A New C-D-like Diagram for SPB Stars: The Variations of Period Spacing as a Signature of Evolutionary Status

The slowly pulsating B-type (SPB) stars are the upper main-sequence stars on the HR diagram. Their oscillations are high-order, low-degree g-mode and can be used to probe the structure of the radiative zone near the outer boundary of the convective core and constrain the chemical mixing in stellar i...

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Bibliographic Details
Published in:The Astrophysical journal 2018-11, Vol.867 (1), p.47
Main Authors: Wu, Tao, Li, Yan, Deng, Zhen-min
Format: Article
Language:English
Subjects:
asteroseismology
Astrophysics
Chemical composition
Frequency variation
Hydrogen
Main sequence stars
Organic chemistry
stars: fundamental parameters
stars: individual (HD 50230, KIC 6462030, KIC 8324482, and KIC 10526294)
stars: interiors
stars: oscillations
Stellar evolution
Stellar interiors
Stellar mass
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Summary:The slowly pulsating B-type (SPB) stars are the upper main-sequence stars on the HR diagram. Their oscillations are high-order, low-degree g-mode and can be used to probe the structure of the radiative zone near the outer boundary of the convective core and constrain the chemical mixing in stellar interiors. In SPB stars, the period spacing periodically varies with periods. It has been regarded as a signature of the chemical composition gradient beyond the convective core. Based on theoretical calculations, we find that the variation frequency of the period spacings (fΔP) is related to the width of the -gradient region on the buoyancy radius (Λ ) with the relation of fΔP ∼ 0.5Λ . This indicates that the variation frequency fΔP is sensitive to the central hydrogen mass fraction XC (i.e., the evolutionary status). Finally, we find that the variation frequency fΔP and the means of the period spacings can be used to construct a new C-D-like diagram (fΔP versus ), which can be used to roughly decide the stellar evolutionary stages and to approximately determine stellar mass for SPB stars.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aadf85