Analysis of three close eclipsing binary systems: BP Velorum, V392 Carinae and V752 Centauri
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
This thesis reports photometric and spectroscopic studies of three close binary systems; BP Velorum, V392 Carinae and V752 Centauri. BP Velorum, a W UMa-type binary, was observed photometrically in February 2007. The light curves in four filters were fitted simultaneously with a model generated in the eclipsing binary modeling software package PHOEBE. The best model was one with a cool star spot on the secondary larger component. The light curves showed additional cycle-to-cycle variations near the times of maximum light which may indicate the presence of star spots that vary in strength and/or location on a time scale comparable with the orbital period, (P = 0.265 d). The system was confirmed to belong to the W-type subgroup of W UMa binaries for which the deeper primary minimum is due to an occultation. V392 Carinae, a detached binary with an orbital period of 3.147 d, was observed photometrically by Michael Snowden in 1997. These observations were reduced and combined with the published light curve from Debernardi and North (2001). High resolution spectroscopic images were taken using the University of Canterbury's HERCULES spectrograph. The radial velocities measured from these observations were combined with velocities from Debernardi and North (2001). The radial velocity and light curves were fit simultaneously, confirming that V392 Car is a detached system of two main sequence A stars with a mass-ratio of 0.95. The derived systematic velocity is consistent with V392 Car being a member of the open cluster NGC 2516. The W UMa-type binary V752 Centauri was observed photometrically and spectroscopically during 2007. The high resolution spectra displayed weak sharp lined features superimposed over the strong broad lined spectrum expected from the 0.370 d contact binary. Fourier methods were used to separate the broad and sharp spectral features and radial velocities for each were measured by cross-correlation. A fit to the photometry and radial velocities for the contact binary implied a system of two late F stars with a mass-ratio of 3.38 in an over-contact configuration. The derived systematic velocity (−13.8km/s), has changed significantly from the 1972 value (29.2km/s). The third (sharp lined) component's radial velocities were measured and found to have a period of 5.147 d, semi-amplitude of 43.4km/s and systematic velocity of −7.3km/s. The likely configuration of the entire system is that of a contact binary in a long period orbit about a lower mass detached binary. V752 Cen is thus a triple lined spectroscopic quadruple.