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.[1] 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 ~47-48M☉, if it was in a single star system, and ~60-80M☉, if it was in a binary star system.[14]
^"SN1961U". Transient Name Server. IAU. Retrieved 27 November 2024.
^Thernoe, K. A. (4 January 1962). "Circular No. 1787 (sides 2 and 3)". Central Bureau for Astronomical Telegrams. Observatory Copenhagen. Retrieved 27 November 2024.
^"SN1964L". Transient Name Server. IAU. Retrieved 27 November 2024.
^Thernoe, K. A. (29 December 1964). "Circular No. 1882 (side 1)". Central Bureau for Astronomical Telegrams. Observatory Copenhagen. Retrieved 27 November 2024.