Effect of hot jupiters on the variability of stellar radiation

Abstract

The effect of hot jupiters on the variability of light from 14 bright stars with planets that are listed in the Pulkovo Spectrophotometric Catalog (PSC) and the Hipparcos photometric catalog is studied. The spectral range 320-1080 nm and the Vt and Bt photometric magnitudes are examined. The photometric observations reveal microvariability of the star τBoo in the Vt and Bt bands with amplitudes of ~0m.018 and ~0m.020 and periods of ~3.4 d and ~3.2 d, respectively. The coincidence of the periods of the variability with the orbital period of τBoo b around the star indicates that the microvariability is associated with the orbit of the planet. Microvariability of the star 51 Peg is also observed in the Bt band with an amplitude of 0m.023, essentially the same as the magnitude of the decrease in the brightness as the planet crosses the star’s disk, but with a period of 11.6 d, a factor of 3 longer than the planet’s orbital period of 4.2 d. Apparently the planet 51 Peg b crosses the star’s disk once in three orbital cycles. This could indicate the presence of an additional body (another planet?) in the star-planet system that perturbs the planet’s orbit. According to spectrophotometric observations, no effect caused by even the very hottest jupiters was found.