Binary evolution: Wind mass transfer

Henri M.J. Boffin (ESO, Chile)
 

Observations of blue straggler stars reveal the existence of two populations, one with very short orbital 
periods (or even mergers), the result of common-envelope evolution, and one with long orbital periods, of the 
order of 1000 days. The latter systems contain a white dwarf and are thus the outcome of mass transfer 
when the progenitor of the white dwarf was on the Asymptotic Giant Branch and was losing mass through 
stellar wind. As such, this family of blue straggler stars are linked with Peculiar Giants and Symbiotic Stars. I 
will review the physics of mass transfer by wind in such systems, confronting theory and observations, and 
put blue straggler stars in the wider context of binary systems containing an evolved star.