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Magnetic field, differential rotation and activity of the hot-Jupiter-hosting star HD 179949

journal contribution
posted on 2023-05-17, 16:33 authored by Fares, R, Donati, J-F, Moutou, C, Jardine, M, Cameron, AC, Lanza, AF, Bohlender, D, Dieters, S, Martinez Fiorenzano, AF, Maggio, A, Pagano, I, Shkolnik, EL

HD 179949 is an F8V star, orbited by a giant planet at ~8R every 3.092514 d. The system was reported to undergo episodes of stellar activity enhancement modulated by the orbital period, interpreted as caused by star-planet interactions (SPIs). One possible cause of SPIs is the large-scale magnetic field of the host star in which the close-in giant planet orbits.

In this paper we present spectropolarimetric observations of HD 179949 during two observing campaigns (2009 September and 2007 June). We detect a weak large-scale magnetic field of a few gauss at the surface of the star. The field configuration is mainly poloidal at both observing epochs. The star is found to rotate differentially, with a surface rotation shear of dΩ = 0.216 ± 0.061 rad d-1, corresponding to equatorial and polar rotation periods of 7.62 ± 0.07 and 10.3 ± 0.8d, respectively. The coronal field estimated by extrapolating the surface maps resembles a dipole tilted at ~70°. We also find that the chromospheric activity of HD 179949 is mainly modulated by the rotation of the star, with two clear maxima per rotation period as expected from a highly tilted magnetosphere. In 2009 September, we find that the activity of HD 179949 shows hints of low-amplitude fluctuations with a period close to the beat period of the system.

History

Publication title

Monthly Notices of the Royal Astronomical Society

Volume

423

Pagination

1006-1017

ISSN

0035-8711

Department/School

School of Natural Sciences

Publisher

Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 2012 The Authors

Repository Status

  • Restricted

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Expanding knowledge in the physical sciences

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