Young stars in gas-dust disks. I. Fomalhaut |
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Authors: | E V Ruban A A Arkharov |
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Institution: | 1. Main (Pulkovo) Astronomical Observatory, Russian Academy of Sciences, Pulkovo, Russia
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Abstract: | This is a single-factor analysis of the variance of the average quasimonochromatic magnitudes of Fomalhaut, α PsA, in the
325-1080 nm spectral range for different observation seasons collected in the Pulkovo Spectrophotometric Data Base (PSDB).
The overall variance of the data combined over several seasons is decomposed into components characterizing the randomness
and variability factors separately. The influence of the variability factor on the variance of the average magnitudes is found
to be significant with a confidence coefficient exceeding 95%. The estimated amplitude of the variability is 0m.02-0m.03. It is proposed that the main causes of the variability are photospheric pulsations (changes in the temperature by ~40 K
and in the radius by ~0.5%) and variations in the scattering of radiation by dust in the circumstellar disk owing to the large
scale inhomogeneity of the disk. Data from the Hipparcos catalog indicate a variability of the star in the Vt band with an amplitude of ~0m.017 and a period of 20.6 days. It is suggested that the disk surrounding the star contains a region with an elevated concentration
of particles which periodically eclipses the star as it undergoes Kepler rotation. Another explanation is also proposed: transit
of an unknown planet across the star’s disk. The existence of a planet at a distance of ~0.2 a.u. will require further confirmation. |
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