Light-curve instabilities of Beta Lyrae observed by the BRITE satellites

Abstract

Photometric instabilities of $\beta$ Lyr were observed in 2016 by two red-filter BRITE satellites over more than 10 revolutions of the binary, with $\sim$100-minute sampling. Analysis of the time series shows that flares or fading events take place typically 3 to 5 times per binary orbit. The amplitudes of the disturbances (relative to the mean light curve, in units of the maximum out-of-eclipse light-flux, f.u.) are characterized by a Gaussian distribution with $\sigma =0.0130\pm 0.0004$ f.u. Most of the disturbances appear to be random, with a tendency to remain for one or a few orbital revolutions, sometimes changing from brightening to fading or the reverse. Phases just preceding the center of the deeper eclipse showed the most scatter while phases around secondary eclipse were the quietest. This implies that the invisible companion is the most likely source of the instabilities. Wavelet transform analysis showed domination of the variability scales at phase intervals $0.05-0.3$ (0.65--4 d), with the shorter (longer) scales dominating in numbers (variability power) in this range. The series can be well described as a stochastic Gaussian process with the signal at short timescales showing a slightly stronger correlation than red noise. The signal de-correlation timescale $\tau =(0.068\pm 0.018)$ in phase or $(0.88\pm 0.23)$~d appears to follow the same dependence on the accretor mass as that observed for AGN and QSO masses 5--9 orders of magnitude larger than the $\beta$~Lyr torus-hidden component.

arXiv comment28 pages, 10 figures, accepted by AJ: 3 May 2018

References in corpus (17)

• Are the Variations in Quasar Optical Flux Driven by Thermal Fluctuations?
• Modeling the Time Variability of SDSS Stripe 82 Quasars as a Damped Random Walk
• Quantifying Quasar Variability As Part of a General Approach To Classifying Continuously Varying Sources
• Is Quasar Optical Variability a Damped Random Walk?
• A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
• First Resolved Images of the Eclipsing and Interacting Binary Beta Lyrae
• BRITE-Constellation: nanosatellites for precision photometry of bright stars
• Revisiting Stochastic Variability of AGNs with Structure Functions
• Quasar Optical Variability in the Palomar-QUEST Survey
• Limitations on the recovery of the true AGN variability parameters using Damped Random Walk modeling
• The BRITE Constellation nanosatellite mission: Testing, commissioning and operations
• A Degeneracy in DRW Modelling of AGN Light Curves
• BRITE-Constellation: Data processing and photometry
• On the accretion disc and evolutionary stage of beta Lyrae
• A Method to Measure the Unbiased Decorrelation Timescale of the AGN Variable Signal from Structure Functions
• Geometrical Constraints on the Hot Spot in Beta Lyrae
• Phase-dependent X-ray observations of the beta Lyrae system: No eclipse in the soft band

Cited by in corpus (2)

• A characteristic optical variability timescale in astrophysical accretion disks
• Photometry of Beta Lyrae in 2018 by the BRITE satellites