Radio observations andHubble Space Telescope images of M84 have revealed two jets of matter shooting out from its center as well as a disk of rapidly rotating gas and stars indicating the presence of a 1.5×109M☉[9] supermassiveblack hole. It also has a few young stars andstar clusters, indicatingstar formation at a very low rate.[10] The number ofglobular clusters is1,775±150, which is much lower than expected for an elliptical galaxy.[11]
Viewed from Earth its half-light radius, relative angular size of its 50% peak of lit zone of the sky, is72.5″, thus just over anarcminute.
SN 1957B (TypeIa, mag. 12.5) was discovered by Howard S. Gates on 28 April 1957, and independently by Dr. Giuliano Romano on 18 May 1957.[12][13][14]
SN 1980I (Type Ia, mag. 14) was discovered by M. Rosker on 13 June 1980.[15][16] Historically, this supernova has been catalogued as belonging to M84, but it may have been in either neighboring galaxyNGC 4387 orM86.[17]
SN 1991bg (Type Ia-pec, mag. 14) was discovered byReiki Kushida on 3 December 1991.[18][19] This supernova has been studied extensively as a peculiar and underluminous Type Ia, and is now used as a template, with similar events being classified asType Ia-91bg-like.[20]
This high rate of supernovae is rare for elliptical galaxies, which may indicate there is a population of stars of intermediate age in M84.[11]
^Ford, Alyson; Bregman, J. N. (2012). "Detection of Ongoing, Low-Level Star Formation in Nearby Ellipticals".American Astronomical Society.219: 102.03.Bibcode:2012AAS...21910203F.
^Hansen, Julie M. Vinter (24 May 1957)."Circular No. 1600".Central Bureau for Astronomical Telegrams. Observatory Copenhagen. Retrieved30 November 2024.
^"SN1957B".Transient Name Server.IAU. Retrieved4 December 2024.
^Kristian, J.; Rosker, M.; Smith, H. (1980). "Possible Supernova in Virgo Cluster".International Astronomical Union Circular (3492): 1.Bibcode:1980IAUC.3492....1K.
^"SN1980I".Transient Name Server.IAU. Retrieved4 December 2024.
