Messier 66 or M66, also known as NGC 3627, is an intermediate spiral galaxy in the southern, equatorial half of Leo. It was discovered by French astronomer Charles Messier[8] on 1 March 1780, who described it as "very long and very faint".[9] This galaxy is a member of a small group of galaxies that includes M65 and NGC 3628, known as the Leo Triplet or the M66 Group.[10] M65 and M66 are a common object for amateur astronomic observation, being separated by only 20′.[9]
M66 has a morphological classification of SABb,[5] indicating a spiral shape with a weak bar feature and loosely wound arms. The isophotal axis ratio is 0.32, indicating that it is being viewed at an angle.[5] M66 is receding from us with a heliocentric radial velocity of 696.3±12.7 km/s.[3] It lies 31[4] million light-years away and is about 95 thousand light-years across[11] with striking dust lanes and bright star clusters along sweeping spiral arms.
Gravitational interaction from its past encounter with neighboring NGC 3628 has resulted in an extremely high central mass concentration; a high molecular to atomic mass ratio; and a resolved non-rotating clump of H I material apparently removed from one of the spiral arms. The latter feature shows up visually as an extremely prominent and unusual spiral arm and dust lane structures as originally noted in the Atlas of Peculiar Galaxies.[12]
SN 1997bs (type uncertain, mag. 17) was discovered by the Lick Observatory Supernova Search (LOSS) on 15 April 1997.[16][17] This event was initially classified as a type IIn supernova, but more recent analysis suggests that it is instead either a luminous blue variable or a "gap" transient.[18][19]
SN 2009hd (type II, mag. 15.8) was discovered by Libert (Berto) Monard on 2 July 2009.[20][21]
^ abSkrutskie, Michael F.; Cutri, Roc M.; Stiening, Rae; Weinberg, Martin D.; Schneider, Stephen E.; Carpenter, John M.; Beichman, Charles A.; Capps, Richard W.; Chester, Thomas; Elias, Jonathan H.; Huchra, John P.; Liebert, James W.; Lonsdale, Carol J.; Monet, David G.; Price, Stephan; Seitzer, Patrick; Jarrett, Thomas H.; Kirkpatrick, J. Davy; Gizis, John E.; Howard, Elizabeth V.; Evans, Tracey E.; Fowler, John W.; Fullmer, Linda; Hurt, Robert L.; Light, Robert M.; Kopan, Eugene L.; Marsh, Kenneth A.; McCallon, Howard L.; Tam, Robert; Van Dyk, Schuyler D.; Wheelock, Sherry L. (1 February 2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708. ISSN0004-6256. S2CID18913331.
^ abde Vaucouleurs, G.; et al. (1991), Third reference catalogue of bright galaxies, 9, New York: Springer-Verlag.
^"SN1973R". Transient Name Server. IAU. Retrieved 3 December 2024.
^Evans, R. O.; McNaught, R. H. (1989). "Supernova 1989B in NGC 3627". International Astronomical Union Circular (4726): 1. Bibcode:1989IAUC.4726....1E.
^"SN1989B". Transient Name Server. IAU. Retrieved 3 December 2024.
^Treffers, R. R.; Peng, C. Y.; Filippenko, A. V.; Richmond, M. W.; Barth, A. J.; Gilbert, A. M. (1997). "Supernova 1997bs in NGC 3627". International Astronomical Union Circular (6627): 1. Bibcode:1997IAUC.6627....1T.
^"SN1997bs". Transient Name Server. IAU. Retrieved 3 December 2024.
^Van Dyk, Schuyler D.; Peng, Chien Y.; King, Jennifer Y.; Filippenko, Alexei V.; Richards, R. R.; Li, Weidong; Richmond, Michael W. (2000). "SN 1997bs in M66: Another Extragalactic η Carinae Analog?". Publications of the Astronomical Society of the Pacific. 112 (778): 1532–1541. arXiv:astro-ph/0009027. doi:10.1086/317727.
^Monard, L. A. G. (2009). "Supernova 2009hd in M66". Central Bureau Electronic Telegrams. 1867: 1. Bibcode:2009CBET.1867....1M.
^"SN2009hd". Transient Name Server. IAU. Retrieved 3 December 2024.
^Sutaria, Firoza; Ray, Alak (June 2016), "No X-ray detection of SN2016cok by Swift XRT", The Astronomer's Telegram, 9189: 1, Bibcode:2016ATel.9189....1S.
^"SN2016cok". Transient Name Server. IAU. Retrieved 2 December 2024.