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arXiv 1606.04154astro-ph.SR
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双周期变量HD 170582的低、高阶段多普勒断层成像

Doppler tomography of the Double Periodic Variable HD 170582 at low and high stage

R. E. Mennickent, S. Zharikov, M. Cabezas, G. Djurašević

摘要:

HD 170582是一颗双周期变星(Double Periodic Variable,DPV)型的相互作用双星,其周期为16.87天,光度周期为587天。Mennickent等人(2015)最近研究了它,他们发现了一颗稍微进化的B型恒星,周围环绕着一个发光的吸积盘,由一颗充满罗氏瓣的A型巨星提供。在这里,我们扩展他们的分析,提出新的光谱数据和研究的巴耳末发射线。我们发现轨道调制的双峰Halpha和Hbeta发射,其强度也在长期变化。此外,发射线的多普勒地图显示在第1和第4速度象限的增强线发射的网站,第一个与光变曲线分析检测到的明亮区域之一的位置一致。我们发现在高和低阶段的长周期的多普勒地图之间的差异,证据表明,在高状态下的流盘的影响区域,可能反映了更大的质量传递速率的发射是光学厚。我们将系统参数与合成二进制进化轨迹网格进行比较,并找到最佳拟合模型。该体系为半分离体系,处于保守的Case-B传质阶段,年龄为7.68E7年,传质速率为1.6E-6 Msun/年。对于5个研究得很好的DPV,盘光度与原始质量成比例,并且远大于理论吸积光度。

英文摘要:

HD170582 is an interacting binary of the Double Periodic Variable (DPV) type, showing ellipsoidal variability with a period of 16.87 days along with a long photometric cycle of 587 days. It was recently studied by Mennickent et al. (2015), who found a slightly evolved B-type star surrounded by a luminous accretion disc fed by a Roche-lobe overflowing A-type giant. Here we extend their analysis presenting new spectroscopic data and studying the Balmer emission lines. We find orbitally modulated double-peak Halpha and Hbeta emissions whose strength also vary in the long-term. In addition, Doppler maps of the emission lines reveal sites of enhanced line emission in the 1st and 4th velocity quadrants, the first one consistent with the position of one of the bright zones detected by the light curve analysis. We find a difference between Doppler maps at high and low stage of the long cycle; evidence that the emission is optically thicker at high state in the stream-disc impact region, possibly reflecting a larger mass transfer rate. We compare the system parameters with a grid of synthetic binary evolutionary tracks and find the best fitting model. The system is found to be semi-detached, in a conservative Case-B mass transfer stage, with age 7.68E7 yr and mass transfer rate 1.6E-6 Msun/yr. For 5 well-studied DPVs, the disc luminosity scales with the primary mass and is much larger than the theoretical accretion luminosity.

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