Press Releases

DATE2021.12.09 #Press Releases

Researchers capture the fastest optical flash emitted from a newborn supernova


Overview of the press release

A team of astronomers have discovered the fastest optical flash of a Type Ia supernova, reports a study in the Astrophysical Journal Letters published on December 8.

Many stars end their lives through a spectacular explosion. Most massive stars will explode as a supernova. Though a white dwarf star is the remnant of an intermediate mass star like our Sun, it can explode if the star is part of a close binary star system, where two stars orbit around each other. This type of supernovae is classified as Type Ia supernovae.

Because of the uniform and extremely high brightness of the Type Ia supernova, which is about 5 billion times brighter than our Sun, they are widely used by researchers as a standard candle for distance measurements in astronomy. As the most successful example Type Ia supernovae helped researchers discover the accelerating expansion of our universe. But despite the great success of the Type Ia supernova cosmology, researchers are still puzzled by basic questions such as what the progenitor systems of Type Ia supernovae are, and how Type Ia supernova explosions are ignited.

To figure out these long-standing issues, a team of astronomers, led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Researcher Ji-an Jiang, and consisting of researchers from the University of Tokyo, Kyoto University, Hiroshima University and other institutions, attempted to catch Type Ia supernovae within one day of their explosions, called early-phase Type Ia supernovae, using new-generation wide-field survey facilities, including the Tomo-e Gozen camera on the Kiso Schmidt telescope operated by the University of Tokyo, the first wide-field mosaic CMOS sensor imager in the world.

By regularly checking early-phase supernova candidates discovered by the Tomo-e transient survey, one transient, Tomo-e202004aaelb, caught Jiang's attention.

"Tomo-e202004aaelb was discovered with high brightness on April 21 in 2020. Surprisingly, its brightness showed significant variation in the next two days and then behaved like a normal early-phase Type Ia supernova. We have discovered several early-phase Type Ia supernovae that show interesting excess emission in the first few days of their explosions but have never seen such a fast and prominent early emission in optical wavelengths. Thanks to the high-cadence survey mode and the excellent performance of Tomo-e Gozen, we can perfectly catch this amazing feature for the first time. Such a prompt early flash should originate from a different origin compared to previously dis covered early-excess Type Ia supernovae,” said Jiang.

Figure :  The astronomical art of the high energy released from an interaction between a confined CSM (torus-like) and supernova ejecta soon after the white dwarf explosion. (Credit: Kiso Observatory, The University of Tokyo)


Associate Professor Shigeyuki Sako (Department of Astronomy, Institute of Astronomy, The University of Tokyo), Professor Mamoru Doi (Department of Astronomy, Institute of Astronomy, The University of Tokyo), et al, contributed to this research.

To read the full press release, please visit the website of Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU).


Publication details


The Astrophysical Journal Letters

Title Discovery of the Fastest Early Optical Emission from Overluminous SN Ia 2020hvf: A Thermonuclear Explosion within a Dense Circumstellar Environment
Authors Ji-an Jiang, Keiichi Maeda, Miho Kawabata, Mamoru Doi, Toshikazu Shigeyama, Masaomi Tanaka, Nozomu Tominaga, Ken’ichi Nomoto, Yuu Niino, Shigeyuki Sako, Ryou Ohsawa, Malte Schramm, Masayuki Yamanaka, Naoto Kobayashi, Hidenori Takahashi, Tatsuya Nakaoka, Koji S. Kawabata, Keisuke Isogai, Tsutomu Aoki, Sohei Kondo, Yuki Mori, Ko Arimatsu, Toshihiro Kasuga, Shin-ichiro Okumura, Seitaro Urakawa, Daniel E. Reichart, Kenta Taguchi , Noriaki Arima, Jin Beniyama, Kohki Uno, and Taisei Hamada