Spectroscopic study of early-type multiple stellar systems. I. Orbits of spectroscopic binary subsystems

M.E. VERAMENDI; J.F. GONZÁLEZ

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2014 vol. 563 p. 1 - 15

0004-6361

Context. The present knowledge of stellar properties and dynamical structure of early-type multiple stellar systems is insufficient to offer useful statistical constraints for stellar formation models. Aims. To increase the amount of observational information about the characteristics of early-type multiples, we have carried out a spectroscopic monitoring, in order to search for new spectroscopic components and to determine their orbits. Methods. We have observed 30 early-type multiple systems using the 2.15 m telescope and REOSC echelle spectrograph at the Complejo Astronómico El Leoncito (CASLEO) during 10 observing runs between 2008 and 2013. We measured radial velocities by cross-correlations and applied a spectral disentangling method to double-lined systems. We calculated orbital elements for the inner subsystem of each analysed multiple. Results. We obtained orbits of previously catalogued subsystems and we detected new binary and multiple  spectroscopic subsystems. In this first paper we present calculated orbits for six previously catalogued subsystems. Three subsystems had no previously published parameters, while we obtained more accurate orbits for the other three. In one case we found absolute masses and radii for the components by using available photometric data. Conclusions. The long term spectroscopic monitoring of multiple systems is a useful method to investigate the existence of companions in intermediate hierarchical levels, particularly those that could affect the dynamical evolution of close inner binary subsystem.