A molecular wind from the compact dust disk around CX Tau

We present Keck NIRSPEC+AO high-resolution (R∼25,000), mid-infrared (M-band: 4.6 − 5.2 μm) spectra of the protoplanetary disk CX Tau. Noted for its compact dust disk despite an extended gaseous component in millimeter images, CX Tau provides an ideal setting to study the warm, inner regions of a disk thought to be experiencing pebble drift. Our data covers many 12CO v = 1 − 0 ro-vibrational transitions, in addition to 13CO and 12CO v = 2 − 1. We find no evidence for CO emission in the inner disk of CX Tau at the level of 8 × 1016 cm−2, but do detect narrow, blueshifted absorption at −6 km s−1. A rotation diagram analysis shows that the gas temperature ranges from about 10 to 350 K, with column densities ∼ 9 × 1015 and 3 × 1017 cm−2, respectively. In addition to our Keck-NIRSPEC spectra, we create line maps from archival JWST-MIRI IFU data using custom JDISCS reduction techniques. These maps show spatially extended (∼500 au) H2 and [Ne II]. The blueshifted CO absorption and extended H2 and [Ne II] are evidence of a photoevaporative disk wind. We estimate a wind mass-loss rate from the H2 S(1) line of ∼ 10−9M⊙ yr−1, which is approximately equal to the stellar accretion rate and suggests that CX Tau is in the early stages of disk dispersal.

我们呈现了原行星盘（protoplanetary disk）CX Tau的Keck NIRSPEC+AO高分辨率（R≈25000）中红外（mid-infrared，M波段：4.6−5.2 μm）光谱数据。CX Tau因其尘埃盘紧凑但在毫米图像中具有扩展的气体成分而备受关注，为研究被认为正在经历卵石漂移（pebble drift）的盘的温暖内部区域提供了理想环境。我们的数据覆盖了众多12CO v=1−0转动振动跃迁（ro-vibrational transitions），此外还包括13CO和12CO v=2−1的跃迁。我们未发现CX Tau内部盘存在8×10^16 cm−2水平的CO发射证据，但检测到了位于−6 km/s处的窄蓝移吸收。旋转图分析显示，气体温度范围约为10至350 K，柱密度（column densities）分别约为9×10^15和3×10^17 cm−2。除Keck-NIRSPEC光谱外，我们利用存档的JWST-MIRI IFU数据，通过自定义JDISCS还原技术创建了线图。这些线图显示了空间扩展的H2和[Ne II]。蓝移CO吸收以及扩展的H2和[Ne II]是光蒸发盘风（photoevaporative disk wind）的证据。我们通过H2 S(1)线估计的风质量损失率（mass-loss rate）约为10−9 M⊙/yr，这与恒星吸积率（stellar accretion rate）大致相当，表明CX Tau处于盘消散的早期阶段。