A coordinated optical and X-ray spectroscopic campaign on HD 179949: Searching for planet-induced chromospheric and coronal activity

G. Scandariato, A. Maggio, A. F. Lanza, I. Pagano, R. Fares, Evgenya Shkolnik, D. Bohlender, A. C. Cameron, S. Dieters, J. F. Donati, A. F. Martínez Fiorenzano, M. Jardine, C. Moutou

Research output: Contribution to journalArticle

18 Citations (Scopus)

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 languageEnglish (US)
Article numberA7
JournalAstronomy and Astrophysics
Volume552
DOIs
StatePublished - 2013
Externally publishedYes

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planets
planet
x rays
stellar rotation
K lines
modulation
stars
orbits
orbitals
hemispheres
polar regions
flares
light curve
photometry
synchronism
signatures
time series
timescale
plasma
monitoring

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 journalArticle

Scandariato, G, Maggio, A, Lanza, AF, Pagano, I, Fares, R, Shkolnik, E, Bohlender, D, Cameron, AC, Dieters, S, Donati, JF, Martínez Fiorenzano, AF, Jardine, M & Moutou, C 2013, 'A coordinated optical and X-ray spectroscopic campaign on HD 179949: Searching for planet-induced chromospheric and coronal activity', Astronomy and Astrophysics, vol. 552, A7. https://doi.org/10.1051/0004-6361/201219875
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. / A coordinated optical and X-ray spectroscopic campaign on HD 179949 : Searching for planet-induced chromospheric and coronal activity. In: Astronomy and Astrophysics. 2013 ; Vol. 552.
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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.",
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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

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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.

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KW - Stars: activity

KW - Stars: magnetic field

KW - Stars: solar-type

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