Extreme weight loss: Star sheds unexpected amounts of mass just before going supernova

A newly found close by supernova whose star ejected as much as a full solar mass of fabric within the 12 months previous to its explosion is difficult the usual idea of stellar evolution. The brand new observations are giving astronomers perception into what occurs within the closing 12 months previous to a star’s demise and explosion.

SN 2023ixf is a brand new Sort II supernova found in Could 2023 by newbie astronomer Kōichi Itagaki of Yamagata, Japan shortly after its progenitor, or origin star, exploded. Situated about 20 million light-years away within the Pinwheel Galaxy, SN 2023ixf’s proximity to Earth, the supernova’s excessive brightness, and its younger age make it a treasure trove of observable information for scientists finding out the demise of large stars in supernova explosions.

Sort II or core-collapse supernovae happen when pink supergiant stars at the least eight instances, and as much as about 25 instances the mass of the sun, collapse beneath their very own weight and explode. Whereas SN 2023ixf match the Sort II description, followup multi-wavelength observations led by astronomers on the Heart for Astrophysics | Harvard & Smithsonian (CfA), and utilizing a variety of CfA’s telescopes, have revealed new and sudden habits.

Inside hours of going supernova, core-collapse supernovae produce a flash of sunshine that happens when the shock wave from the explosion reaches the outer fringe of the star. SN 2023ixf, nonetheless, produced a light-weight curve that did not appear to suit this anticipated habits.

To higher perceive SN 2023ixf’s shock breakout, a crew of scientists led by CfA postdoctoral fellow Daichi Hiramatsu analyzed information from the 1.5m Tillinghast Telescope, 1.2m telescope, and MMT on the Fred Lawrence Whipple Observatory, a CfA facility situated in Arizona, in addition to information from the World Supernova Venture— a key challenge of the Las Cumbres Observatory, NASA’s Neil Gehrels Swift Observatory, and plenty of others.

This multi-wavelength examine, which was revealed this week in The Astrophysical Journal Letters, revealed that, in sharp contradiction to expectations and stellar evolution idea, SN 2023ixf’s shock breakout was delayed by a number of days.

“The delayed shock breakout is direct proof for the presence of dense materials from current mass loss,” mentioned Hiramatsu, including that such excessive mass loss is atypical of Sort II supernovae. “Our new observations revealed a big and sudden quantity of mass loss—near the mass of the sun—within the closing 12 months previous to explosion.”

SN 2023ixf challenges astronomers’ understanding of the evolution of large stars and the supernovae they grow to be. Though scientists know that core-collapse supernovae are main origin factors for the cosmic formation and evolution of atoms, neutron stars, and black holes, little or no is thought in regards to the years main as much as stellar explosions.

The brand new observations level to potential instability within the closing years of a star’s life, leading to excessive mass loss. This might be associated to the ultimate levels of nuclear burn-off of high-mass components, like silicon, within the star’s core.

In conjunction with multi-wavelength observations led by Hiramatsu, Edo Berger, professor of astronomy at Harvard and CfA, and Hiramatsu’s advisor, carried out millimeter-wave observations of the supernova utilizing CfA’s Submillimeter Array (SMA) on the summit of Maunakea, Hawai’i.

These information, that are additionally revealed in The Astrophysical Journal Letters, immediately tracked the collision between the supernova particles and the dense materials misplaced earlier than the explosion. “SN 2023ixf exploded precisely on the proper time,” mentioned Berger. “Just a few days earlier we commenced a brand new bold three-year program to review supernova explosions with the SMA, and this close by thrilling supernova was our first goal.”

“The one method to perceive how large stars behave within the closing years of their lives as much as the purpose of explosion is to find supernovae when they’re very younger, and ideally close by, after which to review them throughout a number of wavelengths,” mentioned Berger. “Utilizing each optical and millimeter telescopes we successfully turned SN 2023ixf right into a time machine to reconstruct what its progenitor star was doing up to date of its demise.”

The supernova discovery itself, and the instant followup, have vital that means to astronomers all over the world, together with these doing science in their very own backyards. Itagaki found the supernova on Could 19, 2023, from his non-public observatory in Okayama, Japan. Mixed information from Itagaki and different amateur astronomers decided the time of the explosion to an accuracy of inside two hours, giving skilled astronomers at CfA and different observatories a head begin of their investigations. CfA astronomers have continued to collaborate with Itagaki on on-going optical observations.

“The partnership between newbie {and professional} astronomers has a long-standing custom of success within the supernova discipline,” mentioned Hiramatsu. “Within the case of SN 2023ixf, I acquired an pressing e mail from Kōichi Itagaki as quickly as he found SN 2023ixf. With out this relationship, and Itagaki’s work and dedication, we’d have missed the chance to realize essential understanding of the evolution of large stars and their supernova explosions.”