Physical and Chemical Conditions of the Protostellar Envelope and the Protoplanetary Disk in HL Tau
Physical and Chemical Conditions of the Protostellar Envelope and the Protoplanetary Disk in HL Tau
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DOI：
10.3847/1538-4357/aaed42
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
Chun-Ju Wu;N. Hirano;S. Takakuwa;Hsi-Wei Yen;Yusuke Aso
中科院分区：
文献类型：
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作者：
Chun-Ju Wu;N. Hirano;S. Takakuwa;Hsi-Wei Yen;Yusuke Aso
本文报道了我们对Ⅰ-Ⅱ类原恒星HL Tau的13 CO（2-1）、C18 O（2-1）、SO（56-45）和1.3 mm尘埃连续谱辐射的亚毫米阵（SMA）观测，以及对阿尔马长基线HCO+（1-0）辐射数据的分析。SMA观测到的1.3 mm连续辐射分别具有致密（0.08 × 0.5）和扩展（0.65 × 4.3）两个分量，分别追踪原行星盘和原恒星包层。13 CO、C18 O和HCO+在速度高于系统速度3 km s−1时显示出致密的（1000 Au）成分，在较低速度时显示出扩展的（1000 Au）成分。高速分量跟踪开普勒旋转盘，低速分量跟踪下落包络。HCO+的高速分量是用开普勒圆盘模型拟合的，中心恒星质量为1.4 M。用圆盘+包层模型拟合了13 CO和C18 O沿着盘长轴的径向强度分布，估算出盘和包层的气体质量分别为（2-40）× 10-4 M和M.在文献中，盘状尘埃的质量估计为（1-3）× 10−3 M。因此，我们估计的盘状气体质量表明，盘状气体与尘埃的质量比<10，比包层中的估计比例低10倍。我们讨论了可能的气体耗尽或CO耗尽的行星形成的候选人HL头在磁盘和信封的演变。
We report our Submillimeter Array (SMA) observations of the Class I–II protostar HL Tau in 13CO (2–1), C18O (2–1), SO(56–45), and 1.3 mm dust-continuum emission and our analyses of the ALMA long baseline data of HCO+ (1–0) emission. The 1.3 mm continuum emission observed with the SMA shows compact (∼0.″8 × 0.″5) and extended (∼6.″5 × 4.″3) components, tracing the protoplanetary disk and the protostellar envelope, respectively. The 13CO, C18O, and HCO+ show a compact (∼200 au) component at velocities higher than 3 km s−1 from the systemic velocity and an extended (∼1000 au) component at lower velocities. The high-velocity component traces the Keplerian rotating disk, and the low-velocity component traces the infalling envelope. The HCO+ high-velocity component is fitted with a Keplerian disk model with a central stellar mass of 1.4 M⊙. The radial intensity profiles of 13CO and C18O along the disk major axis are fitted with a disk+envelope model, and the gas masses of the disk and envelope are estimated to be (2–40) × 10–4 M⊙ and M⊙, respectively. The disk dust mass has been estimated to be (1–3) × 10−3 M⊙ in the literature. Thus, our estimated disk gas mass suggests that the gas-to-dust mass ratio in the disk is <10, a factor of 10 lower than the estimated ratio in the envelope. We discuss possible gas depletion or CO depletion in the planet-forming candidate HL Tau in the context of disk and envelope evolution.