NGC 4197
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| NGC 4197 | |
|---|---|
 NGC 4197 imaged by the Vera C. Rubin Observatory | |
| Observation data (J2000 epoch) | |
| Constellation | Virgo |
| Right ascension | 12h 14m 38.529s[1] |
| Declination | +05° 48′ 19.95″[1] |
| Redshift | 0.006940 ± 0.000013 [1] |
| Heliocentric radial velocity | 2,081 ± 4 km/s[1] |
| Distance | 89.4 ± 12.1 Mly (27.4 ± 3.7 Mpc)[1] |
| Group or cluster | NGC 4261 Group |
| Apparent magnitude (V) | 12.8[2] |
| Characteristics | |
| Type | Scd(f) [1] |
| Size | ~99,000 ly (30.3 kpc) (estimated)[1] |
| Apparent size (V) | 3.23′ × 0.57′ [1] |
| Other designations | |
| IRAS 12121+0605, UGC 7247, MCG +01-31-029, PGC 39114, CGCG 041-052, VV 520[1] | |
NGC 4197 is a spiral galaxy in the constellation Virgo. The galaxy lies about 90 million light years away from Earth, which means, given its apparent dimensions, that NGC 4197 is approximately 100,000 light years across.[1] It was discovered by William Herschel on April 13, 1784.[3]
NGC 4197 is a spiral galaxy seen nearly edge-on, at an angle of 79°. Two faint plumes are visible in H-alpha in the galactic halo southeast of the galaxy, extending for about 5 kiloparsec. The observed plumes are probably associated with HII regions in the disk. About 13% of the H-alpha emission of the galaxy comes from extraplanar gas, with an estimated mass of 1.0×108 M☉.[4] The star formation rate of the galaxy is estimated to be about 1 M☉ per year.[5]
A strong point-like X-ray source has been detected at the centre of the galaxy, lying 0.7 arcseconds from the nucleus as reported in the red band of the Sloan Digital Sky Survey. Its spectrum is well described by a power law with an absorption element. The X-ray luminosity is estimated to be 1.4+0.7
−0.3×1040 erg/s. The source of the X-rays could be a black hole in the nucleus or a stellar mass ultraluminous X-ray source.[6] The mass of the central black hole is estimated to be 2×105 M☉ based on the spiral pitch angle and 7×104 M☉ based on the stellar mass.[7]
