AI 中文总结
该研究以LAMOST DR5的159颗CAe星为样本，用低分辨率Hα和CaII红外三线诊断其星周盘，可靠测定盘质量与倾角，明确盘质量分布、盘-星质量比及CaII发射体的盘质量特征。
AI 中文摘要
经典Ae星（CAe）是处于主序的A型星，具有Hα发射线但无尘埃特征，被认为是经典Be（CBe）星向更低恒星质量延伸的冷端天体。我们研究了低光谱分辨率（R=1800）下观测到的Hα与CaII红外三线对CAe星周盘的诊断作用。利用LAMOST巡天（DR5）中159颗CAe星样本，我们发现可通过低分辨率Hα轮廓可靠测定星周盘质量及恒星-盘的视线倾角。CAe星的盘质量分布与晚型CBe星的先前结果范围吻合，不过最新CAe光谱次型（A3与A4）的盘质量存在明显增加，我们将其归因于选择效应。在A2至B6光谱范围内，CAe与CBe星的平均盘-星质量比一致，log₁₀(M_disk/M_*)=-9.1。CAe样本中的少数天体（约16%）还呈现CaII红外三线发射，观测到的发射完全处于盘模型的预测范围内，且有统计证据表明CaII发射体的Hα盘质量系统性更大。
英文摘要
Classical Ae stars (CAe) are main sequence, A-type stars with H$α$ emission but no signature of dust; they are thought to be the cool extension of the classical Be (CBe) stars to lower stellar masses. We investigate the use of H$α$ and the CaII IR triplet observed at low spectroscopic resolution ($R=1800$) as diagnostics for the circumstellar disks of the CAe stars. Using a sample of 159 CAe stars from the LAMOST survey (DR5), we find that circumstellar disk masses and star/disk viewing inclination angles can be reliably determined from low resolution H$α$ profiles. The CAe disk mass distribution agrees well with the previous range found for late-type CBe stars, although there is an apparent increase in disk mass for the latest CAe spectral sub-types (A3 and A4) which we attribute to selection effects. Over the spectral range A2 through B6, the average disk-to-star mass ratio for the CAe and CBe stars is consistent with $\log_{10}(M_{\rm disk}/M_*)=-9.1$. A minority of the CAe sample ($\sim$16%) also show emission in the CaII IR triplet. The observed emission is well within the range predicted by the disk models, and there is statistical evidence that the CaII emitters have systematically larger H$α$ disk masses.
Comments18 pages, 13 figures and 3 tables. Accepted for publication in The Astrophysical Journal
