We have completed an optical spectroscopic survey of a sample of candidate young stars in the Serpens Main star-forming region selected from deep B, V, and R band images. While infrared, X-ray, and optical surveys of the cloud have identified many young stellar objects (YSOs), these surveys have been biased toward particular stages of pre-main sequence evolution. We have obtained over 700 moderate resolution optical spectra that, when combined with published data, have led to the identification of 63 association members based on the presence of Hα in emission, lithium absorption, X-ray emission, a mid-infrared excess, and/or reflection nebulosity. Twelve YSOs are identified based on the presence of lithium absorption alone. An additional 16 objects are classified as possible association members and their pre-main sequence nature is in need of confirmation. Spectral types along with V and R band photometry were used to derive effective temperatures and bolometric luminosities for association members to compare with theoretical tracks and isochrones for pre-main sequence stars. An average age of 2 Myr is derived for this population. When compared to simulations, there is no obvious evidence for an age spread when considering the major sources of uncertainties in the derived luminosities. However when compared to the young cluster in Ophiuchus, the association members in Serpens appear to have a larger spread in luminosities and hence ages which could be intrinsic to the region or the result of a foreground population of YSOs associated with the Aquila Rift. Modeling of the spectral energy distributions from optical through mid-infrared wavelengths has revealed three new transition disk objects, making a total of six in the cluster. Echelle spectra for a subset of these sources enabled estimates of v sin i for seven association members. Analysis of gravity-sensitive lines in the echelle and moderate resolution spectra of the association members indicate surface gravities consistent with dwarf or sub-giant stars.
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机译：我们已经完成了对从深层B，V和R波段图像中选出的Serpens Main恒星形成区域中候选年轻恒星样本的光学光谱调查。尽管对云的红外，X射线和光学勘测确定了许多年轻的恒星物体（YSO），但这些勘测偏向于主序列前演化的特定阶段。我们已经获得了700多个中等分辨率的光谱，与公开的数据相结合，可以根据发射，锂吸收，X射线发射，中红外过量和/或反射星云。仅根据锂吸收的存在鉴定出十二种YSO。另外的16个对象被分类为可能的关联成员，并且它们的主前序列性质需要确认。光谱类型与V和R波段光度法一起用于得出关联成员的有效温度和辐射热亮度，以与主航母前恒星的理论轨道和等时线进行比较。该人群的平均年龄为2 Myr。当与模拟进行比较时，当考虑得出的亮度的主要不确定性来源时，没有明显的年龄扩散证据。但是，与蛇夫座的年轻星团相比，瑟彭斯的同伴成员的光度分布更大，因此年龄可能是该地区固有的，或者是与天鹰座裂谷有关的YSO前景种群的结果。对从光波长到中红外波长的光谱能量分布进行建模后，发现了三个新的过渡盘物体，总共有六个。这些来源的子集的Echelle光谱可以估计七个关联成员的v sin i。通过对阶梯波的重力敏感线和相关成员的中等分辨率谱图的分析，可以得出与矮星或超巨星恒星相符的表面重力。
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