Institute of Astronomy

Binaries of Red Giants and Main-sequence Dwarfs

SpeakerTalk DateTalk Series
Peter Eggleton29 July 2016Binary Stars Talks

Abstract

Many comparisons have been made of eclipsing double-main-sequence binaries, and the result is usually good agreement between observation and theory, though with some qualifications. But more evolved stars are harder to compare because the orbits are usually larger, eclipses rarer, and radial velocities amplitudes less. We compare 57 such observed binaries with theoretical models that include mass loss rotationally driven by the RS CVn mechanism, and rotation affected by tidal friction.  Provided a rather specific formulation of convective core overshooting is used, we usually get reasonable agreement; except that there appears to be something inherently chaotic about the mass loss proces so that some systems lose 10 or more times more, and others 10 or more times less, in rather similar binaries. We note 2 systems where, we believe, an initially triple system has undergone a merger in a sub-binary, leading to an anomalous wide binary. Two systems have a blue giant or supergiant; and  seven have two red giants.

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