| ESO 444-46 | |
|---|---|
 HST image of the elliptical galaxy ESO 444-46. | |
| Observation data (J2000epoch) | |
| Constellation | Centaurus |
| Right ascension | 13h 27m 56.9ss[1] |
| Declination | −31° 29′ 44″[1] |
| Redshift | 0.046902±0.000070[1] |
| Heliocentric radial velocity | 14,061±21 km/s[1] |
| Galactocentric velocity | 13,921±22 km/s[1] |
| Distance | 654.9 ± 45.99 Mly (200.8 ± 14.1 Mpc)h−1 0.6774 (Comoving)[1] 667 Mly (204.5 Mpc)h−1 0.6774 (Light-travel) |
| Group orcluster | Abell 3558 |
| Apparent magnitude (V) | 12.6[1] |
| Characteristics | |
| Type | cD;E+4;BrClG[1] |
| Size | 670,710 ly × 382,320 ly (205.64 kpc × 117.22 kpc) (diameter; 27.0 B-mag arcsec−2)[1][a] 450,940 ly × 315,650 ly (138.26 kpc × 96.78 kpc) (diameter; "total" magnitude)[1][a] |
| Apparent size (V) | 1.7′ × 1.2′[1] |
| Notable features | Large globular cluster population |
| Other designations | |
| ESO 444- G 046,[1] MCG −05-32-026,[1] PGC 047202,[1] Shapley 8-1[1] | |
ESO 444-46 (Shapley 8-1,A3558-M1) is a class E4supergiantelliptical galaxy;[2] the dominant and brightest member of the Abell 3558galaxy cluster around 200.8megaparsecs (654.9 millionlight-years) away in theconstellationCentaurus.[2][3][4][1] It lies within the core of the massiveShapley Supercluster, one of the closest neighboringsuperclusters.[5] It is one of thelargest galaxies in thelocal universe, and possibly contains one of themost massive black holes known. Theblack hole's mass is very uncertain, with estimates ranging from as low as 501 million M☉, to as high as 77.6 billion M☉.[6][7]
ESO 444-46 has an estimated population of about 27,000globular clusters which may be one of the largest populations ever studied. This is in contrast to 15,000 globular clusters inMessier 87, and 200 in theMilky Way. However, this large number may be due to the addition ofIntracluster globular clusters since the galaxy lies about 1 arcmin of the center of Abell 3558.[8]
A calculation using the spheroidal luminosity method by estimating the stellar density of the central region using its brightness, yielded a mass of 77.6 billion solar masses (with the range being 22 billion M☉ to 270 billion M☉).[6][7] This would make it one of themost massive black holes known – nearly twelve times the mass of the black hole in Messier 87, and 18,000 times more massive thanSagittarius A*, the Milky Way's central black hole. A black hole of this mass has aSchwarzschild radius of 1,530AU (about 461 billion km in diameter).
Alternative calculations using theM-sigma relation and the newer core break radius method yielded estimates of 500 million M☉ and 27 billion M☉, respectively.[6][7]
