标题： VLTI 对猎户座腰带恒星的观测：I. 猎户座ε 显示英文标题

标题： VLTI observations of the Orion Belt stars: I. eps Orionis

摘要： 大质量恒星在宇宙的演化中起着决定性的作用。 为了限制它们当前的状态和结构，我们需要足够复杂的模型，并由天体测量、干涉测量和光谱观测进行约束。 然而，这些模型并不适用于遥远的恒星。 相反，我们专注于猎户座腰带中的最近的大质量恒星。 我们获得了猎户座腰带恒星的VLTI干涉测量观测数据，并校准了GRAVITY和PIONIER仪器的可见度数据。 此外，我们还从CFHT和CTIO天文台获得了光谱数据。 在建模方面，我们使用了经过修改的PHOEBE2版本，并扩展了新的干涉测量和光谱模块。 为了描述非球形、旋转或罗奇型恒星，必须使用合成光谱的广泛网格计算三角形网格上的积分。 对于拟合，我们使用了单纯形算法和参数空间的chi2映射。 在本文中，我们展示了B0Ia超巨星eps Ori的单星模型。 干涉测量可见度表明，这颗恒星不是球形的，而是接近其临界速度旋转。 首选距离d=(384+-8)pc，对应于猎户座OB1b星协的距离中位数。 我们得到了以下参数：m=(28.4+-2.0)Msol，R=(27.6+-1.5)Rsol，Teff=25000 K，i=45deg，升交点经度，Omega=300deg，以及Prot=4.3+1.0d。 这个折中模型对无风的巴尔末线轮廓提供了合理的拟合，但干涉测量和光谱数据集之间仍存在一些矛盾，对应于快速旋转与慢速旋转的恒星。 我们的快速旋转模型表明，应该自然存在周围物质，以风或盘的形式存在，并对连续辐射作出贡献。 eps Ori的快速旋转与合并相容，这种合并可能来自质量相近的多恒星系统，如del、zet或sig Ori。 显示英文摘要

摘要： Massive stars play a decisive role in the evolution of the Universe. In order to constrain their current state and structure, we need sufficiently complex models, constrained by astrometric, interferometric, and spectroscopic observations. However, they are not available for distant stars. Instead, we focused on the nearest massive stars in the Orion Belt. We obtained VLTI interferometric observations of Orion Belt stars and calibrated visibility data from the GRAVITY and PIONIER instruments. Additionally, we obtained spectroscopic data from the CFHT and CTIO observatories. For modelling, we used a modified version of PHOEBE2, extended with new interferometric and spectroscopic modules. To describe non-spherical, rotating, or Roche-like stars, integrals over triangular meshes have to be computed, using extensive grids of synthetic spectra. For fitting, we used the simplex algorithm and chi2 mapping of the parameter space. In this paper, we present single-star models of the B0Ia supergiant eps Ori. Interferometric visibilities indicate that the star is not spherical but rotating close to its critical velocity. The preferred distance, d=(384+-8)pc, corresponds to the median of distances for the Orion OB1b association. We obtained the following parameters: m=(28.4+-2.0)Msol, R=(27.6+-1.5)Rsol, Teff=25000 K, i=45deg, longitude of the ascending node, Omega=300deg, and Prot=4.3+1.0d. This compromise model provides a reasonable fit to wind-free Balmer line profiles, but there is still some tension between interferometric and spectroscopic datasets, corresponding to a faster- vs. slower-rotating star. Our fast-rotating model implies that circumstellar matter should be naturally present, in the form of wind or disk, and contribute to continuum radiation. The fast rotation of eps Ori is compatible with a merger, formed from a multiple system of comparable mass, like del, zet or sig Ori.