• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The Astrophysical journal >MODELING THE VARIABLE CHROMOSPHERE OF α ORIONIS
【24h】

MODELING THE VARIABLE CHROMOSPHERE OF α ORIONIS

机译：模拟Orionis的可变染色体

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

A spectral analysis of the prototypical red supergiant star α Ori that is based on near-UV, optical, and near-IR high-dispersion spectra obtained between l992 September and l999 July with the Space Tele- scope Imaging Spectrograph and the Goddard High Resolution Spectrograph on the Hubble Space Telescope, the Utrecht Echelle Spectrograph, and the SoFin Echelle Spectrograph is presented. With detailed non-LTE radiative transfer calculations in spherical geometry, we model the mean conditions in the stellar chromosphere from Ha and the Mg II resonance doublet. The Ha absorption line emerges from an extended chromosphere. Temporal changes of its velocity structure are determined from detailed fits to near-UV Si I lines, and chromospheric expansion velocities around 4 km s~-1 are found in 1992, whereas the chromosphere was collapsing onto the photosphere with a velocity of 5 km s~-1 in 1998- l999. The Ha core depth is correlated over time with weaker depression changes seen in prominent TiO band heads that dominate the optical spectrum. From elaborate spectral synthesis calculations, we isolate unblended metal absorption lines in the near-IR and determine Z,, = 3500 K and log (g) = --0.5 for solar metallicity and 12 ±0.5 km s~-1 for macrobroadening and vsini. Semiempirical fits yield chromospheric temperatures not in excess of 5500 K, but with long-term changes by ~400 K. The model extends over 5000 Ro and requires supersonic microturbulence values ranging to 19 km s --', in strong contrast with the photospheric value of only 2 km s -- 1. We observe Doppler shifts of only 2 km s ~-1 in the scattering cores of many double-peaked near-UV emission lines which correlate with changes in the intensity ratio of their emission components. The red emission components were much stronger in l992, indicating a phase of enhanced chromospheric outflow, for which we determine a spherical mass- loss rate of 6 x l0~-7 Mo yr~-1. We present a discussion of chromospheric pulsation in this massive star. Detailed modeling of the observed Mg II h and k line asymmetry is also presented. We demonstrate that a chromospheric Mn I blend strongly contributes to this puzzling asymmetry.
机译：利用空间望远镜成像光谱仪和戈达德高分辨率光谱仪对9月1999年至1999年7月之间获得的近紫外，光学和近红外高分散光谱进行了原型红色超巨星αOri的光谱分析在哈勃太空望远镜上展示了乌特勒支埃歇尔光谱仪和SoFin埃歇尔光谱仪。通过在球形几何体中进行详细的非LTE辐射传输计算，我们根据Ha和Mg II共振双峰对恒星色球中的平均条件进行建模。 Ha吸收线从扩展的色球中露出。其速度结构的时间变化取决于对近紫外Si I线的详细拟合，1992年发现色球层膨胀速度约为4 km s〜-1，而色球层以5 km s的速度塌陷到光球上在1998-l999年约-1。随着时间的流逝，Ha核心深度与在主导光谱的主要TiO带头中看到的较弱的凹陷变化相关。通过精心的光谱合成计算，我们在近红外中隔离了未混合的金属吸收线，并确定了Z，= 3500 K，log（g）= --0.5（对于太阳金属度）和12±0.5 km s〜-1（对于宏观展宽和vsini） 。半经验拟合产生的色球温度不超过5500 K，但长期变化约400K。该模型的扩展范围超过5000 Ro，并且要求超音速微湍流值范围为19 km s-'，与光球值形成强烈对比仅2 km s-1.我们观察到许多双峰近紫外线发射线的散射核心中多普勒频移只有2 km s -1，这与其发射分量的强度比变化相关。在992年，红色发射分量要强得多，表明色球层流出增加了，为此我们确定球的质量损失率为6 x l0〜-7 Mo yr〜-1。我们提出了对这颗大恒星中色球脉冲的讨论。还介绍了观察到的Mg II h和k线不对称性的详细模型。我们证明，色球Mn I共混物强烈地有助于这种令人困惑的不对称性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号