Binary deviations from single object astrometry
Binary deviations from single object astrometry
复制标题
DOI：
10.1093/mnras/staa1148
复制
发表时间：
2020-03
影响因子：
4.8
通讯作者：
Z. Penoyre;V. Belokurov;N. Evans;A. Everall;Sergey E. Koposov
中科院分区：
文献类型：
--
作者：
Z. Penoyre;V. Belokurov;N. Evans;A. Everall;Sergey E. Koposov
大多数二进制文件都未被检测到。假设天体像单点质量一样运动，系统的天体测量缩减可能会受到未分辨的双星的影响。系统的质心(它像点质量一样运动)和光中心(我们所观察到的)之间的差异引入了额外的运动。我们探讨了双星系统对适合天文测量数据的单目标模型的影响程度。这告诉我们观测是如何被双星冲淡的，以及哪些系统造成了最大的差异--但它也允许我们根据观测到的天文测量误差来推断种群的二进制。通过检验模拟观测样本，我们发现周期接近一年的双星可以模拟视差，因此可以模拟距离测量的偏差，而周期较长的双星可以引入显著的视自行。虽然这些变化可以吸收双星带来的一些误差，但从最佳拟合模型的总偏差可以转化为双星在天空中分离的下限。在整个过程中，我们将这些预测与盖亚卫星的数据联系起来，同时让这些结论适用于其他调查。
Most binaries are undetected. Astrometric reductions of a system using the assumption that the object moves like a single point mass can be biased by unresolved binary stars. The discrepancy between the centre of mass of the system (which moves like a point mass) and the centre of light (which is what we observe) introduces additional motion. We explore the extent to which binary systems affect single object model fit to astrometric data. This tells us how observations are diluted by binaries and which systems cause the largest discrepancies – but it also allows us to make inferences about the binarity of populations based on observed astrometric error. By examining a sample of mock observations, we show that binaries with periods close to 1 yr can mimic parallax and thus bias distance measurements, while long-period binaries can introduce significant apparent proper motion. While these changes can soak up some of the error introduced by the binary, the total deviation from the best-fitting model can be translated into a lower limit on the on-sky separation of the pair. Throughout, we link these predictions to data from the Gaia satellite, while leaving the conclusions generalizable to other surveys.