| NGC 185 | |
|---|---|
.jpg) NGC 185 imaged by theHubble Space Telescope | |
| Observation data (J2000.0[1]epoch) | |
| Constellation | Cassiopeia |
| Right ascension | 00h 38m 57.970s[1] |
| Declination | +48° 20′ 14.56″[1] |
| Redshift | −202 ± 3km/s[2] |
| Distance | 2.05 ± 0.13Mly (630 ± 40kpc)[3][4][5][a] |
| Apparent magnitude (V) | 10.1[2] |
| Characteristics | |
| Type | dSph/dE3,[2] Sy2[1] |
| Apparent size (V) | 11.7′ × 10.0′[2] |
| Notable features | Satellite galaxy of the Andromeda Galaxy |
| Other designations | |
| UGC 396,[2]PGC 2329,[2] LEDA 2329,[1]Caldwell 18 | |
NGC 185 (also known asCaldwell 18) is adwarf spheroidal galaxy located2.08 millionlight-years from Earth, appearing in theconstellationCassiopeia. It is a member of theLocal Group, and is asatellite of theAndromeda Galaxy (M31).[6] NGC 185 was discovered byWilliam Herschel on November 30, 1787, and he cataloged it "H II.707".[6]John Herschel observed the object again in 1833 when he cataloged it as "h 35", and then in 1864 when he cataloged it as "GC 90" within hisGeneral Catalogue of Nebulae and Clusters.[6] NGC 185 was first photographed between 1898 and 1900 byJames Edward Keeler with theCrossley Reflector ofLick Observatory.[6] Unlike most dwarf elliptical galaxies, NGC 185 contains youngstellar clusters, and star formation proceeded at a low rate until the recent past. NGC 185 has anactive galactic nucleus (AGN) and is usually classified as a Type IISeyfert galaxy,[7] though its status as a Seyfert is questioned.[8] It is possibly the closest Seyfert galaxy to Earth, and is the only known Seyfert in the Local Group.
At least two techniques have been used to measure distances to NGC 185. The surface brightness fluctuations distance measurement technique estimates distances to galaxies based on the graininess of their appearance. The distance measured to NGC 185 using this technique is 2.08 ± 0.15Mly (640 ± 50kpc).[3] However, NGC 185 is close enough that thetip of the red giant branch (TRGB) method may be used to estimate its distance. The estimated distance to NGC 185 using this technique is 2.02 ± 0.2 Mly (620 ± 60 kpc).[4][5]
Martínez-Delgado, Aparicio, & Gallart (1999) looked into thestar formation history of NGC 185 and found that the majority of star formation in NGC 185 happened at early times.[8] In the last ~1 Gyr, stars have formed only near the center of this galaxy.Walter Baade discovered young blue objects within this galaxy in 1951, but these have turned out to be star clusters and not individual stars. Asupernova remnant near the center was also discovered by Martínez-Delgado et al.[9]
| Location | Andromeda Galaxy → Andromeda subgroup →Local Group →Local Sheet →Local Volume →Virgo Supercluster →Laniakea Supercluster →Pisces–Cetus Supercluster Complex →Local Hole →Observable universe →Universe Each → may be read as "within" or "part of". | .jpg) |
|---|---|---|
| Satellite galaxies |
*It is uncertain whether these are companion galaxies of the Andromeda Galaxy | |
| Catalogued stars | ||
| Other | ||
| Stars |
| ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| |||||||||||||
| Star clusters |
| ||||||||||||
| Nebulae |
| ||||||||||||
| Galaxies |
| ||||||||||||
| |||||||||||||
