Spectroscopic-photometric analysis of the binary system V4089 Sagitarii

VERAMENDI, M. E.; GONZALEZ, J. F.

Margarita, Venezuela

Congreso; XII Reunión Latioamericana de la IAU; 2007

Unión Astronómica Internacional

We present an observational analysis of the eclipsing     double-lined spectroscopic binary HR7422=V4089 Sgr. Nineteen     spectra were obtained with the 2.15-m telescope and the bench     echelle spectrograph EBASIM of the CASLEO, while photometric     observations in the Johnson V band were carried out with the 61     cm telescope at CASLEO. We measured radial velocities to a precision     of 0.45 km/s for both stellar components using the method of separation     of composite spectra by González \& Levato (2006, A&A 448, 283).     From light and radial velocity curves we derived orbital and physical     parameters for the system using the Wilson & Devinney code. With this     aim, our light curve was complemented with the photometry in the V band     of the Geneva system published by North et al. (1997, A&A 324, 137).     We obtained masses and radii to a precision of 0.45% and  0.9%, respectively.    The system V4089 Sgr is very useful to test stellar models due to the great     difference between the components. The comparison with theoretical stellar     models of Lejeune & Schaerer (2001, A&A 366, 538) suggest an age of     log(age) =8.695 +- 0.007 yr. Since the primary is close to the TAMS, we     used this system to compare the predictions of standard and overshooting models.