NGC 4889

Coma B

The elliptical galaxy NGC 4889
Credit: Hubble Space Telescope
Observation data Epoch J2000.0
Constellation	Coma Berenices
Right ascension	13h 00m 08.1s
Declination	+27° 58′ 37″
Apparent dimension (V)	2.9' × 1.9'
Apparent magnitude (V)	12.9
Characteristics
Type	cD; E4; Dd
Astrometry
Heliocentric radial velocity	6495 ± 13km/s
Redshift	0.021665
Galactocentric velocity	6509 ± 13km/s
Distance	308 ± 3 Mly (94.43 ± 0.92 Mpc)
Other designations
Coma B, NGC 4884, UGC 8110, MCG 5-31-77, PGC 44715, ZWG 160.241, DRCG 27-148, Caldwell 35
Database references
SIMBAD	data
See also: Galaxy, List of galaxies

NGC 4889 (also known as Caldwell 35, Coma B) is a class-4 supergiant elliptical galaxy. It was discovered in 1785 by the British astronomer Frederick William Herschel I, who catalogued it as a bright, nebulous patch. The brightest galaxy within the northern Coma Cluster, it is located at a distance of 94 million parsecs (308 million light years) from Earth. Unlike a flattened, disc-shaped spiral galaxy like the Milky Way, NGC 4889 has no visible dust lanes or spiral arms and has a smooth, featureless, egg-shaped profile that diminishes in luminosity with distance from the center. At the core of the galaxy is a supermassive black hole that heats the intracluster medium through the action of friction from infalling gases and dust. The X-ray emission from the galaxy extends out to several million light years of the cluster.

As with other similar elliptical galaxies, only a fraction of the mass of NGC 4889 is in the form of stars. They have a flattened, unequal distribution that bulges within its edge. Between the stars is a dense interstellar medium full of heavy elements emitted by evolved stars. The diffuse stellar halo extends out to one million light years in diameter. Orbiting the galaxy is a very large population of globular clusters. NGC 4889 is also a strong source of soft X-ray, ultraviolet, and radio frequency radiation.

As the largest and the most massive galaxy easily visible to Earth, NGC 4889 has played an important role in both amateur and professional astronomy, and has become a prototype in studying the dynamical evolution of other supergiant elliptical galaxies in the more distant universe.

NGC 4889 was not included by the astronomer Charles Messier in his famous Messier catalogue despite being an intrinsically bright object quite close to some Messier objects. The first known observation of NGC 4889 was that of Frederick William Herschel I, assisted by his sister, Caroline Lucretia Herschel, in 1785, who included it in the Catalogue of Nebulae and Clusters of Stars published a year later. In 1864, Herschel's son, John Frederick William Herschel, published the General Catalogue of Nebulae and Clusters of Stars. He included the objects catalogued by his father, including the one later to be called NGC 4889, plus others he found that were somehow missed by his father.