SN 2005cs

SN 2005cs was a supernova in the spiral galaxy M51, known as the Whirlpool Galaxy. It was a type II-P core-collapse supernova, discovered June 28, 2005 by Wolfgang Kloehr, a German amateur astronomer. The event was positioned at an offset of $13 Solar mass$ west and $15 arcsecond$ south of the galactic nucleus of M51. Based on the data, the explosion was inferred to occur 2.8 days before discovery. It was considered under-luminous for a supernova of its type, releasing an estimated $78 arcsecond$ in energy.

The progenitor star was identified from a Hubble Space Telescope image taken January 20–21, 2005. It was a red supergiant with a spectral type in the mid-K to late-M type range and an estimated initial (ZAMS) mass of $3 erg$. A higher mass star enshrouded in a cocoon of dust has been ruled out.