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Viscous and centrifugal instabilities of massive stars

Shi, Yanlong and Fuller, Jim (2022) Viscous and centrifugal instabilities of massive stars. Monthly Notices of the Royal Astronomical Society, 513 (1). pp. 1115-1128. ISSN 0035-8711. doi:10.1093/mnras/stac986. https://resolver.caltech.edu/CaltechAUTHORS:20220525-91380000

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Abstract

Massive stars exhibit a variety of instabilities, many of which are poorly understood. We explore instabilities induced by centrifugal forces and angular momentum transport in massive rotating stars. First, we derive and numerically solve linearized oscillation equations for adiabatic radial modes in polytropic stellar models. In the presence of differential rotation, we show that centrifugal and Coriolis forces combined with viscous angular momentum transport can excite stellar pulsation modes, under both low- or high-viscosity conditions. In the low-viscosity limit, which is common in real stars, we demonstrate how to compute mode growth/damping rates via a work integral. Finally, we build realistic rotating 30 M_⊙ star models and show that overstable (growing) radial modes are predicted to exist for most of the star’s life, in the absence of non-adiabatic effects. Peak growth rates are predicted to occur while the star is crossing the Hertzsprung–Russell gap, though non-adiabatic damping may dominate over viscous driving, depending on the effective viscosity produced by convective and/or magnetic torques. Viscous instability could be a new mechanism to drive massive star pulsations and is possibly related to instabilities of luminous blue variable stars.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stac986DOIArticle
https://arxiv.org/abs/2203.11809arXivDiscussion Paper
https://github.com/yanlongastro/polytropicRelated ItemScripts
ORCID:
AuthorORCID
Shi, Yanlong0000-0002-0087-3237
Fuller, Jim0000-0002-4544-0750
Additional Information:© 2022 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model). Accepted 2022 April 5. Received 2022 March 19; in original form 2021 November 23. JF is thankful for support through an Innovator Grant from The Rose Hills Foundation, and the Sloan Foundation through grant FG-2018-10515. DATA AVAILABILITY. Scripts involved in this work are available at https://github.com/yanlongastro/polytropic, or upon reasonable request to the authors.
Group:Astronomy Department
Funders:
Funding AgencyGrant Number
Rose Hills FoundationUNSPECIFIED
Alfred P. Sloan FoundationFG-2018-10515
Subject Keywords:instabilities, stars: evolution, stars: massive, stars: mass-loss, stars: rotation
Issue or Number:1
DOI:10.1093/mnras/stac986
Record Number:CaltechAUTHORS:20220525-91380000
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20220525-91380000
Official Citation:Yanlong Shi, Jim Fuller, Viscous and centrifugal instabilities of massive stars, Monthly Notices of the Royal Astronomical Society, Volume 513, Issue 1, June 2022, Pages 1115–1128, https://doi.org/10.1093/mnras/stac986
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114919
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:31 May 2022 16:25
Last Modified:31 May 2022 16:25

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