BVRJK photometry and a spectroscopic study of the Algol short-period binary VV Ursae Majoris.
LAZARO C., AREVALO M.J., MARTINEZ-PAIS I.G. and DOMINGUEZ R.M.
Abstract (from CDS):
We present the first light curves in the infrared J and K filters of VV UMa and analyze them, together with a new set of BVR light curves obtained in different runs from 1997 to 2000. Based on the spectra of VV UMa and standard stars in the region 8440-8870 Å, we classify the primary component of the binary as a type A1.5-2 V star. Evidence of periodic small-amplitude variations in the brightness of the system is found and is more clear during the secondary eclipse orbital phases. A periodicity of about 0.51 hr is in good agreement with a previous finding based on Strömgren photometry, pointing to a real origin in the system, presumably on low-amplitude pulsations of the primary star. The analysis of the BVRJK light curves, using a code based on ATLAS model atmospheres, yields new orbital and stellar parameters. We derive effective temperatures Teff=9250±150 K and Teff=5600±100 K for the primary and secondary star, respectively. We challenge the current view that VV UMa is a system with unusually low mass components for their spectral type, and an alternative solution is proposed, allowing masses of the stars in the expected range for their spectral types that are in reasonable agreement with the available photometric and spectroscopic data. From the visual-infrared photometry we find no evidence of a significant infrared excess in the system, deriving an interstellar reddening E(B-V)≤0.10.