NGC 4203
| NGC 4203 | |
|---|---|
| Observation data (J2000 epoch) | |
| Constellation | Coma Berenices |
| Right ascension | 12h 15m 05.0s[1] |
| Declination | +33° 11′ 50″[1] |
| Redshift | 0.003620[2] |
| Helio radial velocity | 1,083[3] km/s |
| Galactocentric velocity | 1,093[3] km/s |
| Distance | 49.84 ± 0.46 Mly (15.28 ± 0.14 Mpc)[3] |
| Type | SAB0−[4] |
| Apparent dimensions (V) | 2.467′ × 2.319′[5] |
| Apparent magnitude (V) | 11.99[6] |
| Apparent magnitude (B) | 12.98[6] |
| Other designations | |
| 2MASX J12150502+3311500, LEDA 39158, UGC 7256, UZC J121505.0+331152, Z 187-29 .[7] | |
NGC 4203 is the New General Catalogue identifier for a lenticular galaxy in the northern constellation of Coma Berenices. It was discovered on March 20, 1787 by English astronomer William Herschel,[8] and is situated 5.5° to the northwest of the 4th magnitude star Gamma Comae Berenices and can be viewed with a small telescope.[9] The morphological classification of NGC 4203 is SAB0−,[4] indicating that it has a lenticular form with tightly wound spiral arms and a weak bar structure at the nucleus.[10]
This galaxy has a fairly large reservoir of neutral hydrogen containing on the order of a billion solar masses (M☉), but it is only undergoing a low rate of new star formation. Hence, the inner star formation of the galaxy is fairly old; roughly ten billion years on average. The neutral hydrogen is arranged in two ring-like structures, with the outer ring having nine times the mass of the inner. In the central region there is around 2.5×107 M☉ of molecular hydrogen, plus dust structures within 980 ly (300 pc) of the nucleus. The gas in the outer disk may have been accreted from the inter-galactic medium, or captured during a close encounter with a dwarf galaxy.[11]
The nucleus of the galaxy contains a low-ionization nuclear emission-line region of type 1.9. This is being generated by a supermassive black hole of an estimated (6±1)×107 M☉. An influx of gas of around 2×10−2 M☉/yr is sufficient to explain the measured X-ray luminosity. The time-varying emissions from the region are perhaps best explained by an infalling asymptotic giant branch star that is losing mass to the black hole along a contrail.[12]
References
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