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arXiv 1511.03450astro-ph.SR
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IRAS22272 +5435的光谱变异性

Spectroscopic variability of IRAS22272+5435

L. Začs, F. Musaev, B. Kaminsky, Y. Pavlenko, A. Grankina, J. Sperauskas, B. J. Hrivnak

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23 pages, 14 figures, 7 tables, accepted for publication in ApJ
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摘要：

观测到明亮的原行星状星云IRAS 22272 +5435（HD 235858）在光波段的高分辨率光谱时间序列，同时监测其径向速度和$BVR_C$星等。已知该物体由于周期为132天的脉动而在光、颜色和速度上发生变化。光和颜色的变化伴随着光谱特征的显着变化，其中大部分被确定为含碳分子的线条。观测结果表明，在光极小值附近，$C_2$天鹅系和CN红系的谱线较强。用新的自洽大气模型计算了中心星的光球光谱。在$C_2$天鹅系统和CN红系统线中观察到的强度变化被发现比预期的要大得多，如果仅仅是由于脉动星大气中的温度变化。此外，分子谱线相对于光球速度发生蓝移。强分子特征的形成部位似乎是由脉动触发的冷流出。原子谱线的变化似乎主要是由于脉动周期中有效温度的变化。强原子谱线的轮廓是分裂的，其中一些在一周左右的时间尺度内是可变的，可能是因为外层大气中的激波。

英文摘要：

A time series of high-resolution spectra was observed in the optical wavelength region for the bright proto-planetary nebula IRAS22272+5435 (HD235858), along with a simultaneous monitoring of its radial velocity and $BVR_C$ magnitudes. The object is known to vary in light, color, and velocity due to pulsation with a period of 132 days. The light and color variations are accompanied by significant changes in spectral features, most of which are identified as lines of carbon-bearing molecules. According to the observations, the $C_2$ Swan system and CN Red system lines are stronger near the light minimum. A photospheric spectrum of the central star was calculated using new self-consistent atmospheric models. The observed intensity variations in the $C_2$ Swan system and CN Red system lines were found to be much larger than expected if due solely to the temperature variation in the atmosphere of the pulsating star. In addition, the molecular lines are blueshifted relative to the photospheric velocity. The site of formation of the strong molecular features appears to be a cool outflow triggered by the pulsation. The variability in atomic lines seems to be mostly due variations of the effective temperature during the pulsation cycle. The profiles of strong atomic lines are split, and some of them are variable in a time scale of a week or so, probably because of shock waves in the outer atmosphere.

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