This paper will mainly introduce some studies of pulsating subdwarf B stars, Itinculdes two aspects of asteroseismology studies of pulsating subdwarf B stars. Firstly, this paper introduces the influence of the He-flash convective overshooton mode trapping efficiency in g-mode pulsating subdwarf B stars. Recent detectionsof g-mode pulsations in subdwarf B (sdB) stars from the space missions CoRoT andKepler have verified that nearly all of these pulsators have regular period spacings.This discovery has been extensively applied to mode identification for the observedg-mode sdB pulsators. However, the discovery of regular period spacings apparentlydisobeys the strong g-mode trapping structure expected in canonical sdB models, whichare caused by steep chemical gradients in such evolved stars. Although the mode trappingefficiency could be reduced somewhat by taking into account the diffusion effectduring the sdB phase, it still seems difficult to explain the regular period spacings ofg-mode sdB pulsators, especially in the short period range. We suggest that the reasonfor regular period spacings may come from previous evolution of sdB stars rather thanduring the sdB stage. As for a canonical sdB model, it is evolved from a low-massstar and considered to have gone through the He-flash. The He-flash causes extensiveconvection on an aggressive way that extends very close to the He/H-transition zone.By considering a proper convective overshoot during the He-flash stage, the chemicalprofile in the He/H-transition zone would become more smooth. Detailed model calculationsshow that the mode trapping efficiency could be reduced approximatively to thelevel of observations in all the observed period range by taking the He-flash overshootinto account. Secondly, this paper introduces some asteroseismology methods to distinguish thecore and shell helium burning sdB stars. The sdB stars are generally considered as thecore helium burning stars. However, most canonical sdB models have shown that theyleave the sdB band (i.e. the region within 20000 Tef f 40000 and 5 log g 6:2)after they have ignited helium in the shell. This means there will be a few of the shellhelium burning stars, which have exhausted their helium in the core, may still locateon the sdB band and should be considered as sdB stars too. But because they haveclose effective temperature and gravity as the core helium burning sdB stars, we can notdistinguish the two kinds of sdB stars just by atmospheric parameters. A part of sdBstars display multimode pulsations. We thought that asteroseismology could offer somemethods to distinguish the two kinds of sdB stars. The core and shell helium burning sdBstars have some obvious differences in structure and evolutionary track, which resultsin some clear differences in their pulsation properties. So, we may distinguish them bytheir pulsation properties such as the rates of period change of the p-mode sdB pulsators,the numbers of mixed modes, and the period spacings of the g-mode sdB pulsators. Wesuggested that there are two special sdB stars (V 391 Pegasi and PG 1605+072) whichare likely the shell helium burning sdB stars.
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