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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): L38. doi:10.3847/2041-8213/ab5e48.

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Datensatz-Permalink: https://hdl.handle.net/21.11116/0000-0006-71F8-3 Versions-Permalink: https://hdl.handle.net/21.11116/0000-0007-815E-E
Genre: Zeitschriftenartikel

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 Urheber:
Metcalfe, T. S.1, Autor
Kochukhov, O., Autor
Ilyin, I. V., Autor
Strassmeier, K. G., Autor
Godoy-Rivera, D., Autor
Pinsonneault, M. H., Autor
Affiliations:
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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Schlagwörter: -
 Zusammenfassung: 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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Sprache(n): eng - English
 Datum: 2019
 Publikationsstatus: Erschienen
 Seiten: -
 Ort, Verlag, Ausgabe: -
 Inhaltsverzeichnis: -
 Art der Begutachtung: Expertenbegutachtung
 Identifikatoren: DOI: 10.3847/2041-8213/ab5e48
 Art des Abschluß: -

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Titel: Astrophysical Journal, Letters
  Andere : ApJL
Genre der Quelle: Zeitschrift
 Urheber:
Affiliations:
Ort, Verlag, Ausgabe: Bristol, UK : Institute of Physics Publishing (IOP)
Seiten: - Band / Heft: 887 (2) Artikelnummer: L38 Start- / Endseite: - Identifikator: ISSN: 0004-637X
CoNE: https://pure.mpg.de/cone/journals/resource/954922828215_1