Massive stars can lose their outer hydrogen layers through interactions with other stars in binary systems. These stripped stars are believed to play a crucial role in the formation of merging neutron stars and certain types of supernovae known as stripped-envelope supernovae. Recently, we made an important discovery by identifying a population of such stripped stars in a separate research paper.

In this current study, we've closely examined ten stripped stars by analyzing their spectra and fitting the models to precisely determine their characteristics. Our findings reveal that these stars closely match the expected properties predicted by theoretical models of binary star evolution. These properties include very high surface temperatures (50,000 to 100,000 degrees Kelvin), strong surface gravity, and a lack of hydrogen with an abundance of helium on their outer layers. Further, these compact stars span a wide range of luminosities.

What's particularly interesting is that these stars have weaker stellar winds compared to what was previously predicted using extrapolations from Wolf-Rayet stars. Using this data, we estimate that their current masses fall in the intermediate range, roughly between 1 to 8 times the mass of our Sun. This suggests that these stars likely originated from massive progenitor stars, which were originally between 5 to 25 times the mass of our Sun, and some of them may eventually undergo core collapse, leading to the formation of neutron stars or black holes.

These intermediate-mass helium-rich stars provide valuable reference points for understanding the evolution of binary star systems and predicting the populations of these intriguing celestial objects.

Read more here.