<p>Astronomers at the University of Toronto have discovered a population of massive stars that have been stripped of their hydrogen envelopes by their companions in binary systems. The findings, <a href="https://www.science.org/doi/10.1126/science.ade4970">published today in <em>Science</em></a><em>, </em>shed light on the hot helium stars that are believed to be the origins of hydrogen-poor core-collapse supernovae and neutron star mergers.</p>