Extreme Ultraviolet Explorer Photometry of RS Canum Venaticorum Systems: Four Flaring Megaseconds

摘要: We present an analysis of 12.2 Ms Extreme Ultraviolet Explorer (EUVE) photometry 16 RS CVn systems (including four flaring megaseconds). Our study attempts a systematic categorization stellar coronal emission in binary systems. The temporal resolution the EUVE satellite and opportunity for long observations enables us to separately quiescent states Thirty 31 are statistically variable. examine light curves, characterizing both phase-dependent variations large- small-scale flaring. There is evidence stochastic variability on one short-period (Porb 0.5Porb thus cannot originate from compact regions close surfaces. Many flares have unusual flare morphologies, with rise times comparable or greater than decay time, plateaus. In addition, eight phases that fit better by broken power law single law. second different correlated times. This observed connection points potential importance change rate as means examining physical processes operating during flare. distribution orbital onsets V711 Tau (HR 1099), best-studied our sample, consistent Poisson random time. two partially eclipsing (CF Tuc ER Vul), we find no eclipse curve, indicating region large compared radius. parameterize energies law, finding cut-off energy ≈1033 ergs slope -0.6. Flare increases duration E∝Δt1.42, confirming long-duration nature high-energy integrated luminosity depends Lflare∝L1.05quiescent. frequencies range 0.1 day-1 1.5 day-1. For not affected dead spot Deep Survey detector, 40% time was spent state, "normal" state coronae these note presence quasi-periodicity photometric data order 1 day, which corrected standard reduction software.