Type Ia supernovae occur when a white dwarf, the ‘corpse’ of a Sun-like star, 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 their 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 parent system was unknown. Now, the first radio observation of a type Ia supernova confirms that it comes from a double star system composed of a white dwarf and a solar-type star. O results They 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 was tried without result for decades”, explains Erik Kool, researcher of the University of Stockholm and lead author of the article.
This first radio detection of a type Ia supernova is a milestone that allowed us to demonstrate that the white dwarf that exploded was accompanied by a normal non-degenerate star before the explosion.
Javier Moldón, researcher at IAA-CSIC
Type Ia supernovae always contain a white dwarf, which receives material from its companion. However, it was not known whether this 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 allowed us to demonstrate that the white dwarf that exploded was accompanied by a normal, non-degenerate star before the explosion,” says Javier Moldón, researcher at the Institute of Astrophysics of Andalusia ( IAA-CSIC) participating in discovery.
“In addition”, he adds, “with these observations we can estimate the mass and geometry of the material that surrounds the supernova, which allows us to better understand what the system was like before the explosion”.
a single supernova
This work, whose contribution in radio data was led by the IAA-CSIC, confirmed that the material ejected in the supernova explosion collided, after traveling sixty days, with the material that involved the system, composed mainly of helium , indicating that the star companion was not a white dwarf.
Furthermore, the models predicted that the radio emission, if it existed, would take many months to detect, and indeed, the scientific team had to wait a year and a half to detect the supernova’s radio counterpart.
The scientific team had to wait a year and a half to detect the supernova’s radio counterpart.
“The unusual light curve of SN 2020eyj, the infrared emission, the detection of helium emission lines and the unprecedented radio detection make this supernova unique, a treasure trove of information with implications in several fields of research”, says Miguel Pérez Towers. , 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 this type of supernova, a way 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.
The result was possible thanks to the e-MERLIN, a set of radio telescopes with very high angular resolution, and the data analysis was carried out from the Spanish prototype of the SKA Regional Center (SPSRC) of the IAA-CSIC, which has the support of the Severo project Ochoa of the IAA and which facilitates the processing of data from observatories that preceded the SKAO, such as e-MERLIN.
EC Kool et al. A type Ia supernova detected by radio with helium-rich circumstellar material. Nature2023