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A Model for Stellar Convection and Spectral Line Asymmetries

Published online by Cambridge University Press:  08 February 2017

H. M. Antia
H. M. Antia*
Affiliation:
Tata Institute of Fundamental Research Homi Bhabha Road, Bombay 400 005, INDIA

Abstract

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A model for stellar convection zones based on linear convective modes using a nonlocal mixing length theory is developed to study the spectral line asymmetries and the line shifts resulting from convective motions in the stellar photospheric region. The amplitudes of these linear convective modes is estimated by requiring the convective flux due to a linear superposition of such modes to reproduce the convective flux in the mixing length model. To study the spectral line asymmetries the convective mode with the largest amplitude in the photospheric line formation region is chosen to represent the stellar velocity field and the accompanying intensity fluctuations. Synthetic spectral line profiles are obtained by summing locally symmetric profiles over the stellar disk according to the local Doppler velocity and intensity fluctuations. The resulting line bisector shapes and the line shifts are compared with observations for α-Cen B. It is found that while the simple model proposed here can explain either the line shifts or the line bisector shape reasonably well, it fails to explain both these characteristics simultaneously.

Type
VII. Convection and Magnetic Fields in Solar-type Stars
Information
Symposium - International Astronomical Union , Volume 138: Solar Photosphere: Structure, Convection and Magnetic Fields , 1990 , pp. 417 - 420
Copyright
Copyright © Kluwer 1990 

References

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