A volume-limited sample of hot subdwarf stars

炽热的亚矮星(SDO/B)构成了一大批微弱的蓝色恒星。它们的形成仍然不清楚，因为只有在前身恒星经过红巨星分支后几乎完全失去包层的情况下，它们才能形成。二元相互作用可能在解释这种质量损失中起到重要作用，并且已经提出了几种形成假说。对于不同的形成场景，计算出的演化轨迹通常与观测到的热次矮星样本进行比较。然而，由于到目前为止所有观测样本的不完备性和不均质性，模型与观测数据之间的这种比较总是受到相当严重的选择效应的影响。在这里，我们建议汇编第一个完整的、数量有限的热次矮星样本，以消除这些选择效应，并对演化情景施加更强的约束。将对完整的样品进行光谱观测，并将开发和测试数据分析管道，为未来的大型光谱调查做准备。

Hot subdwarf stars (sdO/Bs) constitute a prominent population of faint blue stars. Their formation is still unclear, because they can only be formed if the progenitor star loses its envelope almost entirely after passing the red-giant branch. Binary interactions likely play an important role to explain this mass loss and several formation scenarios have been proposed. Evolutionary tracks calculated for the diverse formation scenarios are usually compared to observed samples of hot subdwarf stars. However, this comparison between models and observational data is always biased by quite severe selection effects due to the incompleteness and inhomogeneity of all the observed samples so far. Here we propose to compile the first complete, volume-limited sample of hot subdwarfs to eliminate those selection effects and put much stronger constraints on evolutionary scenarios. The complete sample will be observed spectroscopically and a data analysis pipeline will be developed and tested to prepare for the large spectroscopic surveys in the future.