TY - JOUR
T1 - Magnetic field, differential rotation and activity of the hot-Jupiter-hosting star HD 179949
AU - Fares, R.
AU - Donati, J. F.
AU - Moutou, C.
AU - Jardine, M.
AU - Cameron, A. C.
AU - Lanza, A. F.
AU - Bohlender, D.
AU - Dieters, S.
AU - Martínez Fiorenzano, A. F.
AU - Maggio, A.
AU - Pagano, I.
AU - Shkolnik, E. L.
PY - 2012/6
Y1 - 2012/6
N2 - HD 179949 is an F8V star, orbited by a giant planet at ∼8R{black star} 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 ± 0.061radd-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.
AB - HD 179949 is an F8V star, orbited by a giant planet at ∼8R{black star} 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 ± 0.061radd-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.
KW - Planet-star interactions
KW - Stars: activity
KW - Stars: individual: HD 179949
KW - Stars: magnetic fields
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U2 - 10.1111/j.1365-2966.2012.20780.x
DO - 10.1111/j.1365-2966.2012.20780.x
M3 - Article
AN - SCOPUS:84862117065
SN - 0035-8711
VL - 423
SP - 1006
EP - 1017
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 2
ER -