Recently discovered evidence of extreme pre-explosion mass loss in supernovae indicates that more may be going on in the final years of a star’s life than previously thought.
A newly discovered nearby supernova, whose star ejected up to an entire solar mass of material in the year before it exploded, challenges the standard theory of stellar evolution. New observations are giving astronomers insight into what happens in a star’s final year before it dies and explodes.
Nuclear collapse supernova and SN 2023ixf
SN 2023ixf is a new type II supernova discovered in May 2023 by amateur astronomer Koichi Itagaki from Yamagata, Japan, shortly after its ancestor, or origin star, exploded. Located about 20 million light-years away in the Pinwheel Galaxy, SN 2023ixf is close to Earth, and its supernovae are extremely bright and young, providing observable data for scientists studying the death of massive stars due to supernova explosions. It has become a treasure trove.
A type II supernova, or nuclear collapse supernova, occurs when a red supergiant star collapses under its own weight and explodes with a mass at least eight times the mass of the Sun, and up to about 25 times the mass of the Sun. SN 2023ixf fits the Type II description, but astronomers at the Center for Astrophysics are conducting follow-up multiwavelength observations. Harvard University and Smithsonian University (CFA), the use of CfA’s wide range of telescopes revealed new and unexpected behavior.
Within hours of a supernova explosion, a nuclear collapse supernova produces a flash of light that occurs when the shock wave from the explosion reaches the star’s outer edge. However, SN 2023ixf produced a light curve that does not seem to fit this expected behavior. To better understand SN 2023ixf’s shock breakout, a team of scientists led by CfA postdoctoral researcher Daichi Hiramatsu analyzed data from the 1.5-meter Tillinghast telescope, the 1.2-meter telescope, and his MMT. Fred Lawrence Whipple Observatorydata from the Global Supernova Project, a major project of the CfA facility in Arizona, and Las Cumbres Observatory; NASANeil Gehrels Swift Observatory, and many others. This multi-wavelength research will begin this week. of Astrophysics Journal Letterrevealed that SN 2023ixf’s shocking breakout was delayed by several days, largely contrary to expectations and theories of stellar evolution.
What Delayed Shock Breakout Means
“The delayed onset of the shock wave is direct evidence of the presence of dense matter due to recent mass loss,” Hiramatsu said, noting that such extreme mass loss is unusual for Type II supernovae. he added. “Our new observations reveal a significant and unexpected amount of mass loss, close to the mass of the Sun, in the last year before the explosion.”
SN 2023ixf challenges astronomers’ understanding of the evolution of massive stars and how they become supernovae. Scientists know that nuclear collapse supernovae are the primary origin point for the formation and evolution of atoms, neutron stars, and black holes in the universe, but little is known about the years leading up to a star’s explosion. yeah. New observations point to potential instability in the final years of a star’s life that could result in extreme mass loss. This may be related to the final stages of nuclear combustion of high-mass elements such as silicon in the star’s core.
Further observations and collaborative research
In parallel with Hiramatsu’s multi-wavelength observations, Ed Berger, professor of astronomy at Harvard University and Hiramatsu’s advisor, and CfA conducted millimeter-wave observations of supernovae using CfA’s observation equipment. submillimeter array (SMA) The summit of Mauna Kea in Hawaii. These data are Astrophysics Journal Letterdirectly traced the collision between supernova debris and dense material that was lost before the explosion. “SN 2023ixf exploded at exactly the right time,” Berger said. “Just a few days ago, we launched a new ambitious three-year program to study supernova explosions using the SMA, and this exciting nearby supernova is our first target. did.”
“The only way to understand how a massive star behaves in the last few years of its life before exploding is to discover a supernova when it is very young, preferably nearby, and combine it with multiple “It’s about studying across wavelengths,” Berger said. “Using both optical and millimeter-wave telescopes, we effectively turned SN 2023ixf into a time machine, recreating what its progenitor star was doing up until the moment of its death.”
The significance of being an amateur astronomer
The supernova discovery itself and its immediate follow-up has important implications for astronomers around the world, including those doing science in their own backyards. Mr. Itagaki discovered this supernova on May 19, 2023 from a private astronomical observatory in Okayama, Japan. Combining data from Itagaki and other amateur astronomers determined the time of the explosion. Accuracy This will give professional astronomers at CfA and other observatories a head start on their investigations. CfA astronomers have continued to collaborate with Itagaki on ongoing optical observations.
“Partnerships between amateur and professional astronomers have a long tradition of success in the supernova field,” Hiramatsu said. “In the case of SN 2023ixf, as soon as we discovered SN 2023ixf, we received an urgent email from Koichi Itagaki. Without this relationship and Mr. Itagaki’s research and dedication, we would not be able to avoid the evolution of massive stars and their supernova explosions. I would have missed the opportunity to gain a critical understanding of.”
References:
“From Discovery to the First Month of Type II Supernova 2023IXF: Massive and Variable Mass Loss in the Final Year Before the Explosion” Daichi Hiramatsu, Daichi Tsuna, Ed Berger, Koichi Itagaki, Jared A. Goldberg, Sebastian Gomez, Kisharay De, Griffin Hosseinzadeh, K. Azali Bostroem, Peter J. Brown, Iea Alkavy, Alison Vierilla, Peter K. Blanchard, Gilbert A. Eskeld, Joseph Farrar, D. Andrew. Howell, Tatsuya Matsumoto, Curtis McCurry, Megan Newsome, Estefania Padilla Gonzalez, Craig Pellegrino, Jaehyon Rhee, Giacomo Terreran, József Vinkó, J. Craig Wheeler, September 19, 2023. Astrophysics Journal Letter.
DOI: 10.3847/2041-8213/acf299
“Millimeter-wave observations of Type II SN 2023ixf: Constraints on the near-stellar medium” Ed Berger, Garrett K. Keating, Raffaella Malgutti, Keiichi Maeda, Kate D. Alexander, Yvette Sendes, Taraneh Eftekari, Mark・Gurwel, Daichi Hiramatsu, Anna YQ Ho, Tanmoy Laskar, Ramprasad Rao, Peter KG Williams, July 10, 2023, Astrophysics Journal Letter.
DOI: 10.3847/2041-8213/ace0c4