Period decrease in three SuperWASP eclipsing binary candidates near the short-period limit

Abstract

SuperWASP light curves for 53 W UMa-type eclipsing binary (EB) candidates, identified in previous work as being close to the contact binary short-period limit, were studied for evidence of period change. The orbital periods of most of the stars were confirmed, and period decrease, significant at more than 5σ, was observed in three objects: 1SWASP J174310.98+432709.6 (−0.055 ± 0.003 s yr −1 ), 1SWASP J133105.91+121538.0 (−0.075 ± 0.013 s yr −1 ) and 1SWASP J234401.81−212229.1 (−0.313 ± 0.019 s yr −1 ). The magnitudes of the observed period changes cannot be explained by magnetic braking or gravitational radiation effects, and are most likely primarily due to unstable mass transfer from primary to secondary components, possibly accompanied by unstable mass and angular momentum loss from the systems. If these period decreases persist, the systems could merge on a relatively short timescale.

The doubly eclipsing quintuple low-mass star system 1SWASP J093010.78+533859.5

“…The eclipsing source's apparently significant period change, associated with an erratic O−C diagram, had been rejected initially as the result of contamination by a nearby star (Lohr et al 2012), but in Lohr et al (2013b) a fuller explanation was pursued. Prior to analysis, the data for J093010 and J093012 were combined to maximize the available observations.…”

Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

“…The archive contains high-cadence photometric light curves for bright sources (V ∼ 8-15 mag) over almost the whole sky, stretching back to 2004 in many cases, and so should be capable of filling in gaps or extending the coverage of O−C diagrams for many of these systems. We have previously observed and measured period changes in short-period main sequence eclipsing binary candidates using SuperWASP data (Lohr et al 2012(Lohr et al , 2013; here, we develop our analytical method to improve the precision and robustness of its period change measurements, and to search for variations in light curve amplitude as well. It is hoped that the results may shed light on future investigations of this intriguing group of eclipsing binary systems.…”

Parameters of two low-mass contact eclipsing binaries near the short-period limit

“…Both were initially identified in Norton et al (2011); the period of J150822 was revised upwards to 22 469.2 s in Lohr et al (2012) and therefore it did not appear in Lohr et al (2013). We report system and component parameters obtained for these EBs by simultaneous modelling of their SuperWASP light curves and radial velocities.…”

“…Fifty-three candidates were found, 48 of which were new discoveries at the time. A subsequent search of these candidate EBs for evidence of period change (Lohr et al 2012) corrected the periods of nine EBs to values slightly higher than 20 000 s, but still with <22 600 s (∼0.2616 d). A more rigorous search of the SuperWASP archive (Lohr et al 2013) then detected 143 candidate EBs with periods <20 000 s, including 97 new discoveries since the publication of Norton et al (2011), and measured significant period changes in 74 candidates.…”