Researchers seize the quickest optical flash emitted from a new child supernova

A staff of astronomers has found the quickest optical flash of a Type Ia supernova, and reviews a examine in Astrophysical Journal Letters printed on December 8.

Many stars finish their lives by way of 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 might explode if the star is a part of a detailed binary star system, the place two stars orbit round one another. This kind of supernovae is classed as Type Ia supernovae.

Because of the uniform and very excessive brightness of the Type Ia supernova, which is about 5 billion occasions brighter than our sun, they’re broadly utilized by researchers as a normal candle for distance measurements in astronomy. As essentially the most profitable instance Type Ia supernovae helped researchers uncover the accelerating growth of our universe. But regardless of the good success of the Type Ia supernova cosmology, researchers are nonetheless puzzled by basic questions resembling what the progenitor programs of Type Ia supernovae are, and the way Type Ia supernova explosions are ignited.

To work out these long-standing points, a staff of astronomers, led by Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) Project Researcher Ji-an Jiang, tried to catch Type Ia supernovae inside one day of their explosions, known as early-phase Type Ia supernovae, utilizing new-generation wide-field survey services, together with the Tomo-e Gozen digital camera, the primary wide-field mosaic CMOS sensor imager on the planet.

By often checking early-phase supernova candidates found by the Tomo-e transient survey, one transient, Tomo-e202004aaelb, caught Jiang’s consideration.

“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,” stated Jiang.

Computational simulations by Kyoto University Associate Professor Keiichi Maeda confirmed that the origin of the mysterious quick optical flash may be defined by the vitality launched from an interplay between supernova ejecta and a dense and confined circumstellar materials (CSM) quickly after the supernova explosion.

“We have not seen such a short and bright flash from Type Ia supernovae before, even with a recently increasing number of very early discoveries soon after the supernova explosion in the last few years, including those discovered by our team. The nature of the CSM must reflect the nature of the progenitor star, and thus this is a key to understanding what kind of a star explodes and how they do so. A question is what makes this supernova so special,” stated Maeda.

Through spectroscopic observations by the Seimei telescope of Kyoto University, the staff discovered that the SN is a variant of brightest Type Ia supernovae.

“At the first look of the spectrum taken just after the initial flash, it stood out as something different from normal supernovae. We noticed that a brightest class of Type Ia supernovae might look like this one if they would be observed in such an early phase. Our classification was subsequently confirmed as the spectra evolve to look more and more similar to the previously found bright Type Ia supernovae,” stated Kyoto University Project Researcher Miho Kawabata.

The staff’s end result exhibits at the least a fraction of Type Ia supernovae originate from a dense CSM surroundings, which offers a stringent constraint on the progenitor system of those spectacular phenomena in our universe. Given that Tomo-e202004aaelb (SN 2020hvf) is way brighter than typical Type Ia supernovae used as the gap indicator, the invention will allow Jiang and his collaborators to check numerous theories which have been proposed for these peculiar overluminous Type Ia supernovae.

“Previously, we have constructed theoretical models of super-Chandrasekhar-mass rotating white dwarfs and their explosions. Such massive models can be consistent with the peak brightness of SN 2020hvf, but more theoretical work is necessary to explain the detailed observational properties. SN 2020hvf has provided a wonderful opportunity of collaboration between the theory and observations.” stated Kavli IPMU Senior Scientist Ken’ichi Nomoto.

Jiang’s staff will proceed on the lookout for the reply of the long-standing origin concern of Type Ia supernovae by finishing up transient surveys with telescopes everywhere in the world.

“We have used Type Ia supernovae to measure the expansion of the universe, although their origins are not well understood. The early-phase photometry of Type Ia supernovae provides unique information to understand their origins, and hence, should contribute to more accurate measurements of the expansion of the universe in near future,” stated Kavli IPMU Senior Scientist and University of Tokyo Professor Mamoru Doi.