Rotation in sdB stars as revealed by stellar oscillations

Open Astronomy

Zong Weikai¹  Fontaine Gilles²  Brassard Pierre²  Giammichele Noemi³  Charpinet Stephane³  Van Grootel Valérie⁴ 

[1] Department of Astronomy, Beijing Normal University,Beijing100875, P. R. China;Département de Physique, Université de Montréal,Montréal, QC H3C 3J7, Canada;IRAP, Université de Toulouse, CNRS, UPS, CNES, 14 avenue Edouard Belin, F-31400Toulouse, France;Space sciences, Technologies sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, 19C Allée du six-août, B-4000Liège, Belgium;

关键词: subdwarfs;    stars:oscillation;    stars:rotation;    stars:evolution;   

DOI  :  10.1515/astro-2018-0012

来源: DOAJ

【 摘 要 】

An interesting opportunity offered by the detection of stellar oscillations is the possibility to infer the internal rotation rate of a star through the so-called rotational splittings. Such seismic measurements remained rather scarce for hot B subdwarf (sdB) stars until the advent of space observations with the Kepler spacecraft. Nowadays, however, a number of rotation measurements have become available, offering a glimpse on the global rotational properties of sdB stars. Here, we briefly discuss what asteroseismology starts to reveal on the rotation rate of these stars. We also make connections with the internal rotation of red-giant and white-dwarf stars. In particular, we show that the very slow rotation rates derived for single sdB stars, and their similarities with the dynamical properties of the cores of red-clump stars, strongly suggest that they evolved from red-giants rather than merger events.We also point out that no more angular momentum seems to be lost by stellar cores throughout the helium burning phase until the cooling white-dwarf stage, indicating that all the braking occurs before, most likely during red-giant branch evolution.

【 授权许可】

Unknown