NGC 5238
| NGC 5238 | |
|---|---|
Hubble image of NGC 5238
|
|
| Observation data (J2000 epoch) | |
| Constellation | Canes Venatici |
| Right ascension | 13h 34m 43.8s |
| Declination | +51° 36′ 33″ |
| Redshift | 0.0015 |
| Helio radial velocity | 229 km/s |
| Distance (comoving) | 4.51 Mpc |
| Characteristics | |
| Type | Irr |
| Mass | 1.17×106M☉ |
| Mass/Light ratio | 0.6M☉/L☉ |
| Apparent size (V) | 64.4" |
| Other designations | |
| UGC 8565, VV 828, Mrk 1479, SBS 1332+518, I Zw 64, KPG 384 | |
NGC 5238 is an irregular galaxy in the constellation Canes Venatici. Located at a comoving distance of 4.51 Mpc, it is 64.4 arcseconds in diameter. It has sometimes been classified as a blue compact dwarf galaxy. Although some authors have hypothesized it to be a member of the M101 Group of galaxies, it is currently believed to be an isolated galaxy.
At an inclination of 39° with respect to Earth, NGC 5238 has a total mass of 117 million solar masses, with a star formation rate of 0.01 solar masses per year. Of the total mass, HI gas appears to account for 26 million solar masses.
In 1977, NGC 5238 was hypothesized to not be a single galaxy, but rather a pair of interacting galaxies. It was not until ten years later that a dedicated study of the galaxy's rotation curve was undertaken, showing that the galaxy is indeed a single galaxy. One of the two regions that was thought to be the nucleus of a galaxy was instead shown to be simply a large HII region around 100 pc in diameter.
The morphological type of NGC 5238 has been the subject of some controversy. In 1979, the galaxy was classified as a barred spiral galaxy. Soon after, in 1984, the galaxy was included in a study of blue compact dwarf galaxies, incompatible with the classification of a barred spiral. However, the barred spiral classification was considered the correct classification for years. It was not until the mid 1990s that the galaxy was first recognized as a dwarf irregular galaxy. Even after this, the majority of studies recognized the galaxy as a spiral galaxy until 2015, when the classification of irregular finally became widely accepted
As it appears to us, NGC 5238 is tilted at an inclination of 39°. This 2013 estimate follows previous estimates of 30° in 1987, 37 ± 5° in 1992, and 47° in 1999 In the Spitzer 3.6 µm band, the semimajor axis of its angular size is 64.4", with an ellipticity of 0.201.
...
Wikipedia