| ESO 383-G 076 | |
|---|---|
 Image by the DESI Legacy Imaging Surveys, Data Release 10. | |
| Observation data (J2000.0epoch) | |
| Constellation | Centaurus |
| Right ascension | 13h 47m 28.38s[1] |
| Declination | −32° 51′ 53.9″[1] |
| Redshift | 0.03858±0.00003[1] |
| Heliocentric radial velocity | 11,567±9.3 km/s[1] |
| Galactocentric velocity | 11435±11 km/s[1] |
| Distance | 200.59 ± 14.12megaparsecs (654.2 ± 46.05 millionlight-years)h−1 0.6774[1][a] |
| Group orcluster | Abell 3571 |
| Apparent magnitude (V) | 11.252 |
| Characteristics | |
| Type | cD5; E5;BrClG[1] |
| Mass | 2.15×1012[2] M☉ |
| Size | 540.9kiloparsecs (1,800,000light-years) (diameter; 90% total B-light)[1] 136.9kiloparsecs (447,000light-years) (diameter; 25.0 mag/arcsec2 B-band isophote)[b] |
| Notable features | Supergiant elliptical galaxy; luminous X-ray source |
| Other designations | |
| ESO 383- G 076; ESO 134436-3237.0; AM 1344-323; MCG -05-33-002; WISEA J134728.38-325154.0; 2MASX J13472838-3251540; 2MASS J13472837-3251536; PGC 48896Abell 3571 001; Abell 3571 BCG; Abell 3571 cD | |
ESO 383-76 (ESO 383-G 076) is an elongated, X-ray luminoussupergiant elliptical galaxy, residing as the dominant,brightest cluster galaxy (BCG) of theAbell 3571galaxy cluster, the sixth-brightest in the sky at X-ray wavelengths.[3] It is located at the distance of 200.6megaparsecs (654 millionlight-years) from Earth, and is possibly a member of the largeShapley Supercluster. With a diameter of about 540.9 kiloparsecs (1.8 million light-years), it is one of thelargest galaxies known. It also contains asupermassive black hole, one of themost massive known with mass estimates varying from 2 billion M☉ to 28 billion M☉.[4][5]
The first known observation of the galaxy was during the creation of theMorphological Catalogue of Galaxies byBoris Vorontsov-Velyaminov and V.P. Harkipova in 1974,[6] with the catalogue entryMCG-05-33-002. The galaxy was also observed around this time by theESO Sky Survey Atlas, a large-scale survey of the Southern Sky conducted using the 1-metreSchmidt telescope inLa Silla Observatory. In 1982, the ESO/Uppsala Catalogue then lists the galaxy in its current designation form – ESO 383-G 076, indicating both its field number (field 383 out of the 606 in the survey), classification (G, for "Galaxy"), and its numerical identifier in its field.[7] The galaxy, at this point, was nothing more than just an obscure catalogue entry.
O.G. Richter in 1984 then observed the galaxy during a redshift survey of the ESO/SRC Survey Fields 444 and 445 of the Klemola 27 group (now known as theIC 4329 galaxy group).[8] The group consists of prominent galaxies such as the namesake IC 4329 – another massive supergiant elliptical that is also an extremeSeyfert galaxy, andNGC 5291 – a disturbedinteracting galaxy pair.[8] ESO 383-76, initially thought to be a member of this group, was listed as the 442nd galaxy in Richter's table entry and has been given the morphology E/S0 (either anelliptical orlenticular galaxy).[8] The galaxy has also been included in the Southern Galaxy Catalogue, containing nearly 5,000 galaxies, compiled in 1985 by the husband-and-wife astrophysicistsGérard andAntoinette de Vaucouleurs, along with H.G. Corwin Jr.[9]
ESO 383-76 would be additionally recorded in many subsequent galaxy surveys, such as the survey of theHydra–Centaurus Supercluster by L.N. da Costaet al in 1986,[10] and moreover a photometric catalogue by Lauberts and Valentijn in 1989 that made the first angular diameter measurements of the galaxy.[11] This includes the D25 and D25.5 B-band isophotes, as well as the 50% total light emission (thehalf-light radius) and variations of it (60%, 70%, and 90%). A.P. Fairallet al would further incorporate the galaxy in their wide-scale survey of the Hydra-Centaurus Supercluster in 1989.[12] It was additionally included in many other surveys due to its location in the sky in the rich Centaurus region and the wide-scale research of extragalactic objects near the Milky Way plane by the last decade of the 20th century. The galaxy has additionally been catalogued byAlan Dressler in 1991 during an analysis of velocities of 1,314 galaxies near theMilky Way galactic plane region – allowing to pinpoint the location and verify the existence of theGreat Attractor.[13]
ESO 383-76 is a supergiant elliptical galaxy (type-cD galaxy) of an advanced Hubble morphology (E5, with E0 being spherical and E7 being flattened), with its major axis being more than twice the length of its minor axis. The galaxy is a very luminous source ofX-rays, and is the sixth-brightest X-ray source in the sky.[3]
In an analysis of the cluster A3571 by H. Quintana and R. de Souza in 1994, ESO 383-76 has been noted to have a very elongated shape with a diffuse halo extending throughout the cluster, suggesting that the galaxy had formed very early during the formation of Abell 3571 and it retains the original imprint of its collapsing cloud.[14] The mass of the core region, which also includes the galaxy, is on the order of2.15×1012 M☉.[2]
There are various methods used in astronomy in defining the size of a galaxy, and each of them can yield different results with respect to the other. This is usually affected by exposure time, the wavelength used, and the instrument being used.
One method that is commonly used in the astronomical literature is thegalaxy effective radius where 50% of the total galaxy's light was emitted; variations of 60%, 70%, and 90% are also used. An estimation of the galaxy's size by the ESO/Uppsala catalogue's broad-band photographic plates in 1989 using the 90% total light definition yield a very large apparent diameter of 555.9 arcseconds (about 9.25 arcminutes; 27% the width of thefull moon in the sky), which using the currently accepted distance to the galaxy yield a diameter of 540.9 kiloparsecs (1,800,000 light-years).[15] This makes it one of the largest physical diameter measurements of any galaxy known – 20 times that of theMilky Way's diameter,[16][17] and 3.5 times that of the maximum estimated diameter ofIC 1101.[18]
Alternative measurements from the same study using other methods (such as the D25 isophote) yield diameters as small as 139.04 kiloparsecs (453,000 light-years), with various estimates in between depending on the measurement.[15] In a study in 1994, the halo of the galaxy (defined as the brightness at 2σ above background) has a diameter of about 600 kiloparsecs (2 million light-years). The paper states that this is on the scale of the distance between the Milky Way and Andromeda galaxies. The halo extends throughout a large part of Abell 3571.[2]
ESO 383-76 lies at the center of the Abell 3571 galaxy cluster, which is a possible member of theShapley Supercluster (or alternatively the Shapley 8 Concentration – an outlying structure).[3] This massive supercluster hosts many clusters with similar supergiant elliptical galaxies, among themESO 444-46.
