论文标题

北美和鹈鹕星云地区的年轻恒星的首次广泛的光谱研究

The First Extensive Spectroscopic Study of Young Stars in the North America and Pelican Nebulae Region

论文作者

Fang, Min, Hillenbrand, Lynne A., Kim, Jinyoung Serena, Findeisen, Krzysztof, Herczeg, Gregory J., Carpenter, John M., Rebull, Luisa M., Wang, Hongchi

论文摘要

我们对北美3400多个潜在成员和鹈鹕星云(NAP)进行了光谱调查,该调查使用几个低分辨率($ r \ $ \ $ \ $ 1300-2000)的光谱仪:Palomar/Norris,Wiyn/Hydra,Keck/Keck/Deimos和Mmt/Hect/HectoSpec。我们根据涉及红外过量,Li I 6708吸收,X射线发射,视差和适当的运动的标准,将580个年轻恒星识别为NAP区域的成员。单个光谱的光谱类型是通过与模板拟合的模板来得出的,这些模板要么是序列序列恒星的经验光谱,要么是模型大气。这些模板是人为的遮盖,并且为每个恒星提供了光谱类型和遮面参数的最佳结合。我们使用带有档案光度法的光谱类型来得出$ V $ - 带灭绝和出色的发光度。从H-R图中,年轻恒星的中位年龄约为1 MYR,亮度分散$ \ sim $ 0.3----0.4 dex。我们使用ZTF数据研究了光谱构件样品的光度变异性,并得出结论,当存在的光度变异性并没有显着促进亮度分散体。虽然大于正式错误,但在我们的频谱分型过程中未考虑遮盖物的光度分散剂比未考虑面纱的情况要小。恒星运动基团的测量年龄,结合了Spitzer揭示的嵌入式恒星种群的推断年龄,这表明NAP区域中恒星形成的顺序历史。

We present a spectroscopic survey of over 3400 potential members in the North America and Pelican nebulae (NAP) using several low-resolution ($R\approx$ 1300-2000) spectrographs: Palomar/Norris, WIYN/HYDRA, Keck/DEIMOS, and MMT/Hectospec. We identify 580 young stars as likely members of the NAP region based on criteria involving infrared excess, Li I 6708 absorption, X-ray emission, parallax, and proper motions. The spectral types of individual spectra are derived by fitting them with templates that are either empirical spectra of pre-main sequence stars, or model atmospheres. The templates are artificially veiled, and a best-fit combination of spectral type and veiling parameter is derived for each star. We use the spectral types with archival photometry to derive $V$-band extinction and stellar luminosity. From the H-R diagram, the median age of the young stars is about 1 Myr, with a luminosity dispersion of $\sim$0.3--0.4 dex. We investigate the photometric variability of the spectroscopic member sample using ZTF data, and conclude that photometric variability, while present, does not significantly contribute to the luminosity dispersion. While larger than the formal errors, the luminosity dispersion is smaller than if veiling were not taken into account in our spectral typing process. The measured ages of stellar kinematic groups, combined with inferred ages for embedded stellar populations revealed by Spitzer, suggests a sequential history of star formation in the NAP region.

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