Abstract

A. Ulla¹, P. Thejll², J. MacDonald³, Fernando Pérez Hernández^4,5, R. Oreiro Rey^1,5, M.R. Zapatero Osorio⁶, R. García López^4,5, R.A. Saffer⁷, M. Manteiga⁸, A. Ferriz-Mas¹, V. Elkin⁹, J.M. González Pérez¹⁰

¹ Departamento de Física Aplicada, Universidade de Vigo, E-36200 Vigo (Spain)
² Danmarks Meteorologiske Institut, DK-2100 København (Denmark)
³ Department of Physics and Astronomy, Delaware University (USA)
⁴ Instituto de Astrofísica de Canarias, E-38200 La Laguna (Spain)
⁵ Departamento de Astrofísica, Universidad de La Laguna, E-38200 La Laguna (Spain)
⁶ Laboratorio de Astrofísica Espacial y Física Fundamental, E-28080 Madrid (Spain)
⁷ Department of Astronomy \& Astrophysics, Villanova University (USA)
⁸ Departamento de Ciencias de la Navegación y de la Tierra, Universidade da Coruña, E-15011 A Coruña (Spain)
⁹ Special Astrophysical Observatory, Russian Academy of Sciences, 357 147 Nizhnij Arkhyz (Russia)
¹⁰ Nordlysobservatoriet, Universitetet i Tromsö, N-9037 Tromsö (Norway)

Hot subdwarf stars (hot sds) are blue subluminous objects at high galactic latitudes. They split into two well separated spectroscopic sequences: the O (sdOs) and B-type (sdBs), according to composition and effective temperature. As they are likely immediate progenitors of white dwarfs (WDs), this resembles, although not as cleanly, the existing spectroscopic division of these into H (DA) / He (DB) WD subclasses. Among the various theories for the origin and final fate of hot sds, single and close binary evolution have both been suggested but the issue is still strongly debated. Only a few determinations are available to date regarding the study of such aspects as rotation and microturbulent velocities or the magnetic nature of these objects. Over 25 sdBs are known to date to be multiperiodic rapid oscillators. We present preliminary results of new observations and models of a sample of pulsating and non-pulsating hot subdwarfs, including considerations on mass loss and magnetic properties.