P. M. Marrese

Evaluating GAIA performances on eclipsing binaries - II. Orbits and stellar parameters for V781 Tau, UV Leo and GK Dra

The orbits and physical parameters of three close, double-lined G0xa0eclipsing binaries have been derived combiningxa0

Asiago eclipsing binaries program - I. V432 Aurigae

H_{rm P}, V_{rm T}, B_{rm T}

High resolution spectroscopy over

photometry from the Hipparcos/Tycho mission with 8480–8740xa0Au2000ground-based spectroscopy. The setup is mimicking the photometric and spectroscopic observations that should be obtained by GAIA. The binaries considered here are all of G0xa0spectral type, but each with its own complications: V781xa0Tau is an overcontact system with components of unequal temperature, UVxa0Leo shows occasional surface spots and GKxa0Dra contains a δ xa0Scuti variable. Such peculiarities will be common among binaries to be discovered byxa0GAIA. We find that the values of masses, radii and temperatures for such stars can be derived with a 1–2%u2000accuracy using the adopted GAIA-like observing mode.

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The orbit and physical parameters of the previously unsolved eclipsing binary V432 Aur, discovered by Hipparcos, have been derived with errors better than 1% from extensive Echelle spectroscopy and B, V photometry. Synthetic spectral analysis of both components has been performed, yielding Teff and log g in close agreement with the orbital solution, a metal- licity (Z/Z� ) = −0.6 and rotational synchronization for both components. Direct comparison on the theoretical L,Teff plane with the Padova evolutionary tracks and isochrones for the masses of the two components (1.22 and 1.08 M� ) provides a perfect match and a 3.75 Gyr age. The more massive and cooler component is approaching the base of the giant branch and displays a probable pulsation activity with an amplitude of ∆V = 0.075 mag and ∆rad.vel. = 1.5 km s −1 . With a Teff = 6080 K it falls to the red of the nearby instability strip populated by δ Sct and γ Dor types of pulsating variables. Orbital modeling reveals a large and bright surface spot on it. The pulsations activity and the large spot(s) suggest the presence of macro-turbulent motions in its atmosphere. They reflect in a line broadening that at cursory inspection could be taken as indication of a rotation faster than synchronization, something obviously odd for an old, expanding star.The orbit and physical parameters of the previously unsolved eclipsing binary V432 Aur, discovered by Hipparcos, have been derived with errors better than 1% from extensive Echelle spectroscopy and B, V photometry. Synthetic spectral analysis of both components has been performed, yielding T_eff and log g in close agreement with the orbital solution, a metallicity [Z/Z_sun]=-0.60 and rotational synchronization for both components. Direct comparison on the theoretical L, T_eff plane with the Padova evolutionary tracks and isochrones for the masses of the two components (1.22 and 1.08 M_sun) provides a perfect match and a 3.75 Gyr age. The more massive and cooler component is approaching the base of the giant branch and displays a probable pulsation activity with an amplitude of Delta V = 0.075 mag and Delta rad.vel. = 1.5 km/sec. With a T_eff = 6080 K it falls to the red of the nearby instability strip populated by delta Sct and gamma Dor types of pulsating variables. Orbital modeling reveals a large and bright surface spot on it. The pulsations activity and the large spot(s) suggest the presence of macro-turbulent motions in its atmosphere. They reflect in a line broadening that at cursory inspection could be taken as indication of a rotation faster than synchronization, something obviously odd for an old, expanding star.

8500-8750 Å for GAIA - IV. Extending the cool MK stars sample

A library of high resolution spectra of MK standard and reference stars, observed in support to the GAIA mission, is presented. The aim of this paper is to integrate the MK mapping of Paper I of this series as well as to consider stars over a wider range of metallicities. Radial velocities are measured for all the target stars.

Evaluating Gaia performances on eclipsing binaries - IV. Orbits and stellar parameters for SV Cam, BS Dra and HP Dra

This is the fourth in a series of papers that aim both to provide reasonable orbits for a number of eclipsing binaries and to evaluate the expected performance of Gaia of these objects and the accuracy that is achievable in the determination of such fundamental stellar parameters as mass and radius. In this paper, we attempt to derive the orbits and physical parameters for three eclipsing binaries in the mid-F to mid-G spectral range. As for previous papers, only the Hp, Vt, Bt photometry from the Hipparcos/Tycho mission and ground-based radial velocities from spectroscopy in the region 8480-8740 A are used in the analyses. These data sets simulate the photometric and spectroscopic data that are expected to be obtained by Gaia, the approved ESA Cornerstone mission to be launched in 2011. The systems targeted in this paper are SV Cam, BS Dra and HP Dra. SV Cam and BS Dra have been studied previously, allowing comparisons of the derived parameters with those from full scale and devoted ground-based investigations. HP Dra has no published orbital solution. SV Cam has a beta Lyrae type light curve and the others have Algol-like light curves. SV Cam has the complication of light curve anomalies, usually attributed to spots; BS Dra has non-solar metallicity, and HP Dra appears to have a small eccentricity and a sizeable time derivative in the argument of the periastron. Thus all three provide interesting and different test cases.

Evaluating GAIA performances on eclipsing binaries. III. Orbits and stellar parameters for UW LMi, V432 Aur and CN Lyn

The orbits and physical parameters of three detached F and G-type eclipsing binaries have been derived combining Hipparcosxa0 H P photometry with 8480–8740xa0Au2000ground-based spectroscopy, simulating the photometricxa0+xa0spectroscopic observations that thexa0GAIA mission will obtain. Tychoxa0 B T andxa0 V T light curves are too noisy to be modeled for the three targets, and only mean Tycho colors are retained to constrain the temperature. No previous combined photometric+spectroscopic solution exists in the literature for any of the three targets. Quite remarkably, CNxa0Lyn turned out to be an equal-massesxa0F5 triple system. Distances from the orbital solutions agree within the astrometric error with the Hipparcos parallaxes.