THE FINAL HELIUM FLASH OBJECT SAKURAI - PHOTOMETRIC BEHAVIOR AND PHYSICAL CHARACTERISTICS

Six-color broadband photometry of Sakurai's Object, a star that underw ent a final helium flash in late 1994, has been carried out since 1996 February. The light curves show that Sakurai's Object is continuously cooling while it slowly expands and slightly increases its luminosity . The distance is estimated to be 8 kpc, the interstellar extinction E B-V=0.53, and the luminosity in early 1997 is 10 000 L.. The high lumi nosity indicates that the white dwarf is quite massive. With the assum ption of a slightly accelerated photospheric expansion a realistic des cription of the outburst light curve is achieved, Superimposed on the gradual brightness changes are variations with amplitudes of up to 0.1 mag and cycle lengths of 63, 23, 14, and 8 days. In spite of the fact that no persistent periodicities could be detected, pulsational studi es show that such cyclic changes can be used to constrain stellar para meters such as mass, luminosity, and chemical abundances. (C) 1997 Ame rican Astronomical Society.