论文标题
最快旋转O型星的光谱线建模
Spectroscopic Line Modeling of the Fastest Rotating O-type Stars
论文作者
论文摘要
我们对当前已知最快旋转的星星进行光谱分析，VFTS 102（$ v_ {e} \ sin i = 649 \ pm 52 $ km s $ s $ s $^{ - 1} $; o9：vnnne+）和vfts 285（$ v_ {$ v_ {e} \ sin i = 610 \ pm 41 $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ s $ 7： vnnn），大麦芽云中30个DOR综合体的成员。这项研究基于从HST/COS和VLT X-Shooter加上档案VLT长颈鹿光谱的高分辨率紫外光谱。我们利用其光传感，旋转畸变的形状和重力变暗的数值模拟来计算模型光谱线轮廓和预测的单色绝对通量。我们使用引导网格搜索来研究最适合观察到的特征和通量的参数。这些拟合会产生这些恒星的物理参数的估计（加上银河系，$ζ$ OPH），包括赤道旋转速度，倾斜度，半径，质量，质量，重力，温度和红色。我们发现这两个恒星似乎都是径向速度常数。 VFTS 102以临界速度旋转，具有适度的HE富集，并且似乎共享附近OB关联LH 99的运动。这些特性表明，通过近距离二进制合并，恒星旋转。 VFTS 285的旋转价格为$ 95 \％的临界速度，具有强大的HE浓度，并且正在远离30 DOR中心的R136群集。它很可能是由超新星爆炸弹出的逃亡之星，该恒星爆发了出生二进制系统的组件。
We present a spectroscopic analysis of the most rapidly rotating stars currently known, VFTS 102 ($v_{e} \sin i = 649 \pm 52$ km s$^{-1}$; O9: Vnnne+) and VFTS 285 ($v_{e} \sin i = 610 \pm 41$ km s$^{-1}$; O7.5: Vnnn), both members of the 30 Dor complex in the Large Magellanic Cloud. This study is based on high resolution ultraviolet spectra from HST/COS and optical spectra from VLT X-shooter plus archival VLT GIRAFFE spectra. We utilize numerical simulations of their photospheres, rotationally distorted shape, and gravity darkening to calculate model spectral line profiles and predicted monochromatic absolute fluxes. We use a guided grid search to investigate parameters that yield best fits for the observed features and fluxes. These fits produce estimates of the physical parameters for these stars (plus a Galactic counterpart, $ζ$ Oph) including the equatorial rotational velocity, inclination, radius, mass, gravity, temperature, and reddening. We find that both stars appear to be radial velocity constant. VFTS 102 is rotating at critical velocity, has a modest He enrichment, and appears to share the motion of the nearby OB association LH 99. These properties suggest that the star was spun up through a close binary merger. VFTS 285 is rotating at $95\%$ of critical velocity, has a strong He enrichment, and is moving away from the R136 cluster at the center of 30 Dor. It is mostly likely a runaway star ejected by a supernova explosion that released the components of the natal binary system.
