G-mode trapping and period spacings in hot B subdwarf stars. Issue Volume 9:Issue S301(2013) (18th February 2014)

• Record Type: Journal Article
• Authors: Charpinet, S.; Van Grootel, V.; Brassard, P.; Fontaine, G.
• Is Part Of: Proceedings of the International Astronomical Union. Volume 9:Issue S301(2013)
• Page Start: 397
• Page End: 398
• Publication Date: 2014-02-18
• Subjects: stars: oscillations, -- stars: subdwarfs, -- stars: interiors; Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S1743921313014737
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: Hot B subdwarfs (sdB) are hot and compact helium core burning stars of nearly half a solar mass that can develop pulsational instabilities driving acoustic and/or gravity modes. These evolved stars are expected to be chemically stratified with an almost pure hydrogen envelope surrounding a helium mantle on top of a carbon/oxygen enriched core. However, the sdB stars pulsating in g-modes show regularities in their observed period distributions that, surprisingly (at first sight), are typical of the behavior of high order g-modes in chemically homogeneous (i.e., non-stratified) stars. This led to a claim that hot B subdwarfs could be much less chemically stratified than previously thought. Here, we reinvestigate trapping effects affecting g-modes in sdB stars. We show that standard stratified models of such stars can also produce nearly constant period spacings in the low frequency range similar to those found in g-mode spectra of sdB stars monitored with Kepler .