6TH CONFERENCE ON HOT SUBDWARF
STARS AND RELATED OBJECTS

Tucson, Arizona, USA
May 19–24, 2013

These are the proceedings of the Sixth International Meeting on Hot Subdwarf Stars and Related Objects held at the University of Arizona, Tucson, in May 2013. The aim of these biennal workshops is to disseminate recent results on the properties, formation, and evolution of hot subdwarf stars and related objects, and to assess the impact of recent results on other areas of astrophysics.

Most hot subdwarfs belong to the B (sdB) type, and are evolved, low-mass, core He-burning stars that populate the Extreme Horizontal Branch (EHB). They have outer H-rich layers so thin that they evolve directly to the white dwarf domain aer core He exhaustion. The less numerous, hotter O (sdO) type subdwarfs make a less homogeneous family than their B counterparts. Some of them descend directly from sdB's on their way to the white dwarf stage, but others descend from the post-asymptotic branch evolutionary phase, while still others are very low mass post-red giant branch stars. Both the sdB and sdO types are found in the field and in some globular clusters.

These proceedings constitute a snapshot of the current research in the field. Topics include the formation of EHB stars, a key question in stellar evolution. Hot subdwarf stars are also an excellent tool for studying stellar evolution in close binary star systems with various companions. Many hot subdwarfs exhibit stellar pulsations, which allows asteroseismology to be used for inferring their fundamental parameters. Hot subdwarf stars and their atmospheres are also a laboratory for studying the effects of diffusion, weak stellar winds, radiative levitation, and gravitational settling.