CONICET | Buscador de Institutos y Recursos Humanos

Double, or binary, stars are of vital importance to astronomy because visual or interferometric observations of the system permit one to determine the sum of the masses of the components if we also know the stars parallax. If radial velocities are also available, one can independently calculate the distance of the system and the individual masses. A new method, based on semi-definite programming (SDP), calculates the apparent orbit of a binary star using visual/interferometric observations and radial velocities. SDP offers advantages over other methods: the calculated ellipse is unique, it represents a global minimum of the reduction criterion if that criterion is the robust L1 norm, and allows mixing different norms for the visual and for the radial velocity data. SDP is compared with alternative methods such as use of a linear reduction model and use of nonlinear least squares. An orbit for Capella ( Aurigae), based on 169 interferometric observations made between 1919 and 1999 and 221 radial velocities made between 1896 and 1991, is calculated.1 norm, and allows mixing different norms for the visual and for the radial velocity data. SDP is compared with alternative methods such as use of a linear reduction model and use of nonlinear least squares. An orbit for Capella ( Aurigae), based on 169 interferometric observations made between 1919 and 1999 and 221 radial velocities made between 1896 and 1991, is calculated. Aurigae), based on 169 interferometric observations made between 1919 and 1999 and 221 radial velocities made between 1896 and 1991, is calculated.