Abstract
Context. HD 179949 is an F8V star, orbited by a close-in giant planet with a period of ∼3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot spot which rotates in phase with the planet orbit. However, this phenomenon is intermittent since it was observed in several but not all seasons. Aims. A long-term monitoring of the magnetic activity of HD 179949 is required to study the amplitude and time scales of star-planet interactions. Methods. In 2009 we performed a simultaneous optical and X-ray spectroscopic campaign to monitor the magnetic activity of HD 179949 during ∼5 orbital periods and ∼2 stellar rotations. We analyzed the Ca ii H&K lines as a proxy for chromospheric activity, and we studied the X-ray emission in search of flux modulations and to determine basic properties of the coronal plasma. Results. A detailed analysis of the flux in the cores of the Ca ii H&K lines and a similar study of the X-ray photometry shows evidence of source variability, including one flare. The analysis of the time series of chromospheric data indicates a modulation with a ∼11 days period, compatible with the stellar rotation period at high latitudes. Instead, the X-ray light curve suggests a signal with a period of ∼4 days, consistent with the presence of two active regions on opposite hemispheres. Conclusions. The observed variability can be explained, most likely, as due to rotational modulation and to intrinsic evolution of chromospheric and coronal activity. There is no clear signature related to the orbital motion of the planet, but the possibility that just a fraction of the chromospheric and coronal variability is modulated with the orbital period of the planet, or the stellar-planet beat period, cannot be excluded. We conclude that any effect due to the presence of the planet is difficult to disentangle.
| Original language | English (US) |
|---|---|
| Article number | A7 |
| Journal | Astronomy and Astrophysics |
| Volume | 552 |
| DOIs | |
| State | Published - 2013 |
| Externally published | Yes |
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Keywords
- Planet-star interactions
- Stars: activity
- Stars: magnetic field
- Stars: solar-type
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
Cite this
A coordinated optical and X-ray spectroscopic campaign on HD 179949 : Searching for planet-induced chromospheric and coronal activity. / Scandariato, G.; Maggio, A.; Lanza, A. F.; Pagano, I.; Fares, R.; Shkolnik, Evgenya; Bohlender, D.; Cameron, A. C.; Dieters, S.; Donati, J. F.; Martínez Fiorenzano, A. F.; Jardine, M.; Moutou, C.
In: Astronomy and Astrophysics, Vol. 552, A7, 2013.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A coordinated optical and X-ray spectroscopic campaign on HD 179949
T2 - Searching for planet-induced chromospheric and coronal activity
AU - Scandariato, G.
AU - Maggio, A.
AU - Lanza, A. F.
AU - Pagano, I.
AU - Fares, R.
AU - Shkolnik, Evgenya
AU - Bohlender, D.
AU - Cameron, A. C.
AU - Dieters, S.
AU - Donati, J. F.
AU - Martínez Fiorenzano, A. F.
AU - Jardine, M.
AU - Moutou, C.
PY - 2013
Y1 - 2013
N2 - Context. HD 179949 is an F8V star, orbited by a close-in giant planet with a period of ∼3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot spot which rotates in phase with the planet orbit. However, this phenomenon is intermittent since it was observed in several but not all seasons. Aims. A long-term monitoring of the magnetic activity of HD 179949 is required to study the amplitude and time scales of star-planet interactions. Methods. In 2009 we performed a simultaneous optical and X-ray spectroscopic campaign to monitor the magnetic activity of HD 179949 during ∼5 orbital periods and ∼2 stellar rotations. We analyzed the Ca ii H&K lines as a proxy for chromospheric activity, and we studied the X-ray emission in search of flux modulations and to determine basic properties of the coronal plasma. Results. A detailed analysis of the flux in the cores of the Ca ii H&K lines and a similar study of the X-ray photometry shows evidence of source variability, including one flare. The analysis of the time series of chromospheric data indicates a modulation with a ∼11 days period, compatible with the stellar rotation period at high latitudes. Instead, the X-ray light curve suggests a signal with a period of ∼4 days, consistent with the presence of two active regions on opposite hemispheres. Conclusions. The observed variability can be explained, most likely, as due to rotational modulation and to intrinsic evolution of chromospheric and coronal activity. There is no clear signature related to the orbital motion of the planet, but the possibility that just a fraction of the chromospheric and coronal variability is modulated with the orbital period of the planet, or the stellar-planet beat period, cannot be excluded. We conclude that any effect due to the presence of the planet is difficult to disentangle.
AB - Context. HD 179949 is an F8V star, orbited by a close-in giant planet with a period of ∼3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot spot which rotates in phase with the planet orbit. However, this phenomenon is intermittent since it was observed in several but not all seasons. Aims. A long-term monitoring of the magnetic activity of HD 179949 is required to study the amplitude and time scales of star-planet interactions. Methods. In 2009 we performed a simultaneous optical and X-ray spectroscopic campaign to monitor the magnetic activity of HD 179949 during ∼5 orbital periods and ∼2 stellar rotations. We analyzed the Ca ii H&K lines as a proxy for chromospheric activity, and we studied the X-ray emission in search of flux modulations and to determine basic properties of the coronal plasma. Results. A detailed analysis of the flux in the cores of the Ca ii H&K lines and a similar study of the X-ray photometry shows evidence of source variability, including one flare. The analysis of the time series of chromospheric data indicates a modulation with a ∼11 days period, compatible with the stellar rotation period at high latitudes. Instead, the X-ray light curve suggests a signal with a period of ∼4 days, consistent with the presence of two active regions on opposite hemispheres. Conclusions. The observed variability can be explained, most likely, as due to rotational modulation and to intrinsic evolution of chromospheric and coronal activity. There is no clear signature related to the orbital motion of the planet, but the possibility that just a fraction of the chromospheric and coronal variability is modulated with the orbital period of the planet, or the stellar-planet beat period, cannot be excluded. We conclude that any effect due to the presence of the planet is difficult to disentangle.
KW - Planet-star interactions
KW - Stars: activity
KW - Stars: magnetic field
KW - Stars: solar-type
UR - http://www.scopus.com/inward/record.url?scp=84874848522&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84874848522&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201219875
DO - 10.1051/0004-6361/201219875
M3 - Article
AN - SCOPUS:84874848522
VL - 552
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A7
ER -