New findings confirm existence of hot helium stars long-thought to be at the heart of hydrogen-poor supernovae and
Implications for Future Research
“If it turned out that these stars are rare, then our whole theoretical framework for all these different phenomena is wrong, with implications for supernovae, gravitational waves, and the light from distant galaxies,” Drout says. “This finding shows these stars really do exist.”
“Going forward, we are going to be able to do much more detailed physics with these stars,” Drout says. “For example, predictions for how many neutron star mergers we should see are dependent on the properties of these stars, such as how much material comes off of them in stellar winds. Now, for the first time, we’ll be able to measure that, whereas people have been extrapolating it before.”
Binary Stripped Stars and Cosmic Phenomena
Binary stripped stars have been previously evoked to explain why a third of core-collapse supernovae contain much less hydrogen than a typical explosion of a Red Supergiant star. Drout and her colleagues propose that these newly discovered stars will eventually explode as hydrogen-poor supernovae. These star systems are also thought to be necessary to form neutron star mergers, like those that emit
Stellar Partnerships and Evolution
“Many stars are part of a cosmic dance with a partner, orbiting each other in a binary system. They’re not solitary giants but part of dynamic duos, interacting and influencing each other throughout their lifetimes,” says Bethany Ludwig, a PhD student in in the David A. Dunlap Department of Astronomy & Astrophysics at the University Toronto and the third author on this paper. “Our work sheds light on these fascinating relationships, revealing a universe that is far more interconnected and active than we previously imagined.”
“Just as humans are social beings, stars too, especially the massive ones, are rarely alone,” Ludwig says.
As stars evolve and expand to become red giants, the hydrogen at the outer edges of one can be stripped by the gravitational pull of its companion—leaving a very hot helium core exposed. The process can take tens of thousands, or even hundreds of thousands, of years.
Challenges in Detecting Stripped Stars
Stripped stars are difficult to find because much of the light they emit is outside of the visible light spectrum and can be obstructed by dust in the universe or outshone by their companion stars.
Drout and her collaborators began their search in 2016. Having studied hydrogen-poor supernovae during her PhD, Drout set out to find the stripped stars thought to be at the heart of them during a DOI: 10.1126/science.ade4970
Collaborating institutions include the University of Toronto, the Observatories of the Carnegie Institution for Science, Max-Planck-Institut für Astrophysik, Anton Pannekoek Institute for Astronomy, Dunlap Institute for Astronomy & Astrophysics, and Steward Observatory.