Young stars in gas-dust disks. II. Vega (α Lyr) and β Pic

Abstract

Observational data for Vega, α Lyr in the 325-1080 nm range from various years are studied using material stored at the Pulkovo Spectrophotometric Data Base (PSDB). It is shown that the spectrophotometric temperature of the star was lower than the effective temperature according to data from all the observational seasons. Possible reasons for this are examined: light scattering by small particles in the ultraviolet and reflection by large particles at longer wavelengths. A difference of 0^m.01-0^m.02 in the quasimonochromatic magnitudes of the star is obtained for observations in different seasons. This difference may related to a large-scale inhomogeneity in the distribution of dust and gas in the disk. Photometric data for the star β Pic in the Hipparcos catalog reveal periodic variations in the Vt magnitude with a period of 4.46 d and an amplitude of 0^m.0085. Three assumptions are made to explain this result: pulsations in the star's photosphere, a planet at a distance of ~0.1 a.u., and a region with an elevated density of particles in the circumstellar disk that periodically eclipses the star as it undergoes Kepler rotation. These assumptions require further confirmation.