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  LBT/PEPSI Spectropolarimetry of a Magnetic Morphology Shift in Old Solar-type Stars

Metcalfe, T. S., Kochukhov, O., Ilyin, I. V., Strassmeier, K. G., Godoy-Rivera, D., & Pinsonneault, M. H. (2019). LBT/PEPSI Spectropolarimetry of a Magnetic Morphology Shift in Old Solar-type Stars. Astrophysical Journal, Letters, 887(2):. doi:10.3847/2041-8213/ab5e48.

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アイテムのパーマリンク: https://hdl.handle.net/21.11116/0000-0006-71F8-3 版のパーマリンク: https://hdl.handle.net/21.11116/0000-0007-815E-E
資料種別: 学術論文

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 作成者:
Metcalfe, T. S.1, 著者
Kochukhov, O., 著者
Ilyin, I. V., 著者
Strassmeier, K. G., 著者
Godoy-Rivera, D., 著者
Pinsonneault, M. H., 著者
所属:
1Department Solar and Stellar Interiors, Max Planck Institute for Solar System Research, Max Planck Society, Justus-von-Liebig-Weg 3, 37077 Göttingen, DE, ou_1832287              

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 要旨: Solar-type stars are born with relatively rapid rotation and strong magnetic fields. Through a process known as magnetic braking, the rotation slows over time as stellar winds gradually remove angular momentum from the system. The rate of angular momentum loss depends sensitively on the magnetic morphology, with the dipole field exerting the largest torque on the star. Recent observations suggest that the efficiency of magnetic braking may decrease dramatically in stars near the middle of their main-sequence lifetimes. One hypothesis to explain this reduction in efficiency is a shift in magnetic morphology from predominantly larger to smaller spatial scales. We aim to test this hypothesis with spectropolarimetric measurements of two stars that sample chromospheric activity levels on opposite sides of the proposed magnetic transition. As predicted, the more active star (HD 100180) exhibits a significant circular polarization signature due to a nonaxisymmetric large-scale magnetic field, while the less active star (HD 143761) shows no significant signal. We identify analogs of the two stars among a sample of well-characterized Kepler targets, and we predict that the asteroseismic age of HD 143761 from future Transiting Exoplanet Survey Satellite observations will substantially exceed the age expected from gyrochronology. We conclude that a shift in magnetic morphology likely contributes to the loss of magnetic braking in middle-aged stars, which appears to coincide with the shutdown of their global dynamos.

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言語: eng - English
 日付: 2019
 出版の状態: 出版
 ページ: -
 出版情報: -
 目次: -
 査読: 査読あり
 識別子(DOI, ISBNなど): DOI: 10.3847/2041-8213/ab5e48
 学位: -

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出版物 1

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出版物名: Astrophysical Journal, Letters
  その他 : ApJL
種別: 学術雑誌
 著者・編者:
所属:
出版社, 出版地: Bristol, UK : Institute of Physics Publishing (IOP)
ページ: - 巻号: 887 (2) 通巻号: L38 開始・終了ページ: - 識別子(ISBN, ISSN, DOIなど): ISSN: 0004-637X
CoNE: https://pure.mpg.de/cone/journals/resource/954922828215_1