标题： 热星的低分辨率光谱中的恒星标签 - I. HotPayne 方法及 LAMOST DR6 中 330,000 颗恒星的结果 显示英文标题

标题： Stellar labels for hot stars from low-resolution spectra - I. the HotPayne method and results for 330,000 stars from LAMOST DR6

摘要： 我们旨在从热OBA恒星的低分辨率调查光谱中确定恒星标签，这些恒星的有效温度(Teff)高于7500K。 这填补了大型光谱恒星调查如LAMOST在科学分析中的空白，LAMOST为数百万颗恒星提供了R=1800的光谱。 我们首先通过Cramér-Rao界探讨了这类光谱在确定恒星标签方面的理论信息量。 我们表明，在模型光谱完美且观测光谱信噪比为100的极限情况下，可以对广泛的恒星标签进行精确估计：不仅包括有效温度Teff、表面重力logg和投影旋转速度vsini，还包括微观湍流速度、氦丰度和元素丰度[C/H]、[N/H]、[O/H]、[Si/H]、[S/H]和[Fe/H]。 我们的分析表明，大约9500K的温度范围具有挑战性，因为主导的巴尔末和帕申线强度随Teff变化不大。 我们使用Payne方法对LAMOST热星光谱同时拟合这11个恒星标签，利用Kurucz的ATLAS12/SYNTHE LTE光谱作为基础模型。 然后，我们获得了约33万颗具有LAMOST光谱的热星的恒星参数估计，样本规模增加了两个数量级。 其中，约26万颗具有良好的盖亚视差(S/N>5)，其中超过95%是明亮恒星，主要在主序上；其余反映了较低光度的演化恒星，如热亚矮星和白矮星。 我们表明，丰度估计的准确性受到基础模型系统误差的限制，因为它们没有考虑非局部热平衡(NLTE)效应。 最后，我们展示了8000-15000K恒星的vsini详细分布，说明其延伸至临界旋转速度的陡峭截止点，在广泛的温度范围内均如此。 显示英文摘要

摘要： We set out to determine stellar labels from low-resolution survey spectra of hot, OBA stars with effective temperature (Teff) higher than 7500K. This fills a gap in the scientific analysis of large spectroscopic stellar surveys such as LAMOST, which offers spectra for millions of stars at R=1800. We first explore the theoretical information content of such spectra for determining stellar labels, via the Cram\'er-Rao bound. We show that in the limit of perfect model spectra and observed spectra with S/N of 100, precise estimates are possible for a wide range of stellar labels: not only the effective temperature Teff, surface gravity logg, and projected rotation velocity vsini, but also the micro-turbulence velocity, Helium abundance and the elemental abundances [C/H], [N/H], [O/H], [Si/H], [S/H], and [Fe/H]. Our analysis illustrates that the temperature regime of around 9500K is challenging, as the dominant Balmer and Paschen line strength vary little with Teff. We implement the simultaneous fitting of these 11 stellar labels to LAMOST hot-star spectra using the Payne approach, drawing on Kurucz's ATLAS12/SYNTHE LTE spectra as the underlying models. We then obtain stellar parameter estimates for a sample of about 330,000 hot stars with LAMOST spectra, an increase by about two orders of magnitude in sample size. Among them, about 260,000 have good Gaia parallaxes (S/N>5), and more than 95 percent of them are luminous stars, mostly on the main sequence; the rest reflects lower luminosity evolved stars, such as hot subdwarfs and white dwarfs. We show that the fidelity of the abundance estimates is limited by the systematics of the underlying models, as they do not account for NLTE effects. Finally, we show the detailed distribution of vsini of stars with 8000-15,000K, illustrating that it extends to a sharp cut-off at the critical rotation velocity, across a wide range of temperatures.