| NGC 4365 | |
|---|---|
 NGC 4365 imaged by theVera C. Rubin Observatory | |
| Observation data (J2000epoch) | |
| Constellation | Virgo |
| Right ascension | 12h 24m 28.228s[1] |
| Declination | +07° 19′ 03.07″[1] |
| Redshift | −0.00022±0.00009[2] |
| Heliocentric radial velocity | 1,221 km/s[3] |
| Distance | 74.4 Mly (22.80 Mpc)[3] |
| Apparent magnitude (B) | 11.5[4] |
| Characteristics | |
| Type | E3[5] |
| Other designations | |
| UGC 7488,MCG +01-32-048,PGC 40375[4] | |
NGC 4365 is a giant[6]elliptical galaxy[7] located in theconstellationVirgo. It was discovered by German-English astronomerWilliam Herschel on April 13, 1784.[8][9][10] The galaxy is located at an estimated distance of 74.4 millionlight-years (22.80 Mpc) from theMilky Way galaxy.[3]
NGC 4365 is the central galaxy of the Virgo W' cloud, a sub-group of galaxies about 6 megaparsecs behind (further from us than) theVirgo Supercluster.[6] There is a stream ofglobular clusters connecting NGC 4365 to the neighboring compactlenticular galaxyNGC 4342. It appears that NGC 4365 is stripping globular clusters and stars from its smaller neighbor viatidal interaction.[6]
Themorphological classification of NGC 4365 is E3, indicating a slightly flattenedelliptical galaxy with an ellipticity of 0.26. It has a smooth luminosity profile with no indication of dust arms. There is a shallow cusp at the center.[5] The galaxy has a kinematically distinct core region that is rotating at right angles to the rest of the galaxy, which provides strong evidence for the theory that elliptical galaxies grow through mergers.[11] Most of the galaxy is rotating around themajor axis with the peak velocity reaching around50 km/s, whereas within2″–3″ of the center the peak velocity is80 km/s around theminor axis. This core region is more flattened than the galaxy as a whole,[5] forming a bar-like structure.[11]
The stellar populations of the galaxy suggest it underwent star formation at an early age, with the residual gas being exhausted about 12 billion years ago.[5] In contrast, many of the globular clusters of this galaxy appeared to be of intermediate age of 2–8 billion years old.[12] However, they may instead be of higher than expectedmetallicity.[8][10] The galaxy retains a triaxial structure that has remained largely unchanged for 12 billion years. Becausesupermassive black holes (SMBH) in the centers of galaxies tend to scatter stars into chaotic new orbits, the longevity of NGC 4365's triaxial structure and kinematically distinct stellar populations indicates that it cannot have an SMBH with a mass greater than3×109M☉. TheM–sigma relation predicts a SMBH mass of4×108 M☉ for NGC 4365.[13]
Media related toNGC 4365 at Wikimedia Commons