Photometric study of the W UMa eclipsing binaries VW LMi and BX Dra

Abstract

New ephemeris and the absolute parameters—masses, radii and luminosities—of the contact systems VW LMi and BX Dra have been obtained, by means of the analysis of the minima data available in the literature (for the determination of the ephemeris) and combining the previously published spectroscopic information and the results of the Wilson-Devinney method using photometric data (for the determination of the absolute parameters). The VW LMi O‑C analysis confirms the multiplicity of the system detected previously from the spectroscopic data. Masses of the VW LMi contact system primary and secondary components are 1.67 ± 0.02M_⊙ and 0.70 ± 0.02M_⊙, respectively. The corresponding radii are 1.709 ± 0.007R_⊙ and 1.208 ± 0.006R_⊙, respectively. For the BX Dra contact system the masses are 2.19 ± 0.13M_⊙ and 0.63 ± 0.06M_⊙, and the radii, 2.13 ± 0.04R_⊙ and 1.26 ± 0.03R_⊙, for the primary and secondary, respectively. In both cases, the estimated luminosities seem to be slightly greater that the values derived from the Hipparcos distances.