Ennio Poretti

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Oscillations of the Sun have been used to understand its interior structure. The extension of similar studies to more distant stars has raised many difficulties despite the strong efforts of the international community over the past decades. The CoRoT (Convection Rotation and Planetary Transits) satellite, launched in December 2006, has now measured(More)
The OGLE database is revisited to investigate in more detail the properties of the Fourier parameters. Methodological improvements led us to identify a clear separation among High–Amplitude δ Scuti (HADS), RRc and RRab stars. The bimodal distribution of the R21parameter in HADS stars is explained as a contamination effect from RRc stars: there is evidence(More)
The results obtained by means of the photometric approach to the study of δ Sct stars are extensively discussed. The different frequency contents of the three best candidates for asteroseismological studies (FG Vir, 4 CVn and XX Pyx) are presented and compared; the importance of the amplitude variations and of the combination terms is emphasized. The(More)
We lack a reliable scenario for the formation and evolution of stars and their planetary systems, involving key factors such as magnetic fields and turbulence. We present the case for a mission concept that will clarify these problems and give us a global view of the evolution of combined star and planetary systems. This will be achieved by simultaneously(More)
We report a multisite photometric campaign for the β Cephei star 12 Lacertae. 750 hours of high-quality differential photoelectric Strömgren, Johnson and Geneva timeseries photometry were obtained with 9 telescopes during 190 nights. Our frequency analysis results in the detection of 23 sinusoidal signals in the light curves. Eleven of those correspond to(More)
The bright variable star θ Tauwas monitored with the star camera on the Wide–Field Infrared Explorer satellite. Twelve independent frequencies were detected down to the 0.5 mmag amplitude level. Their reality was investigated by searching for them using two different algorithms and by some internal checks: both procedures strengthened our confidence in the(More)
We present multi-site photometric observations of the F0 IV star HR 2740≡QW Pup which reveal it to be a γ Dor type variable pulsating with four frequencies: 1.0434, 0.9951, 1.1088, 0.9019 d. These data were obtained at the European Southern Observatory and South African Astronomical Observatory over a time baseline spanning from 1997 January 14 to 1997(More)
II Peg is an ideal target to study stellar activity and flares, since intense and long lasting flares have been frequently detected from this system at all wavelengths. We report here about a BeppoSAX observation of II Peg. We followed the system for ∼ 19 hours on December 5 and 6 1997 with BeppoSAX and the X-ray light curve resembles the typical behavior(More)
Context. Searching for planets in open clusters allows us to study the effects of dynamical environment on planet formation and evolution. Aims. Considering the strong dependence of planet frequency on stellar metallicity, we studied the metal rich old open cluster NGC 6791 and searched for close-in planets using the transit technique. Methods. A ten-night(More)