Discovery of a new class of pulsating stars: Gravity-mode pulsators among subdwarf B stars

Abstract

During the course of an ongoing CCD monitoring program to investigate low-level light variations in subdwarf B (sdB) stars, we serendipitously discovered a new class of multimode pulsators with periods of the order of an hour. These periods are a factor of ten longer than those of previously known multimode sdB pulsators (EC14026 stars), implying the new pulsations are due to gravity modes rather than pressure modes. The iron opacity instability that drives the short period EC 14026 stars is effective in hot sdB's. The long period pulsators are found only among cooler sdB stars, wherethey are surprisingly common. The mechanism responsible for exciting the deeper g-modes in cool sdB's is currently unknown, but the temperature and gravity range in which these stars occur must be an important clue. We present the first observational results for this new class of pulsating sdB stars, and discuss some possible implications.

Department(s)

Physics, Astronomy, and Materials Science

Document Type

Article

DOI

https://doi.org/10.1023/A:1023228427035

Keywords

gravity modes, pulsating sdB stars

Publication Date

12-1-2003

Journal Title

Astrophysics and Space Science

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