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A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars

Stello, Dennis and Cantiello, Matteo and Fuller, Jim and Huber, Daniel and García, Rafael A. and Bedding, Timothy R. and Bildsten, Lars and Silva Aguirre, Victor (2016) A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars. Nature, 529 (7586). pp. 364-367. ISSN 0028-0836. https://resolver.caltech.edu/CaltechAUTHORS:20160111-115935876

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Abstract

Magnetic fields play a part in almost all stages of stellar evolution. Most low-mass stars, including the Sun, show surface fields that are generated by dynamo processes in their convective envelopes. Intermediate-mass stars do not have deep convective envelopes, although 10 per cent exhibit strong surface fields that are presumed to be residuals from the star formation process. These stars do have convective cores that might produce internal magnetic fields, and these fields might survive into later stages of stellar evolution, but information has been limited by our inability to measure the fields below the stellar surface. Here we report the strength of dipolar oscillation modes for a sample of 3,600 red giant stars. About 20 per cent of our sample show mode suppression, by strong magnetic fields in the cores, but this fraction is a strong function of mass. Strong core fields occur only in red giants heavier than 1.1 solar masses, and the occurrence rate is at least 50 per cent for intermediate-mass stars (1.6–2.0 solar masses), indicating that powerful dynamos were very common in the previously convective cores of these stars.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1038/nature16171DOIArticle
http://arxiv.org/abs/1601.00004arXivDiscussion Paper
http://rdcu.be/fPeDPublisherFree ReadCube access
ORCID:
AuthorORCID
Cantiello, Matteo0000-0002-8171-8596
Fuller, Jim0000-0002-4544-0750
Huber, Daniel0000-0001-8832-4488
Bedding, Timothy R.0000-0001-5222-4661
Additional Information:© 2016 Macmillan Publishers Limited. received 25 June; accepted 15 October 2015. Published online 4 January 2016. This paper has been written collaboratively, on the web, using Authorea (http://www.authorea.com). We acknowledge the entire Kepler team, whose efforts made these results possible. D.S. is the recipient of an Australian Research Council Future Fellowship (project number FT140100147). J.F. acknowledges support from NSF under grant number AST-1205732 and through a Lee DuBridge Fellowship at Caltech. R.A.G. acknowledges the support of the European Community’s Seventh Framework Programme (FP7/2007–2013) under grant agreement number 269194 (IRSES/ASK), the CNES, and the ANR-12-BS05-0008, IDEE. D.H. acknowledges support by the Australian Research Council’s Discovery Projects funding scheme (project number DE140101364) and support by the National Aeronautics and Space Administration under grant number NNX14AB92G issued through the Kepler Participating Scientist Program. This project was supported by NASA under TCAN grant number NNX14AB53G, and by the NSF under grant numbers PHY11-25915 and AST11-09174. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (grant agreement number DNRF106). The research is supported by the ASTERISK project (ASTERoseismic Investigations with SONG and Kepler) funded by the European Research Council (grant agreement number 267864). Contributions: D.S. measured and interpreted mode visibilities; M.C. and J.F. calculated and interpreted theoretical models; D.H. and D.S. calculated power spectra and measured large frequency separations; R.A.G., T.R.B., L.B. and V.S.A. contributed to the discussion of the results. All authors commented on the manuscript. The authors declare no competing financial interests.
Group:TAPIR, Walter Burke Institute for Theoretical Physics
Funders:
Funding AgencyGrant Number
NSFAST-1205732
Lee A. DuBridge FoundationUNSPECIFIED
European Commission’s Seventh Framework Programme FP7/2007-2013269194
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Agence Nationale pour la Recherche (ANR)ANR-12-BS05-0008
Australian Research CouncilDE140101364
NASANNX14AB92G
NASANNX14AB53G
NSFPHY11-25915
NSFAST11-09174
Danish National Research FoundationDNRF106
European Research Council (ERC)267864
Issue or Number:7586
Record Number:CaltechAUTHORS:20160111-115935876
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160111-115935876
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63549
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:13 Jan 2016 00:02
Last Modified:22 Apr 2020 19:41

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