Abstract
Non-radial pulsations in Extreme Horizontal Branch stars (also known as hot B subdwarfs or sdB stars) offer strong opportunities to study, through asteroseismology, the structure and internal dynamics of stars in this intermediate stage of stellar evolution. Most sdB stars directly descend from former red giants and are expected to evolve straight into white dwarfs after core helium exhaustion. They thus represent the most direct link between these two stages. Their properties should therefore reflect both the outcome of the core evolution of red giant stars and the initial state for a fraction of the white dwarfs. We review the status of this field after a decade of efforts to exploit both p-mode and g-mode pulsating sdB stars as asteroseismic laboratories. From the discoveries of these two classes of pulsators in 1997 and 2003, respectively, up to the current epoch of data gathering of unprecedented quality from space, a lot of progress has been made in this area and prospects for future achievements look very promising.
Highlights
Most hot B subdwarf stars are believed to be former red giant stars that have lost all but a tiny fraction of their H-rich envelope during or just before the onset of helium burning in the core
Most sdB stars directly descend from former red giants and are expected to evolve straight into white dwarfs after core helium exhaustion
Hot subdwarfs evolve directly to the white dwarf stage without experiencing another red giant phase as most other horizontal branch stars do after core helium exhaustion
Summary
Most hot B subdwarf (sdB) stars (see [1] for a complete review) are believed to be former red giant stars that have lost all but a tiny fraction of their H-rich envelope during or just before the onset of helium burning in the core. Important observational efforts to detect and characterize the oscillations in sdB stars have been made during the past decade These include surveys to find the pulsators [4, 9, 10], dedicated groundbased white light photometric campaigns to provide key data for asteroseismology [11, 12] (see Fig. 2), attempts to identify modes through multicolor photometry [13,14,15] and time resolved spectroscopy [16, 17], and most recently ultra high precision photometry from space with CoRoT [18] and Kepler [19, 20] (see Fig. 2).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
