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First Stars III
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Poster
Title:>Radii of accreting Main Sequence stars at various metallicities Author(s): Selma de Mink, Michiel Cottaar and Onno Pols Abstract:In close binaries mass can be transferred from one star to the other. In case of rapid mass transfer the accreting star cannot maintain thermal equilibrium and swells up, potentially so much that a contact binary is formed. We investigated how main sequence stars react to mass accretion as function of their metallicity, $Z$, using the STARS evolution code (originally developed by Eggleton 1971). We find that the maximum radius during accretion increases with metallicity, for $Z > 10^{-3}$, which can be understood as a result of the increase of opacity with metallicity. As a consequence many binaries at low metallicity will avoid contact during rapid mass transfer phases. This can have large implications for binary formation channels for objects like Supernovae, GRB's, double neutron star systems and X-ray binaries. The study of binary evolution as function of metallicity deserves attention.
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