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Published June 10, 2016 | Published + Submitted
Journal Article Open

Asteroseismic signatures of evolving internal stellar magnetic fields

Abstract

Recent asteroseismic analyses indicate the presence of strong (B ≳ 10^5 G) magnetic fields in the cores of many red giant stars. Here, we examine the implications of these results for the evolution of stellar magnetic fields, and we make predictions for future observations. Those stars with suppressed dipole modes indicative of strong core fields should exhibit moderate but detectable quadrupole mode suppression. The long magnetic diffusion times within stellar cores ensure that dynamo-generated fields are confined to mass coordinates within the main-sequence (MS) convective core, and the observed sharp increase in dipole mode suppression rates above 1.5 M_⊙ is likely explained by the larger convective core masses and faster rotation of these more massive stars. In clump stars, core fields of ~10^5 G can suppress dipole modes, whose visibility should be equal to or less than the visibility of suppressed modes in ascending red giants. High dipole mode suppression rates in low-mass (M ≾ 2 M_⊙) clump stars would indicate that magnetic fields generated during the MS can withstand subsequent convective phases and survive into the compact remnant phase. Finally, we discuss implications for observed magnetic fields in white dwarfs and neutron stars, as well as the effects of magnetic fields in various types of pulsating stars.

Additional Information

© 2016 The American Astronomical Society. Received 2016 February 8; accepted 2016 March 28; published 2016 June 3. This paper was written collaboratively, on the Web, using Authorea (https://www.authorea.com). We thank Bill Paxton, Dennis Stello, Rafa Garcia, Jamie Lloyd, Evan Bauer, J. J. Hermes, Benoît Mosser, and all the members of the SPIDER collaboration for helpful discussions and suggestions. J.F. acknowledges partial support from NSF under grant no. AST-1205732 and through a Lee DuBridge Fellowship at Caltech. This research was supported by the National Science Foundation under grant no. NSF PHY11-25915 and AST 11-09174, and by NASA under TCAN grant no. NNX14AB53G.

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Published - apj_824_1_14.pdf

Submitted - 1602.03056v1.pdf

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