FU Ori type variables: from spotted stars to spotted disks
Abstract
Brief review and analysis of 40 yrs of photometric observations of FU Ori type variables (FUors) was made. Quasiperiodic variations in FUor light curves have two components: long-term (∼ 1600 days, "long periods") and short-term variations (∼ 20 - 500 days, "short periods"). Long periods are stable, short ones change with time. Gradual increase of short period values and amplitudes (5-25 and 10 times in 10-20 yrs, respectively) is discussed. Spotted disk hypothesis is proposed to explain short periods. The hypothesis allows to account for observed features of short periods and to derive important quantitative estimates. Estimation of α-parameter (3×10^-3 , first time made observational estimation of the parameter) and estimation of changes of V1057 Cyg radiative disk dimension (from ∼ 20R⊙ in 1990 to ∼ 170R⊙ in 2010) were obtained. Change of temperature contrasts for disk sports was estimated ("late" spots have by order of magnitude larger contrast in comparison with "early" spots).
- Publication:
-
A.A. Boyarchuk Memorial Conference
- Pub Date:
- May 2018
- DOI:
- 10.26087/INASAN.2018.1.1.016
- Bibcode:
- 2018abmc.conf...88I