparent size (V) | 2′.8 × 1′.9 [4] |
Notable features | Seyfert type 1 |
Other designations | |
IRAS 12403+1331, LEDA 42741, MCG+02-32-189, NGC 4639, UGC 7884, VCC 1943, [6] PGC 42741 [4] |
NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast". [7] This is a relatively nearby galaxy, [8] lying approximately 72 million light-years away from the Milky Way. [3] It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago. [9] NGC 4639 is a member of the Virgo Cluster. [10]
The morphological classification of this galaxy is SAB(rs)bc, [5] indicating a spiral galaxy with a weak bar (SAB), an incomplete ring around the bar (rs), and moderate to loosely-wound spiral arms (bc). NGC 4639 has a mildly active galactic nucleus of the Seyfert type 1; one of the weakest known. The compact central source has been detected by its X-ray emission, and is variable on timescales of months to years. [8] There is a supermassive black hole at the core [11] with an estimated mass of 7.9×106 M☉. [12]
Two supernovae have been observed in NGC 4639. The classical Type Ia Supernova SN 1990N was discovered in this galaxy on June 22, 1990, two weeks before reaching peak brightness. [13] It was positioned 63.2 ″ east and 1.8″ south of the galaxy core. [14] The brightness and proximity of this supernova event has allowed it to be used as a standard candle. [13] SN 2018imf ( type IIP, mag. 15.7) was discovered on 14 November, 2018. [15]
NGC 4639 | |
---|---|
Observation data ( J2000 epoch) | |
Constellation | Virgo |
Right ascension | 12h 42m 52.37814s [2] |
Declination | +13° 15′ 26.7129″ [2] |
Heliocentric radial velocity | 989 km/s [3] |
Distance | 72.02 ± 0.23 Mly (22.08 ± 0.07 Mpc) [3] |
Group or cluster | Virgo Cluster |
Apparent magnitude (V) | 12.2 [4] |
Characteristics | |
Type | SAB(rs)bc [5] |
Apparent size (V) | 2′.8 × 1′.9 [4] |
Notable features | Seyfert type 1 |
Other designations | |
IRAS 12403+1331, LEDA 42741, MCG+02-32-189, NGC 4639, UGC 7884, VCC 1943, [6] PGC 42741 [4] |
NGC 4639 is a barred spiral galaxy located in the equatorial constellation of Virgo. It was discovered by German-born astronomer William Herschel on April 12, 1784. John L. E. Dreyer described it as "pretty bright, small, extended, mottled but not resolved, 12th magnitude star 1 arcmin to southeast". [7] This is a relatively nearby galaxy, [8] lying approximately 72 million light-years away from the Milky Way. [3] It is a companion to NGC 4654, and the two appear to have interacted roughly 500 million years ago. [9] NGC 4639 is a member of the Virgo Cluster. [10]
The morphological classification of this galaxy is SAB(rs)bc, [5] indicating a spiral galaxy with a weak bar (SAB), an incomplete ring around the bar (rs), and moderate to loosely-wound spiral arms (bc). NGC 4639 has a mildly active galactic nucleus of the Seyfert type 1; one of the weakest known. The compact central source has been detected by its X-ray emission, and is variable on timescales of months to years. [8] There is a supermassive black hole at the core [11] with an estimated mass of 7.9×106 M☉. [12]
Two supernovae have been observed in NGC 4639. The classical Type Ia Supernova SN 1990N was discovered in this galaxy on June 22, 1990, two weeks before reaching peak brightness. [13] It was positioned 63.2 ″ east and 1.8″ south of the galaxy core. [14] The brightness and proximity of this supernova event has allowed it to be used as a standard candle. [13] SN 2018imf ( type IIP, mag. 15.7) was discovered on 14 November, 2018. [15]