%0 Generic %1 drout2023discovery %A Drout, M. R. %A Götberg, Y. %A Ludwig, B. A. %A Groh, J. H. %A de Mink, S. E. %A O'Grady, A. J. G. %A Smith, N. %D 2023 %K astronomy binary_systems helium %T Discovery of the missing intermediate-mass helium stars stripped in binaries %U https://arxiv.org/abs/2307.00061 %X The theory of binary evolution predicts that many massive stars should lose their hydrogen-rich envelopes via interaction with a companion -- revealing hot helium stars with masses of ∼2--8M⊙. However, only one candidate system had been identified, leaving a large discrepancy between theory and observation. Here, we present a new sample of stars -- identified via excess ultraviolet emission -- whose luminosities, colors, and spectral morphologies are consistent with predictions for the missing population. We detect radial velocity variations indicative of binary motion and measure high temperatures (Teff∼60−100kK), high surface gravities (log(g)∼5) and depleted surface hydrogen mass fractions (XH,surf≲0.3), which match expectations for stars with initial masses between 8--25 M⊙ that have been stripped via binary interaction. These systems fill the helium star mass gap between subdwarfs and Wolf-Rayet stars, and are thought to be of large astrophysical significance as ionizing sources, progenitors of stripped-envelope supernovae and merging double neutron stars.

@misc{drout2023discovery, abstract = {The theory of binary evolution predicts that many massive stars should lose their hydrogen-rich envelopes via interaction with a companion -- revealing hot helium stars with masses of ∼2--8M⊙. However, only one candidate system had been identified, leaving a large discrepancy between theory and observation. Here, we present a new sample of stars -- identified via excess ultraviolet emission -- whose luminosities, colors, and spectral morphologies are consistent with predictions for the missing population. We detect radial velocity variations indicative of binary motion and measure high temperatures (Teff∼60−100kK), high surface gravities (log(g)∼5) and depleted surface hydrogen mass fractions (XH,surf≲0.3), which match expectations for stars with initial masses between 8--25 M⊙ that have been stripped via binary interaction. These systems fill the helium star mass gap between subdwarfs and Wolf-Rayet stars, and are thought to be of large astrophysical significance as ionizing sources, progenitors of stripped-envelope supernovae and merging double neutron stars. }, added-at = {2023-12-17T01:13:07.000+0100}, archiveprefix = {arXiv}, author = {Drout, M. R. and Götberg, Y. and Ludwig, B. A. and Groh, J. H. and de Mink, S. E. and O'Grady, A. J. G. and Smith, N.}, biburl = {https://www.bibsonomy.org/bibtex/2f44766ab97e76ee31e465f53a71d4dbf/tabularii}, eprint = {2307.00061}, interhash = {dc1add79b27642a46008feff3862e440}, intrahash = {f44766ab97e76ee31e465f53a71d4dbf}, keywords = {astronomy binary_systems helium}, primaryclass = {astro-ph.SR}, timestamp = {2023-12-17T01:13:07.000+0100}, title = {Discovery of the missing intermediate-mass helium stars stripped in binaries}, url = {https://arxiv.org/abs/2307.00061}, year = 2023 }