NGC 3938 explained

NGC 3938
Epoch:	J2000
Type:	SA(s)c^[1]
Ra:	^[2]
Dist Ly:	43 Mly
Appmag V:	10.9
Size V:	5.4 × 4.9
Constellation Name:	Ursa Major

NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered on 6 February 1788 by William Herschel. It is one of the brightest spiral galaxies in the Ursa Major South galaxy group and is roughly 67,000 light years in diameter.^[3] It is approximately 43 million light years away from Earth.^[2] NGC 3938 is classified as type Sc under the Hubble sequence, a loosely wound spiral galaxy with a smaller and dimmer bulge.^[4] The spiral arms of the galaxy contain many areas of ionized atomic hydrogen gas, more so towards the center.^[5]

Supernovae

Five supernovae have been identified within NGC 3938.

• SN 1961U (typeII, mag. 13.7) was discovered by Paul Wild on 28 December 1961.^{[6] [7]} [Note: some sources incorrectly list the discovery date as 2 January 1962.]
• SN 1964L (typeIc, mag. 13.3) was discovered by Paul Wild on 11 December 1964.^{[8] [9]}
• SN 2005ay (type II, mag. 15.6) was discovered by Doug Rich on 27 March 2005.^{[10] [11]}
• SN 2017ein (type Ic, mag. 17.6) was discovered by Ron Arbour on 25 May 2017 and peaked at magnitude 14.9.^{[12] [13]} Images taken before the explosion point to a progenitor mass between ~47-48, if it was in a single star system, and ~60-80, if it was in a binary star system.
• SN 2022xlp (typeIa, mag. 17) was discovered by Kōichi Itagaki on 13 October 2022.^[14]

Notes and References

1. Web site: Results for object NGC 3938 (NGC 3938). NASA/IPAC Extragalactic Database. California Institute of Technology. 2021-02-28.
2. Web site: Spiral Galaxy NGC 3839 . George Normandin . 5 May 2005 . kopernik.org . 30 December 2011.
3. Web site: The Ursa Major Groups . Atlas of the Universe . 30 December 2011.
4. van der Kruit . P.C. . Shostak . G.S. . Studies of Nearly Face-on Spiral Galaxies. Astronomy and Astrophysics. 105. 351–358. 1982. 1982A&A...105..351V . 25 June 2014 .
5. Jiménez-Vicente. J.. 4 . E. Battaner . M. Rozas . H. Castañeda . C. Porcel . Fabry-Perot observations of the ionized gas in NGC 3938. Astronomy and Astrophysics. 342. 417–425. 1999. 1999A&A...342..417J. astro-ph/9811391 .
6. Web site: Transient Name Server . SN1961U . . 27 November 2024.
7. Web site: Circular No. 1787 (sides 2 and 3) . Thernoe . K. A. . 4 January 1962 . Central Bureau for Astronomical Telegrams . Observatory Copenhagen . 27 November 2024.
8. Web site: Transient Name Server . SN1964L . . 27 November 2024.
9. Web site: Circular No. 1882 (side 1) . Thernoe . K. A. . 29 December 1964 . Central Bureau for Astronomical Telegrams . Observatory Copenhagen . 27 November 2024.
10. Web site: Supernova 2005ay in NGC 3938 . Rochester Astronomy . 29 January 2013.
11. Web site: Transient Name Server . SN2005ay . . 27 November 2024.
12. Web site: Transient Name Server . SN2017ein . . 27 November 2024.
13. Web site: Supernovae 2017ein in NGC 3938 . www.rochesterastronomy.org . 29 June 2017 . en.
14. Web site: Transient Name Server . SN2022xlp . . 27 November 2024.