显著的气体，隐秘的尘埃：复杂周期变星的光谱学与色度学
Conspicuous Gas, Cryptic Dust: Spectroscopy and Chromaticity of Complex Periodic Variables
- Caltech/IPAC（加州理工学院/IPAC）
- Carnegie Science Observatories（卡内基科学天文台）
- Department of Astronomy, Caltech（加州理工学院天文学系）
- Kavli Institute for Astrophysics and Space Research, MIT（麻省理工学院卡弗里天体物理与空间研究所）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
针对4颗复杂周期变星，通过多台设备的光谱与测光观测，发现其凌星凹陷源于带不透明核心和光学薄晕的含尘等离子体团块，相关观测将用于验证尘埃起源的解释。
AI中文摘要：
复杂周期变星（CPVs）是年轻的低质量恒星，其光变曲线显示出周期性的凹陷，这表明存在共转的凌星物质，而这种物质的起源和组成尚不清楚。本文呈现了利用麦哲伦望远镜、凯克望远镜、海尔望远镜、MuSCAT1、MuSCAT2、Tierras、KeplerCam和TESS对4颗CPVs开展的新光学与近红外光谱及测光观测。光谱显示，凌星外的巴尔末发射线随时间呈正弦变化，凌星时巴尔末发射线变暗，这表明CPVs拥有受磁场束缚的星周等离子体团块。然而，星周氢发射率在不同夜晚存在大幅变化，且光变曲线形态无明显改变，这说明尖锐的流量凹陷并非由星周等离子体造成，而是由尘埃导致。光学色度（凹陷深度与λ^(-β)成正比，β=0.79±0.16）支持这一结论，但该幂律在近红外波段出现断裂，单一幂律会低估2.1微米处观测到的凹陷深度。因此，本文倾向于凹陷由带有不透明核心和光学薄晕的含尘等离子体团块引发，不过无法排除尘埃特性随恒星或历元变化的模型。波长大于2微米和小于0.4微米的观测将验证这一解释并明确尘埃的起源。
英文摘要：
Complex periodic variables (CPVs) are young low-mass stars whose light curves show periodic dips indicative of transiting corotating material. The origin and composition of this material are unclear. Here we present new optical and near-infrared spectroscopy and photometry of four CPVs from Magellan, Keck, Hale, MuSCAT1, MuSCAT2, Tierras, KeplerCam, and TESS. The spectra imply that CPVs host magnetically bound circumstellar plasma clumps, on the basis of sinusoidal-in-time Balmer emission out of transit, and Balmer dimming during transit. Yet large night-to-night changes in circumstellar hydrogen emissivity occur without clear changes in light curve morphology, suggesting that the sharp flux dips are caused not by circumstellar plasma but by dust. Optical chromaticities (depth proportional to $λ^{-β}$, with $β$ = 0.79 $\pm$ 0.16) support this, but the power law breaks in the near-infrared, where a single power law under-predicts the depths observed at 2.1 microns. We therefore favor dips caused by dusty plasma clumps with opaque cores and optically thin halos, though we cannot rule out models in which the dust properties vary per-star or per-epoch. Observations at wavelengths greater than 2 microns and less than 0.4 microns would test this interpretation and clarify the dust's origin.
