NGC 3938
Galaxy in the constellation Ursa Major
From Wikipedia, the free encyclopedia
NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered by German-British astronomer William Herschel on 6 February 1788.[3] It is one of the brightest spiral galaxies in the Ursa Major South galaxy group and is roughly 76,000 light years in diameter.[2][4] It is approximately 41.4 million light years away from Earth.[1] NGC 3938 is classified as type Sc under the Hubble sequence, a loosely wound spiral galaxy with a smaller and dimmer bulge.[5] The spiral arms of the galaxy contain many areas of ionized atomic hydrogen gas, more so towards the center.[6]
| NGC 3938 | |
|---|---|
NGC 3938 imaged by Mount Lemmon SkyCenter of the University of Arizona | |
| Observation data (J2000 epoch) | |
| Constellation | Ursa Major[1] |
| Right ascension | 11h 52m 49.4319s[2][1] |
| Declination | +44° 07′ 14.840″[2] |
| Redshift | 0.002695[2] |
| Heliocentric radial velocity | 808±2 km/s[2] |
| Distance | 41.40 ± 9.00 Mly (12.694 ± 2.760 Mpc)[2] |
| Apparent magnitude (V) | 10.9[1] |
| Characteristics | |
| Type | SA(s)c[2] |
| Size | ~76,400 ly (23.42 kpc) (estimated)[2] |
| Apparent size (V) | 5.4′ × 4.9′[1] |
| Other designations | |
| IRAS 11502+4423, UGC 6856, MCG +07-25-001, PGC 37229, CGCG 214-034[2] | |
NGC 3938 is a member of the NGC 4111 Group,[7] which is part of the Ursa Major Cloud and is the second largest group in the cloud after the NGC 3992 Group.[8][9][10]
Supernovae and Luminous Red Nova
Five supernovae have been identified within NGC 3938:
- SN 1961U (Type II, mag. 13.7) was discovered by Paul Wild on 28 December 1961.[11][12] [Note: some sources incorrectly list the discovery date as 2 January 1962.]
- SN 1964L (Type Ic, mag. 13.3) was discovered by Paul Wild on 11 December 1964.[13][14]
- SN 2005ay (Type II, mag. 15.6) was discovered by Doug Rich on 27 March 2005.[15][16][17]
- SN 2017ein (Type Ic, mag. 17.6) was discovered by Ron Arbour on 25 May 2017 and peaked at magnitude 14.9.[18][19] Images taken before the explosion point to a progenitor mass between ~47-48M☉, if it was in a single star system, and ~60-80M☉, if it was in a binary star system.[20]
- SN 2022xlp (Type Ia, mag. 17) was discovered by Kōichi Itagaki on 13 October 2022.[21]
One luminous red nova has been observed in NGC 3938:
- AT 2022ckk (type LRN, mag. 19.6766) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 13 February 2022.[22]
Gallery
Artist's impression of progenitor star to a type Ic supernova SN 2017ein in NGC 3938.[23]
Spiral galaxy NGC 3938, by HST. Location of SN 2005ay remnant is marked.
The location of SN 2017ein, by HST.
NGC 3938 by the Sloan Digital Sky Survey
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