相互作用双星DQ Velorum的长期变化和演化阶段的探索
Exploring the long-term variability and evolutionary stage of the interacting binary DQ Velorum
摘要：
为了进一步理解双周期变量（DPV）现象，我们分析了DPV系统DQ Velorum在其长周期的大部分时间内的一系列光谱。此外，我们调查DQ Vel的演化历史，使用理论演化模型，以获得最佳的代表性，目前观测到的恒星和轨道参数的二进制。我们通过理论演化模型研究了DQ Vel的演化，估算了其年龄和传质速率，并与其孪生子V393 Scorpii进行了比较。供体减去光谱覆盖约60%的长期周期，使我们能够调查的增益星加上光盘的时间调制光谱变化。我们比较观察到的恒星系统的参数与保守和非保守的演化制度下计算的理论演化轨道的网格。我们发现，在施主扣除谱中，巴耳末线和氦线的EW随长周期的变化而变化。我们观察到的所有分析的光谱特征在最低的长期周期，这可能是一个额外的线发射在最大的长期变化的EW的加强。在二次日食获得的差异光谱支持这种情况。我们已经发现，一个非保守的演化模型是一个更好的代表目前所观察到的系统的属性。最佳进化模型表明，DQ Vel的年龄为7.40 x 10^{7}年，在经历了一次传质爆发事件后，目前处于低传质速率（-9.8x10 ^{-9} Msun/yr）阶段。比较DQ Vel和V393 Sco的演化阶段，我们观察到前者是一个较老的系统，具有较低的传质速率。这也许可以解释在它们的吸积盘的物理参数中观察到的差异。
英文摘要：
To progress in the comprehension of the double periodic variable (DPV) phenomenon, we analyse a series of optical spectra of the DPV system DQ Velorum during much of its long-term cycle. In addition, we investigate the evolutionary history of DQ Vel using theoretical evolutionary models to obtain the best representation for the current observed stellar and orbital parameters of the binary. We investigate the evolution of DQ Vel through theoretical evolutionary models to estimate the age and the mass transfer rate which are compared with those of its twin V393 Scorpii. Donor subtracted spectra covering around 60% of the long-term cycle, allow us to investigate time-modulated spectral variations of the gainer star plus the disc. We compare the observed stellar parameters of the system with a grid of theoretical evolutionary tracks computed under a conservative and a non-conservative evolution regime. We have found that the EW of Balmer and helium lines in the donor subtracted spectra are modulated with the long-term cycle. We observe a strenghtening in the EWs in all analysed spectral features at the minimum of the long-term cycle which might be related to an extra line emission during the maximum of the long-term variability. Difference spectra obtained at the secondary eclipse support this scenario. We have found that a non-conservative evolutionary model is a better representation for the current observed properties of the system. The best evolutionary model suggests that DQ Vel has an age of 7.40 x 10^{7} yr and is currently in a low mass transfer rate (-9.8x10^{-9} Msun/yr) stage, after a mass transfer burst episode. Comparing the evolutionary stages of DQ Vel and V393 Sco we observed that the former is an older system with a lower mass transfer rate. This might explain the differences observed in the physical parameters of their accretion discs.
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