Extreme isolation of WN3/O3 stars and implications for their evolutionary origin as the elusive stripped binaries
AffiliationUniv Arizona, Steward Observ
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PublisherOXFORD UNIV PRESS
CitationNathan Smith, Ylva Götberg, Selma E de Mink; Extreme isolation of WN3/O3 stars and implications for their evolutionary origin as the elusive stripped binaries, Monthly Notices of the Royal Astronomical Society, Volume 475, Issue 1, 21 March 2018, Pages 772–782, https://doi.org/10.1093/mnras/stx3181
Rights© 2017 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
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AbstractRecent surveys of the Magellanic Clouds have revealed a subtype of Wolf-Rayet (WR) star with peculiar properties. WN3/O3 spectra exhibit both WR-like emission and O3 V-like absorption - but at lower luminosity than O3 V or WN stars. We examine the projected spatial distribution of WN3/O3 stars in the Large Magellanic Cloud as compared to O-type stars. Surprisingly, WN3/O3 stars are among the most isolated of all classes of massive stars; they have a distribution similar to red supergiants dominated by initial masses of 10(-15) M, and are far more dispersed than classical WR stars or luminous blue variables. Their lack of association with clusters of O-type stars suggests strongly that WN3/O3 stars are not the descendants of single massive stars (30 M circle dot or above). Instead, they are likely products of interacting binaries at lower initial mass (10-18 M circle dot). Comparison with binary models suggests a probable origin with primaries in this mass range that were stripped of their H envelopes through non-conservative mass transfer by a low-mass secondary. We show that model spectra and positions on the Hertzsprung-Russell diagram for binary-stripped stars are consistent with WN3/O3 stars. Monitoring radial velocities with high-resolution spectra can test for low-mass companions or runaway velocities. With lower initial mass and environments that avoid very massive stars, the WN3/O3 stars fit expectations for progenitors of Type Ib and possibly Type Ibn supernovae.
VersionFinal published version
SponsorsNSF [AST-1312221, AST-1515559]; Research Corporation for Science Advancement; National Aeronautics and Space Administration (NASA) through HST from the Space Telescope Science Institute [AR-14316]; NASA [NAS5-26555]; European Union's Horizon research and innovation programme ; Marie Sklodowska-Curie ; National Science Foundation [NSF PHY11-25915]