Publications of the Astronomical Society of the Pacific
108: 338-343, 1996 April

             Photometric Analysis of the Contact Binary BF Pavonis

             J. F. GONZALEZ, E. LAPASSET, M. GOMEZ, AND J. AHUMADA

    Observatorio Astronomico, Universidad Nacional de Cordoba, Laprida 854,
                            5000 Cordoba, Argentina
     Electronic mail: (gonzalez, lapasset, mergom, ahumuda)@uncbob.edu.ar

     ABSTRACT.  We present UBV photoelectric observations of the W UMa star
     BF Pav obtained between 1987 and 1993.  A time-of-minimum study allows
     detection of a likely period increase of about 0.015 s/yr.  The
     Wilson-Devinney code is employed to simultaneously model the B and V
     light curves for several fixed values of the mass ratio q.  From the
     quality-of-fit of the different solutions an approximate value of
     q=1.4+/-0.2 is derived.  Absolute values of masses, dimensions, and
     luminosities are estimated by means of standard mass-luminosity
     relations for main-sequence stars.  The detected period variation
     determines a lower limit of 5 x 10^-7 Msun/yr for the rate of mass
     transfer from the less-massive to the more-massive component.  We
     speculate that BF Pav has recently become in contact and is now in a
     rapid phase of mass transfer.