NGC 3938

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

NGC 3938 with SN 2005ay

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 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

See also

• List of NGC objects (3001–4000)