论文标题
环形磁场中的相对天文统
Relative astrometry in an annular field
论文作者
论文摘要
背景。已反复提出，具有1M级空间望远镜的微弧形水平或下方的相对星形法，作为外观行星检测和表征的工具，以及在天体物理学和基本物理学的最前沿的几个主题。目的。与传统的焦平面成像靠近望远镜光轴的连续区域相比，本文研究了仪器概念的潜在优势。方法。对相对天体的基本方面进行了审查，这是参考恒星在天空上的分布的函数，比g = 12 mag（来自Gaia EDR3）。通过分析和仿真评估目标靶标的田径恒星的统计数据。结果。观察效率受到个人目标知识的好处，因为源模型几乎没有测量。专用观察（10-20小时）可以将系外行星的轨道倾斜限制为几个程度。观察策略可以量身定制，以包括一个恒星样本，实现参考框架，足够大至平均降低残余目录误差到所需的MicroarcSec水平。对于大多数目标，环形场通常提供的参考恒星比常规场相比，在我们的情况下是四到七个。每个目标的最明亮的参考恒星最大2个磁磁力明亮。结论。相对于传统设计，提出的环形场望远镜概念改善了观察灵活性和/或天体性能。因此，这似乎是对未来相对天文法任务的优化的有吸引力的贡献。
Background. Relative astrometry at or below the micro-arcsec level with a 1m class space telescope has been repeatedly proposed as a tool for exo-planet detection and characterization, as well as for several topics at the forefront of Astrophysics and Fundamental Physics. Aim. This paper investigates the potential benefits of an instrument concept based on an annular field of view, as compared to a traditional focal plane imaging a contiguous area close to the telescope optical axis. Method. Basic aspects of relative astrometry are reviewed as a function of the distribution on the sky of reference stars brighter than G = 12 mag (from Gaia EDR3). Statistics of field stars for targets down to G = 8 mag is evaluated by analysis and simulation. Results. Observation efficiency benefits from prior knowledge on individual targets, since source model is improved with few measurements. Dedicated observations (10-20 hours) can constrain the orbital inclination of exoplanets to a few degrees. Observing strategy can be tailored to include a sample of stars, materialising the reference frame, sufficiently large to average down the residual catalogue errors to the desired microarcsec level. For most targets, the annular field provides typically more reference stars, by a factor four to seven in our case, than the conventional field. The brightest reference stars for each target are up to 2 mag brighter. Conclusions. The proposed annular field telescope concept improves on observation flexibility and/or astrometric performance with respect to conventional designs. It appears therefore as an appealing contribution to optimization of future relative astrometry missions.
