The discovery of Type Ia supernovae with hydrogen, a rarity, could help astronomers trace the origins of the explosive cosmic phenomena.
Type Ia supernovae occur when the white dwarf in a binary stellar system dies a fiery, explosive death. Usually, Type Ia supernovae are without hydrogen. But this particular explosion boasted plenty of hydrogen.
Scientists aren’t sure how Type Ia supernovae form, but one popular theory is that the white dwarf begins stealing stellar material from its companion, slowly expanding until it’s engorged and explodes.
Some astronomers, however, suggest Type Ia supernovae are produced by the collision of two white dwarfs. To test their theory, researchers conducted a survey of Type Ia supernovae and their chemical signatures.
Over the last few years, scientists have identified a handful of hydrogen-rich Type Ia supernovae. But, ASASSN-18tb, the hydrogen-positive supernova detailed in the latest study — already a rare find — is unique in several ways.
“It’s possible that the hydrogen we see when studying ASASSN-18tb is like these previous supernovae, but there are some striking differences that aren’t so easy to explain,” Juna Kollmeier, astronomer at the Carnegie Institution for Science, said in a news release.
The previous hydrogen-rich Type Ia supernovae were found in young, star-forming galaxies. Hydrogen is plentiful in active stellar factories. ASASSN-18tb was discovered inside an old galaxy, surrounded by old stars. The Type Ia supernova also features less hydrogen than the others.
“One exciting possibility is that we are seeing material being stripped from the exploding white dwarf’s companion star as the supernova collides with it,” researcher Anthony Piro said. “If this is the case, it would be the first-ever observation of such an occurrence.”
The rare find, detailed in the journal Monthly Notices of the Royal Astronomical Society, could help scientists finally confirm the origins of Type Ia supernovae.,