Characterizing exoplanet host stars

在任何系外行星系统中，母恒星在各个方面都主导着该系统：它构成了大部分质量，并代表了主要的能量来源。对于大多数系外行星，唯一能观察到的光是恒星发出的光。然后，这种光通过掩星或多普勒频移等方式受到系外行星的影响而被修正。行星参数--包括质量、半径、辐射环境和平衡温度--是从测量的恒星参数中推断出来的。该团队将使用佐治亚州立大学的CHARA(高角度分辨率天文学中心)阵列，这是世界上最长的基线光学/红外干涉仪，以研究系外行星宿主恒星。他们将确定天体物理参数，包括系统参数的经验值，如凌日系统的行星半径，以及计算的参数，如系统可居住带(HZ)的边界。该团队还将利用他们的干涉观测来确定有行星和没有行星的恒星的半径。这个项目将支持一名研究生的论文研究，并为路易斯安那州立大学的几名本科生提供研究体验。提案团队将通过向社区开放演讲以及通过与美国变星观察者协会的数十名业余爱好者合作来保持公众存在。他们将通过在Reddit上托管的教育项目和通过各种其他媒体渠道进行交流来保持在线存在。研究小组将直接确定大量邻近恒星的物理半径和有效温度，特别是对系外行星宿主。通过长基线光学干涉测量(LBOI)获得的高角度分辨率通常被用来直接测量这类邻近目标的角度尺寸。结合来自LBOI的角度大小、来自依巴谷的三角视差以及通过测光和光谱能量分布拟合的辐射热通量，可以在很大程度上独立于模型确定恒星半径和有效温度。干涉测量目标的大气属性也可以测量，因为它们在附近并且非常明亮，因此允许进行高信噪比观测。同样的数据用于建立半经验的预测关系，将恒星的可观测性与基本性质联系起来，例如表面亮度关系，将恒星的宽带颜色与角半径联系起来。该团队将继续对附近的矮星进行干涉测量，重点放在系外行星宿主恒星上。他们的目标将是建立所有适用的系外行星系统的直接和间接特征。来自该计划的数据在适用的情况下提供了经验系统参数，并改进了恒星模型和参数关系的预测精度，用于描述系外行星系统。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The parent star in any exoplanet system dominates the system in every respect: it comprises most of the mass and represents the principal energy source. For most exoplanets, the only light observed is that emitted by the star. This light is then modified by the influence of the exoplanet through, for instance, occultation or Doppler shifting. Planetary parameters -- including mass, radius, radiation environment, and equilibrium temperature -- are inferred from the measured stellar parameters. The team will use Georgia State University’s CHARA (Center for High Angular Resolution Astronomy) Array, the longest baseline optical/infrared interferometer in the world, to study exoplanet host stars. They will determine astrophysical parameters, including empirical values for the system parameters such as planetary radius for transiting systems, and calculated parameters such as the boundaries of the system habitable zone (HZ). The team will also use their interferometric observations to determine radii for stars with and without planets. This project will support a graduate student’s thesis research, as well as enable research experiences for several undergraduate students at LSU. The proposal team will maintain a public presence by giving talks open to the community and through collaboration with dozens of amateurs from the American Association of Variable Star Observers. They will maintain an online presence through their education program hosted on Reddit and communication through various other media channels. The researdh team will directly determine physical radii and effective temperatures of a large number of nearby stars with a special emphasis on exoplanet hosts. The high angular resolution attainable via long-baseline optical interferometry (LBOI) is routinely used to directly measure the angular sizes of such nearby targets. Combining angular sizes from LBOI, trigonometric parallaxes from Hipparcos, and bolometric fluxes via photometry and spectral energy distribution fitting allows for largely model-independent determinations of stellar radii and effective temperatures. Atmospheric properties for interferometry targets are also possible to measure as they are nearby and very bright, thus allowing for high signal-to-noise observations. The same data serve to establish semi-empirical, predictive relations that tie stellar observables to fundamental properties, such as surface brightness relations, which relate stellar broad band color to angular radius. The team will continue their interferometric survey of nearby dwarf stars with an emphasis on exoplanet host stars. Their aim will be to establish direct and indirect characterizations of all applicable exoplanetary systems. Data from this program provide empirical system parameters where applicable and improve the predictive accuracy of stellar models and parameter relations for the characterization of exoplanetary systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.