Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the luminous blue variable R71
Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the luminous blue variable R71
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发光蓝色变量 R71 的 S Doradus 爆发期间的光谱和光度振荡包络变化
DOI：
10.1051/0004-6361/201731829
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发表时间：
2017
影响因子：
6.5
通讯作者：
O. Stahl
中科院分区：
文献类型：
--
作者：
A. Mehner;D. Baade;J. Groh;T. Rivinius;F. Hambsch;E. Bartlett;D. Asmus;C. Agliozzo;T. Szeifert;O. Stahl
为了更好地理解LBV现象，我们分析了R71的多历元、多波长光谱和光度。利用辐射传输代码CMFGEN分析爆发前的光谱，确定恒星的基本参数。在静止状态下，R71的有效温度为$T_\ mathm {eff} = 15,500~K$，光度为log$(L_*/L_{\odot})$ = 5.78，因此它是一个经典的LBV，但它的光度较低。我们确定它的质量损失率为$4.0 \乘以10^{-6}~M_{\odot}~$yr$^{-1}$。我们给出了R71爆发期间从近紫外到中红外的光谱能量分布。中红外观测表明，我们正在见证尘埃的形成和颗粒的演化。在当前爆发期间，观测到恒星光曲线的半规则振荡变异性。吸收线在两倍长度的时间尺度上产生第二个蓝色分量。变率可能由P ~ 425/ 850d的一个（准）周期分量和附加变化叠加而成。在当前的剑鱼座S爆发期间，R71在造父变星不稳定带的高亮度延伸处占据了HR图中的一个区域，并表现出与RV Tau变量相似的不规则变化。由于核心的演化，lbv不会通过造父变星的不稳定带，但它们会形成相当冷的、低质量的、扩展的大气，在这种大气中可能会发生对流不稳定。与RV Tau变量的情况一样，具有明显规则周期的双吸收谱线的出现可能是由于大气中的冲击，周期加倍可以解释光度和光谱周期长度的2因素。
To better understand the LBV phenomenon, we analyze multi-epoch and multi-wavelength spectra and photometry of R71. Pre-outburst spectra are analyzed with the radiative transfer code CMFGEN to determine the star's fundamental stellar parameters. During quiescence, R71 has an effective temperature of $T_\mathrm{eff} = 15\,500~K$ and a luminosity of log$(L_*/L_{\odot})$ = 5.78 and is thus a classical LBV, but at the lower luminosity end of this group. We determine its mass-loss rate to $4.0 \times 10^{-6}~M_{\odot}~$yr$^{-1}$. We present R71's spectral energy distribution from the near-ultraviolet to the mid-infrared during its present outburst. Mid-infrared observations suggest that we are witnessing dust formation and grain evolution. Semi-regular oscillatory variability in the star's light curve is observed during the current outburst. Absorption lines develop a second blue component on a timescale twice that length. The variability may consist of one (quasi-)periodic component with P ~ 425/850 d with additional variations superimposed. During its current S Doradus outburst, R71 occupies a region in the HR diagram at the high-luminosity extension of the Cepheid instability strip and exhibits similar irregular variations as RV Tau variables. LBVs do not pass the Cepheid instability strip because of core evolution, but they develop comparable cool, low-mass, extended atmospheres in which convective instabilities may occur. As in the case of RV Tau variables, the occurrence of double absorption lines with an apparent regular cycle may be due to shocks within the atmosphere and period doubling may explain the factor of two in the lengths of the photometric and spectroscopic cycles.
不均匀热星风的质量损失 III 加速、聚集的双组分介质中线辐射传输的有效不透明形式主义，以及理论和诊断的第一个结果
DOI：
10.1051/0004-6361/201423570
发表时间：
2014
期刊：
arXiv: Solar and Stellar Astrophysics
影响因子：
--
作者：
Sundqvist J.O;Puls. J;Owocki S.P.
通讯作者：
Owocki S.P.