| NGC 7421 | |
|---|---|
 Legacy Surveys DR10 image of NGC 7421 | |
| Observation data (J2000epoch) | |
| Constellation | Grus |
| Right ascension | 22h 56m 54.353s[1] |
| Declination | −37° 20′ 50.44″[1] |
| Distance | 81.6 Mly (25.01 Mpc)[2] |
| Apparent magnitude (V) | 12.0[3] |
| Characteristics | |
| Type | SB(rs)bc[4] |
| Mass | 20.9×109[5] M☉ |
| Apparent size (V) | 2.2′[3] |
| Other designations | |
| NGC 7421,LEDA 70083,MCG -06-50-015[6] | |
NGC 7421 is abarred spiral galaxy in the southernconstellation ofGrus. It was discovered by English astronomerJohn Herschel on August 30, 1834.[7] In Danish astronomerJ. L. E. Dreyer'sNew General Catalogue of Nebulae and Clusters of Stars it was described as: considerably bright, large, very little extended, gradually pretty much brighter middle, and partially resolved.[3] NGC 7421 is located at an estimated distance of 81.6 millionlight-years (25.01 Mpc) from the Sun.[2] It is a member of theIC 1459galaxy group.[5]
In theThird Reference Catalogue of Bright Galaxies, NGC 7421 was assigned amorphological classification of SB(rs)bc, which indicates abarred spiral galaxy (SB) with a transitional ring structure (rs) and moderately woundspiral arms (bc).[4] Thegalactic plane is inclined at an angle of 36.2° to theplane of the sky, with the major axis aligned along aposition angle of 80.6°. It displays an asymmetric morphology, which shows up in a lopsided optical appearance and in the distribution ofCO andneutral hydrogen atoms. New stars are forming at a rate of0.274±0.041 M☉·yr−1. The gas fraction and star formation rate is significantly lower than normal, suggesting an interaction with the external environment.[5]
The western boundary of this galaxy resembles abow shock that suggests an interaction with the intracluster medium. Radio mapping of neutral hydrogen by theATCA displays an extended wake to the north and south of the galaxy, supporting this hypothesis.[8] A pasttidal interaction may be needed to explain the asymmetry of this galaxy. A candidate galaxy isNGC 7418, which is located at anangular separation of~20′. However, there are notidal tails visible from such an encounter.[9] The total mass of the neutral hydrogen in this galaxy is1.5×109 M☉.[8]
Thetype II supernovaSN 2023abdg was observed in association with this galaxy. It was discovered on December 12, 2023, byATLAS.[10]
