Origin of a Thermonuclear Supernova Explosion Unveiled through Radio Signal
Scientists from Stockholm University have unveiled the source of a thermonuclear supernova explosion, shedding light on its origin and underlying processes. Through the detection of strong emission lines of helium and the unprecedented observation of radio waves, astronomers have determined that the white dwarf star responsible for the explosion had a companion rich in helium.
The groundbreaking discovery made by researchers at Stockholm University provides valuable insights into the nature and mechanisms behind Type Ia supernovae, which play a vital role in measuring the expansion of the universe. It also offers answers to the longstanding question regarding the explosion of white dwarf stars and the characteristics of their progenitors. In this case, the progenitor is identified as a helium star that had undergone significant material loss just before the white dwarf's explosion.
Type Ia supernovae are of great importance to astronomers as they serve as key indicators for gauging the universe's expansion. However, the cause of these explosions has long remained a mystery. While it is known that the explosion occurs when a compact white dwarf star accumulates an excessive amount of matter from a companion star, the precise process and characteristics of the progenitor have remained elusive. The recent identification of supernova SN 2020eyj as having a helium star companion that experienced substantial material loss prior to the white dwarf's explosion represents a significant breakthrough.
Erik Kool, a post-doctoral researcher at Stockholm University's Department of Astronomy and the lead author of the study, explains, "Upon observing the clear signs of significant interaction with material from the companion star, we endeavored to detect it through radio emissions. This radio detection marks the first-ever observation of a Type Ia supernova, a pursuit that astronomers have pursued for decades."
The discovery of supernova 2020eyj was made by the Zwicky Transient Facility camera located on Palomar mountain, with the Oskar Klein Centre at Stockholm University among the contributing members.
"The Nordic Optical telescope on La Palma played a crucial role in monitoring this supernova," says Professor Jesper Sollerman, a co-author of the paper from Stockholm University's Department of Astronomy.
He further adds, "Spectra obtained from the large Keck telescope on Hawai’i immediately revealed the presence of highly unusual helium-dominated material surrounding the exploded star."
Joel Johansson, from the Department of Physics, emphasizes, "This is undeniably an extraordinary Type Ia supernova, yet still connected to those we employ for measuring the universe's expansion."
He concludes, "While conventional Type Ia supernovae typically exhibit consistent luminosity upon explosion, this supernova demonstrates that there are numerous pathways to the explosion of a white dwarf star."
