| NGC 5252 | |
|---|---|
 NGC 5252 by theHubble Space Telescope | |
| Observation data (J2000epoch) | |
| Constellation | Virgo |
| Right ascension | 13h 38m 15.9s[1] |
| Declination | +04° 32′ 33″[1] |
| Redshift | 0.023093 ± 0.000005[1] |
| Heliocentric radial velocity | 6,923 ± 1km/s[1] |
| Distance | 221Mly (67.9Mpc)[1] 320Mly (98.4Mpc)[2] |
| Apparent magnitude (V) | 13.8 |
| Characteristics | |
| Type | S0[1] |
| Apparent size (V) | 1.4′ × 0.8′[1] |
| Notable features | Seyfert galaxy |
| Other designations | |
| UGC 8622,MCG +01-35-022,PGC 48189[1] | |
NGC 5252 is alenticular galaxy located in the constellationVirgo. It is located at a distance of about 220 to 320 millionlight years from Earth, which, given its apparent dimensions, means that NGC 5252 is about 100,000 light years across.[1] It was discovered byWilliam Herschel on February 2, 1786.[3]
The nucleus of NGC 5252 has been found to beactive and it has been categorised as a type IISeyfert galaxy[4] or type 1.9.[5] A broadH-alpha line has been observed, indicating that a broad line region is partially hidden and the nucleus of NGC 5252 is more active than originally thought.[6]
The most accepted theory for the energy source of active galactic nuclei is the presence of anaccretion disk around asupermassive black hole. The mass of the black hole in the centre of NGC 5252 is estimated to be0.95+1.45
−0.45×109M☉ based on the dynamics of the circumnuclear gas.[7] The mass of the black hole is larger than that observed in Seyfert galaxies and it is more in line with a radio-quietquasar, with a black hole which is accreting at a slow rate.[7] The X-ray observations of the galaxy indicate a flatspectrum with a soft X-rays element due toionised gas cones, which also indicate that the galaxy hosts a quasar relic.[8]
The nucleus is surrounded by filamentary structures which glow green due to the ionised oxygen. These were illuminated when the nucleus of the galaxy hosted a quasar.[9]
Anultraluminous X-ray source has been observed 22 arcseconds from the nucleus of the galaxy, which corresponds to about 10 kiloparsec at the distance of the galaxy. Its luminosity is estimated to be1.5×1040 erg s−1.[2] The source has also been observed in visual light and radiowaves. In radiowaves it features two components, one east and one west.[10] The redshift of the source is similar to that of the galaxy, indicating that it is gravitationally bound to the galaxy.[2] It probably is anintermediate-mass black hole with a mass over104 solar masses, probably the remnant of a nucleus ofdwarf galaxy[2][11] with low-luminosity activity, as the black hole is probably accreting weakly.[12]
