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First Announcement
Hot Subdwarf Stars and Related Objects
6 - 10 June 2005, La Palma, Canary Islands, Spain
http://www.ing.iac.es/conferences/subdwarf/
Contact: subdwarf@ing.iac.es
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A new meeting series on hot subdwarf stars was started at Keele University in 2003. The meeting is an offspring of the long running biannual series of White Dwarf workshops. The intention is that the Subdwarf meetings will also run biannually, in the odd years between the WD meetings. The aim of the workshop series is to disseminate recent results on the properties, formation, and evolution of the hot subdwarf stars and related objects, and to assess the impact of these results on other areas of astrophysics (see below for a full scientific background). The second meeting on hot subdwarf stars and related objects will be held in Santa Cruz de La Palma on the Canary Islands, and is organised in collaboration by the Isaac Newton Group of Telescopes and the Nordic Optical Telescope.
A preliminary list of session topics:
* Evolutionary models and the UV-upturn phenomenon
* Hot subdwarfs and hot HB stars in the field, clusters and galaxies
* Hot subdwarfs in binary systems
* Atmospheric properties of hot subdwarf stars
* Asteroseismology of sdB stars
* Progenitors and progeny of sdB stars
IMPORTANT: The registration deadline is April 1, 2005.
Please reply to this email, or send a mail to subdwarf@ing.iac.es if you are interested in further information and would like to remain on our mailing list.
The registration opens on the 1st of December, and you should make your registration as soon as possible. Titles and abstracts of talks and posters can be submitted at any time up to the registration deadline. The registration fee is 150 Euro, to be paid on arrival at the meeting. Students can apply for a registration fee waiver. To register, complete the on-line registration form on our web-pages:
http://www.ing.iac.es/conferences/subdwarf/
Please pass on this announcement to any of your colleagues who may like to attend the workshop but who we have missed from this mailing list.
Scientific background
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Hot subdwarf stars are extreme horizontal branch (EHB) stars and pre-white dwarf stars. The EHB stars are core helium-burning stars with extremely thin hydrogen envelopes, and form the majority of bright stars in surveys for extremely blue objects, where they are classified as subdwarf-B (sdB) stars. They also appear in the colour-magnitude diagrams of some globular clusters as an extension of the blue tail formed by classical horizontal branch (HB) stars, though it is not clear why some clusters show this feature and other do not. The pre-white dwarf stars are related to the sdBs, but have exhausted their capacity to burn helium in the core. Many of the brightest hot subdwarfs in the field are of this class, and they are classified as sdO stars.
Hot subdwarf stars and their relatives are believed to be important contributors to the hitherto mysterious UV upturn phenomenon in early-type galaxies; and a comprehensive investigation on this issue is being performed by the Galaxy Evolution Explorer (GALEX). The formation of EHB stars remains, in general, a matter of debate. Recent results for Galactic EHB stars show that the majority are close binary stars, so mass transfer and mass loss due to interactions between the stars clearly play a role. EHB stars are an excellent tool for studying evolution in close binary stars. Some EHB stars shows p-mode pulsations with periods of a few minutes and some others show g-mode pulsations with periods on the order of hours. Asteroseismology can be used to measure fundamental parameters for these stars directly. Hot subdwarf stars are also a laboratory for studying the effects of diffusion, weak stellar winds, radiative levitation and gravitational settling. These processes are seen to affect the peculiar composition of their atmospheres and also play a role in the driving mechanism for pulsations and, perhaps, the subsequent evolution of the star.
Scientific Organising Committee
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Uli Heber, Bamberg
Simon Jeffery, Armagh
Sabine Moehler, Kiel
Pierre Maxted, Keele
Ralf Napiwotzki, Leicester
Roy Ostensen, La Palma
Philipp Podsiadlowski, Oxford
Jan-Erik Solheim, Oslo
Francois Wesemael, Montreal
Sukyoung Yi, Oxford
On behalf of the Local Organising Committee,
Roy Østensen