光心位移对快速旋转体基本恒星参数的应用极限--以边对边快速旋转体Regulus为例
Application limit of the photocentre displacement to fundamental stellar parameters of fast rotators -- Illustration on the edge-on fast rotator Regulus
摘要：
差分干涉测量法允许获得除光谱之外的差分可见度和相位。微分相位包含了恒星光球层结构和运动的重要信息，如恒星黑子和非径向脉动，特别是自转。因此，这种干涉观测强烈有助于约束恒星的基本参数的快速旋转。光谱天体测量主要使用的是光心位移，这是一个第一次近似的微分相位，只适用于未解决的或边缘的对象。我们在这里研究相关的恒星参数的敏感性模拟的感光中心使用的SCIROCCO代码：一个半解析算法，致力于快速旋转，适用于两个理论建模星的基础上Achernar和Regulus，为了分类这些参数的重要性和它们对建模的影响。我们将我们的模拟与已发表的VLTI/AMBER数据进行比较。目前的工作设置的限制应用的光心位移快速旋转，并在何种条件下，我们可以使用的光心和/或微分相位，通过预先建立的物理标准。为了验证我们的理论研究，我们应用我们的方法分析的观测数据的边缘上的快速旋转轩辕十四。对于不可分辨的目标，在可见度$V\sim 1$下，光心可以约束快速旋转体的主要恒星基本参数，而对于边缘分辨的目标（$0.8 \leq V < 1$），主要是旋转轴位置角（$\rm PA_{\rm rot}$）可以直接从光心位移矢量中推导出来，这对于年轻星团的研究是非常重要的。
英文摘要：
Differential Interferometry allows to obtain the differential visibility and phase, in addition to the spectrum. The differential phase contains important information about the structure and motion of stellar photosphere such as stellar spots and non-radial pulsations, and particularly the rotation. Thus, this interferometric observable strongly helps to constrain the stellar fundamental parameters of fast rotators. The spectro-astrometry mainly uses the photocentre displacements, which is a first approximation of the differential phase, and is applicable only for unresolved or marginally objects. We study here the sensitivity of relevant stellar parameters to the simulated photocentres using the SCIROCCO code: a semi-analytical algorithm dedicated to fast rotators, applied to two theoretical modeling stars based on Achernar and Regulus, in order to classify the importance of these parameters and their impact on the modeling. We compare our simulations with published VLTI/AMBER data. This current work sets the limits of application of photocentre displacements to fast rotators, and under which conditions we can use the photocentres and/or the differential phase, through a pre-established physical criterion. To validate our theoretical study, we apply our method of analysis on observed data of the edge-on fast rotator Regulus. For unresolved targets, with a visibility $V\sim 1$, the photocentre can constrain the main stellar fundamental parameters of fast rotators, whereas from marginally resolved objects ($0.8 \leq V < 1$), mainly the rotation axis position angle ($\rm PA_{\rm rot}$) can be directly deduced from the vectorial photocentre displacement, which is very important for young cluster studies.
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