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

Citation

Fares, R and Donati, J-F and Moutou, C and Jardine, M and Cameron, AC and Lanza, AF and Bohlender, D and Dieters, S and Martinez Fiorenzano, AF and Maggio, A and Pagano, I and Shkolnik, EL, Magnetic field, differential rotation and activity of the hot-Jupiter-hosting star HD 179949, Monthly Notices of the Royal Astronomical Society, 423, (2) pp. 1006-1017. ISSN 0035-8711 (2012) [Refereed Article]

Copyright Statement

Copyright 2012 The Authors

DOI: doi:10.1111/j.1365-2966.2012.20780.x

Abstract

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.

Item Details

Item Type:Refereed Article
Keywords:planet-star interactions - stars: activity - stars: individual: HD 179949 - stars: magnetic fields
Research Division:Physical Sciences
Research Group:Astronomical and Space Sciences
Research Field:Galactic Astronomy
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Physical Sciences
Author:Dieters, S (Dr Stefan Dieters)
ID Code:83326
Year Published:2012
Web of Science® Times Cited:29
Deposited By:Mathematics and Physics
Deposited On:2013-03-08
Last Modified:2013-07-01
Downloads:0

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