The first radio detection of a type Ia supernova sheds light on the origin of these explosions

Type Ia supernovae occur when a white dwarf, the ‘corpse’ of a star similar to the Sun, absorbs material from a companion star and reaches a critical mass, equivalent to 1.4 solar masses, triggering an explosion whose luminosity will be, given its origin. , similar in almost all cases. This uniformity made type Ia supernovae ideal objects for measuring distances in the universe, but the origin and nature of the main system was unknown. Now, the first radio observation of a type Ia supernova confirms that it comes from a double star system made up of a white dwarf and a solar-type star. The results are published in the journal ‘Nature’. “When we saw, in the supernova SN2020eyj, signs of a strong interaction with the material of the companion star, we tried to observe the explosion in radio, something that had been tried without result for decades,” explains Erik Kool, a researcher at Stockholm University. . and main author of the article.

Type Ia supernovae always contain a white dwarf, which receives material from its companion. However, it was not known whether that companion was a white dwarf or a Sun-like star, something that could be revealed by radio imaging. “This first radio detection of a type Ia supernova is a milestone that has allowed us to demonstrate that the white dwarf that exploded was accompanied by a normal, non-degenerate star, before the explosion”, says Javier Moldón, IAA researcher – CSIC participating in the discovery. “In addition, with these observations we can estimate the mass and geometry of the material surrounding the supernova, which allows us to better understand what the system was like before the explosion.”

A unique supernova This work, whose contribution in radio data was led by the IAA-CSIC, has made it possible to confirm that the material ejected in the supernova explosion collided, after traveling for sixty days, with the material that surrounded the system, composed mainly of helium , indicating that the companion star was not a white dwarf.

Furthermore, the models predicted that the radio emission, if it existed, would take many months to become detectable, and in fact, the science team had to wait a year and a half to detect the supernova’s radio counterpart. “SN 2020eyj’s unusual light curve, unprecedented infrared emission, helium emission line detection, and radio detection make this supernova unique, a treasure trove of information with implications for multiple fields of research,” he says. Miguel Perez Torres. , IAA-CSIC researcher participating in the work– Studying more similar systems will allow us to better understand the origin of these standard candles and the chemical evolution of galaxies”. “Now that we have shown that radio observations can provide direct and unique information to understand these types of supernovae, a path is open to study these systems with the new generation of radio instruments, such as the Square Kilometer Array Observatory (SKAO) in the future”, concludes Moldón.