August 7-10, 2017


Beta Lyrae: The binary and its BRITE observations in 2016

Slavek Rucinski (University of Toronto)

Beta Lyrae is an eclipsing binary with the orbital period of 12.9 days, consisting of a B6-8II Roche-lobe filling component and an invisible (possibly collapsed) component with a mass estimated at 13 solar masses. A prominent and easily studied period variation has been followed since the late 1700's leading to a firm interpretation that the invisible component is fed by matter constantly flowing from the visible component. In addition to its eclipsing variability the binary shows a rich range of accretion-powered phenomena in practically all accessible wavelengths. The goal of BRITE observations was to obtain an un-interrupted light curve over several eclipse cycles to study previously noted light-curve instabilities which may reach up to 0.01 mag. The instabilities have so far been uncharacterized with a possibility that they simply resulted from poor photometry over long periods of time. The talk will describe the binary and the unexpected complications introduced by a technical problem with data collection by the otherwise excellent satellite BTr. A hard to diagnose CTI problem caused a fractional loss in the CCD signal. After the data were processed by Andrzej Pigulski's de-correlation pipeline, an attempt has been made to estimate the photometric loss utilizing a temporal overlap of the BTr data with the UBr observations. The BTr light curve has been corrected assuming a constant signal loss over a CCD patch where the star was imagined; these data have been shared with the co-PI's. Preliminary results on the section of the light curve is subject to the most frequent changes will be presented. An attempt will be made to characterize the temporal content of the non-eclipsing, light-curve variability.

Mode of presentation need to be confirmed by the SOC