Proceedings of the International Astronomical Union
The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. ... more The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. The detection of activity cycles in solar-like stars and the study of their properties allow us to put the solar dynamo in perspective, investigating how dynamo action depends on stellar parameters and stellar structure. Nevertheless, the lack of spatial resolution and the limited time extension of stellar data pose limitations to our understanding of stellar cycles and the possibility to constrain dynamo models. I briefly review some results obtained from disc-integrated proxies of stellar magnetic fields and discuss the new opportunities opened by space-borne photometry made available by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or spectropolarimetric observations. Stellar cycles have a significant impact on the energetic output and circumstellar magnetic fields of late-type active stars which affects the interaction between stars and their planets. On the ot...
Proceedings of the International Astronomical Union
The photospheric spot activity of some of the stars with transiting planets discovered by the CoR... more The photospheric spot activity of some of the stars with transiting planets discovered by the CoRoT space experiment is reviewed. Their out-of-transit light modulations are fitted by a spot model previously tested with the total solar irradiance variations. This approach allows us to study the longitude distribution of the spotted area and its variations versus time during the five months of a typical CoRoT time series. The migration of the spots in longitude provides a lower limit for the surface differential rotation, while the variation of the total spotted area can be used to search for short-term cycles akin the solar Rieger cycles. The possible impact of a close-in giant planet on stellar activity is also discussed.
... INAF-Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95125 Catania, Italy, e-mail:nucc... more ... INAF-Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95125 Catania, Italy, e-mail:nuccio.lanza@oact.inaf.it 1 Page 2. 2 ... (2009)], while [Jiménez-Reyes et al. (2003)] have presented the variation of the amplitude and FWHM of the mode peaks in the power spectrum. ...
Symposium - International Astronomical Union, 2004
The connection between orbital period variation and magnetic activity cyclic behaviour in close b... more The connection between orbital period variation and magnetic activity cyclic behaviour in close binaries with late-type components is addressed by discussing recent observational studies of Algols, RS…
We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most brig... more We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most bright members of the RS CVn class of magnetically active binary systems. Intermediate-resolution optical spectroscopy and IUE archive spectra were used to build radial-velocity curves yielding epochs of superior conjunction with an accuracy of 0.01 days. The final database ranged from 1976 to 2002 and allowed us a better assessment of the amplitude of the orbital period variation and its timescale. (2 data files).
Stars interact with their planets through gravitation, radiation, and magnetic fields. I shall fo... more Stars interact with their planets through gravitation, radiation, and magnetic fields. I shall focus on the interactions between late-type stars with an outer convection zone and close-in planets, i.e., with an orbital semimajor axis smaller than approximately 0.15 AU. I shall review the roles of tides and magnetic fields considering some key observations and discussing theoretical scenarios for their interpretation with an emphasis on open questions.
Proceedings of the International Astronomical Union
The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. ... more The solar activity cycle is a manifestation of the hydromagnetic dynamo working inside our star. The detection of activity cycles in solar-like stars and the study of their properties allow us to put the solar dynamo in perspective, investigating how dynamo action depends on stellar parameters and stellar structure. Nevertheless, the lack of spatial resolution and the limited time extension of stellar data pose limitations to our understanding of stellar cycles and the possibility to constrain dynamo models. I briefly review some results obtained from disc-integrated proxies of stellar magnetic fields and discuss the new opportunities opened by space-borne photometry made available by MOST, CoRoT, Kepler, and GAIA, and by new ground-based spectroscopic or spectropolarimetric observations. Stellar cycles have a significant impact on the energetic output and circumstellar magnetic fields of late-type active stars which affects the interaction between stars and their planets. On the ot...
Proceedings of the International Astronomical Union
The photospheric spot activity of some of the stars with transiting planets discovered by the CoR... more The photospheric spot activity of some of the stars with transiting planets discovered by the CoRoT space experiment is reviewed. Their out-of-transit light modulations are fitted by a spot model previously tested with the total solar irradiance variations. This approach allows us to study the longitude distribution of the spotted area and its variations versus time during the five months of a typical CoRoT time series. The migration of the spots in longitude provides a lower limit for the surface differential rotation, while the variation of the total spotted area can be used to search for short-term cycles akin the solar Rieger cycles. The possible impact of a close-in giant planet on stellar activity is also discussed.
... INAF-Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95125 Catania, Italy, e-mail:nucc... more ... INAF-Osservatorio Astrofisico di Catania, via S. Sofia, 78, 95125 Catania, Italy, e-mail:nuccio.lanza@oact.inaf.it 1 Page 2. 2 ... (2009)], while [Jiménez-Reyes et al. (2003)] have presented the variation of the amplitude and FWHM of the mode peaks in the power spectrum. ...
Symposium - International Astronomical Union, 2004
The connection between orbital period variation and magnetic activity cyclic behaviour in close b... more The connection between orbital period variation and magnetic activity cyclic behaviour in close binaries with late-type components is addressed by discussing recent observational studies of Algols, RS…
We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most brig... more We studied orbital period changes in the non-eclipsing close binary HR 1099, one of the most bright members of the RS CVn class of magnetically active binary systems. Intermediate-resolution optical spectroscopy and IUE archive spectra were used to build radial-velocity curves yielding epochs of superior conjunction with an accuracy of 0.01 days. The final database ranged from 1976 to 2002 and allowed us a better assessment of the amplitude of the orbital period variation and its timescale. (2 data files).
Stars interact with their planets through gravitation, radiation, and magnetic fields. I shall fo... more Stars interact with their planets through gravitation, radiation, and magnetic fields. I shall focus on the interactions between late-type stars with an outer convection zone and close-in planets, i.e., with an orbital semimajor axis smaller than approximately 0.15 AU. I shall review the roles of tides and magnetic fields considering some key observations and discussing theoretical scenarios for their interpretation with an emphasis on open questions.
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Papers by Antonino Lanza