Overview

A third of all massive stars are expected to lose their hydrogen-rich envelopes via binary interaction, revealing the hot and compact helium core. These "stripped stars" are thought to both be the progenitors for the majority of hydrogen-poor core-collapse supernovae (type IIb/Ib) and all binary neutron star mergers. Despite their importance, such intermediate-mass helium stars remained to be observed, questioning the fundamental theory behind binary stellar population models. I will show how, during my postdoc at Carnegie, we (1) developed a successful observational technique for identifying stripped stars, and (2) measured the stellar properties of a set of stripped stars in the Magellanic Clouds from intermediate resolution spectra taken with MagE. This first observed set of stripped stars opens the door for a variety of science to be done that previously was not possible, including, for example, constraining core spins of evolved massive stars and the ionizing contribution from binaries.