In what year was the most recent confirmed supernova in the galaxy M84?

The most recent confirmed supernova in the galaxy M84 occurred in 1991, specifically designated as SN 1991bg. M84, located in the Virgo Cluster, is well-studied by astronomers, and the discovery of this supernova was notable as it provided significant insights into stellar evolution and the nature of supernovae.

Supernovae like SN 1991bg can vary in type, with this one classified as a Type Ia supernova. Type Ia supernovae occur in binary systems where one star is a white dwarf that accumulates matter from its companion star until it reaches a critical mass and undergoes a runaway nuclear reaction. The observations of SN 1991bg resulted in important contributions to cosmology, particularly in understanding the distances to galaxies and the expansion of the universe.

The mention of the years 1987, 1995, and 2000 relates to other supernova occurrences or observations in different galaxies. However, for M84 specifically, the 1991 supernova remains a key event in the study of celestial phenomena within that galaxy. Thus, the year 1991 is particularly significant in the context of supernova research and its implications.