Fundamental parameters of hot subdwarf stars from the Tycho-Gaia sample

热演化恒星的基本参数，如质量和半径，很难得到约束。热亚矮星（sdO/B）是致密的氦恒星，是热演化恒星的重要组成部分。它们在紫外线中主导着古老的恒星种群，是研究恒星演化过程中特殊事件的关键对象，这些事件包括恒星和行星之间的相互作用或Ia型超新星的前身。随着2016年盖亚任务的精确距离，我们将能够确定这些恒星的基本参数并研究它们的形成。为了实现这一目标，我们必须改进那些特殊目标的大气模型，并使用高质量的同质数据集最大限度地减少系统分类。为了这个项目，我们被允许在艾萨克·牛顿望远镜上使用IDS光谱仪五个晚上。在此提议为这次观察活动提供经费。

The fundamental parameters of hot evolved stars, like masses and radii, are poorly constrained. Hot subdwarf stars (sdO/B) are compact helium stars and constitute an important population of hot evolved stars. They dominate old stellar populations in the ultraviolet and are key objects to study peculiar events in stellar evolution as diverse as the interaction of stars and planets or the progenitors of type Ia supernovae. With accurate distances from the Gaia mission available from 2016 we will be able to determine the fundamental parameters of those stars and study their formation. To achieve this, we have to improve the atmospheric models for those peculiar objects and minimize systematics using a homogeneous dataset of high quality. We were granted five nights with the IDS spectrograph at the Isaac Newton telescope for this project. Here propose funds to cover the expenses of this observing run.