AI 中文总结
对遥远贫金属恒星形成区域Sh2-284中年轻恒星物体进行光谱调查，采用基于九个示踪剂的多诊断方法，刻画其恒星和吸积特性，发现贫金属YSOs流量-流量关系有扁平化迹象，表明亚太阳金属丰度环境中气体吸积可有效维持。
AI 中文摘要
我们对朝向银心反方向的遥远（约4.5千秒差距）、低金属丰度（Z约为1/3太阳金属丰度）恒星形成区域Sh2-284中的年轻恒星物体（YSOs）进行了光谱调查。利用中红外斯皮策/IRAC数据以及光学和近红外测光法选择候选YSOs。使用大型双筒望远镜的MODS进行后续光谱观测。我们在贫金属环境中刻画了有盘恒星群体的恒星和吸积特性，探测恒星质量范围从约2.95太阳质量到约0.35太阳质量。这项工作是对Sh2-284中YSOs的首次宽视场（约45'×45'）光谱研究，提供了该银河系环境中恒星形成的全面视图。我们给出了三个低质量目标的铁丰度初步估计值以及有限数量物体的锂丰度，对这些恒星的化学性质进行了初步刻画。我们采用基于九个示踪剂的多诊断方法，利用仪器的光谱覆盖范围，使用H_alpha、H_beta、H_gamma、CaII红外三线系、Pa_eta、Pa_zeta和Pa_epsilon发射线。我们推导关键吸积特性并与附近太阳金属丰度恒星形成区域测量的特性进行比较，以探索潜在的金属丰度驱动的吸积行为和盘演化差异。我们初步发现贫金属YSOs的流量-流量关系与太阳金属丰度样本相比有扁平化迹象，这种行为在各种诊断中都能看到。我们的观测表明，在这个贫金属环境中选定的有盘YSOs表现出有弹性的吸积活动，范围从约2.3×10^(-10)太阳质量/年到约1.0×10^(-6)太阳质量/年，中值速率约为2.2×10^(-8)太阳质量/年。总体而言，这表明在亚太阳金属丰度环境中气体吸积可以有效维持。
英文摘要
We present a spectroscopic survey of young stellar objects (YSOs) in Sh2-284, a distant (~4.5 kpc), low-metallicity (Z~1/3 Zsun) star-forming region (SFR) toward the Galactic anticenter. Candidate YSOs were selected using mid-infrared Spitzer/IRAC data with optical and near-infrared photometry. Follow-up spectroscopy was conducted with MODS at the Large Binocular Telescope. We characterize the stellar and accretion properties of the disk-bearing population in a metal-poor environment, probing stellar masses from ~2.95 Msun to ~0.35 Msun. This work constitutes the first wide-field (~45'x45') spectroscopic investigation of YSOs in Sh2-284, providing a comprehensive view of star formation in this Galactic environment. We provide tentative first estimates of iron abundance for three low-mass targets and lithium abundance for a limited number of objects, offering an initial characterization of the chemical properties of these stars. We adopt a multi-diagnostic approach based on nine tracers, exploiting the spectral coverage of the instrument, using H_alpha, H_beta, H_gamma, CaII infrared triplet, Pa_eta, Pa_zeta, and Pa_epsilon emission lines. We derive key accretion properties and compare them with those measured in nearby, solar-metallicity SFRs to explore potential metallicity-driven differences in accretion behavior and disk evolution. We tentatively find indications of a flattening in the flux-flux relations of the metal-poor YSOs compared to solar-metallicity samples, a behavior that is recovered across diagnostics. Our observations indicate that the selected disk-bearing YSOs in this metal-poor environment exhibit resilient accretion activity, spanning from ~2.3x10^(-10) Msun/yr and ~1.0x10^(-6) Msun/yr, and a median rate of ~2.2x10^(-8) Msun/yr. Overall, this demonstrates that gas accretion can be efficiently sustained in sub-solar metallicity environments.
Comments33 pages, 19 figures, accepted for publication in ApJ
