A newly discovered nearby supernova whose star ejected up to a full solar mass of material in the year prior to its explosion is challenging the standard theory of stellar evolution. The new observations are giving astronomers insight into what happens in the final year prior to a star’s death and explosion.
SN 2023ixf is a new Type II supernova discovered in May 2023 by amateur astronomer Itagaki of Yamagata, Japan shortly after its progenitor, or origin star, exploded. Located about 20 million light-years away in the Pinwheel Galaxy, SN 2023ixf’s proximity to Earth, the supernova’s extreme brightness, and its young age make it a treasure trove of observable data for scientists studying the death of massive stars in supernova explosions.
Type II or core-collapse supernovae occur when red supergiant stars at least eight times, and up to about 25 times the mass of the Sun, collapse under their own weight and explode. While SN 2023ixf fit the Type II description, follow-up multi-wavelength observations led by astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA), and using a wide range of CfA’s telescopes, have revealed new and unexpected behavior.
Within hours of going supernova, core-collapse supernovae produce a flash of light that occurs when the shock wave from the explosion reaches the outer edge of the star. SN 2023ixf, however, produced a light curve that didn’t seem to fit this expected behavior. To better understand SN 2023ixf’s shock breakout, a team of scientists led by CfA postdoctoral fellow Daichi Hiramatsu analyzed data from the 1.5m Tillinghast Telescope, 1.2m telescope, and MMT at the Fred Lawrence Whipple Observatory, a CfA facility located in Arizona, as well as data from the Global Supernova Project — a key project of the Las Cumbres Observatory, NASA’s Neil Gehrels Swift Observatory, and many others. This multi-wavelength study, which was published this week in The Astrophysical Journal Letters, revealed that, in…