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摘要
Statistically analyzing Johnson UBVR observations of V1285 Aql during the three observing seasons, both activity level and behavior of the star are discussed in respect to obtained results. We also discuss the out-of-flare variation due to rotational modulation. Eighty-three flares were detected in the U-band observations of season 2006. First, depending on statistical analyses using the independent samples t-test, the flares were divided into two classes as the fast and the slow flares. According to the results of the test, there is a difference of about 73 s between the flare-equivalent durations of slow and fast flares. The difference should be the difference mentioned in the theoretical models. Second, using the one-phase exponential association function, the distribution of the flare-equivalent durations versus the flare total durations was modeled. Analyzing the model, some parameters such as plateau, half-life values, mean average of the flare-equivalent durations, maximum flare rise, and total duration times are derived. The plateau value, which is an indicator of the saturation level of white-light flares, was derived as 2.421 +/- 0.058 s in this model, while half-life is computed as 201 s. Analyses showed that observed maximum value of flare total duration is 4641 s, while observed maximum flare rise time is 1817 s. According to these results, although computed energies of the flares occurring on the surface of V1285 Aql are generally lower than those of other stars, the length of its flaring loop can be higher than those of more active stars. Moreover, the out-of-flare variation activity was analyzed using three methods of time-series analysis, and a sinusoidal-like variation with a period of 3.1265 days was found for out-of-flare rotational modulation for the first time in literature. Considering the variations of V - R. color, these variations must be because of some dark spot(s) on the surface of that star. In addition, using the ephemeris obtained from time-series analyses, the distribution of the flares was examined. The phase of maximum mean flare occurrence rates and the phase of rotational modulation were compared to investigate whether there is any longitudinal relation between stellar flares and spots. The analyses show that there is a tendency of longitudinal relation between stellar flares and spot(s). Finally, it was tested whether slow flares are the fast flares occurring on the opposite side of the stars according to the direction of the observers, as mentioned in the hypothesis developed by Gurzadian. The flare occurrence rates reveal that both slow and fast flares can occur in any rotational phases.
- 出版日期2011-6
