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arXiv 1503.00807astro-ph.SR
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原行星盘[C I] $^3$ P PDMATHAAB- $^3$ P $_0$发射的首次探测

First Detection of [C I] $^3$P$_1$-$^3$P$_0$ Emission from a Protoplanetary Disk

Takashi Tsukagoshi, Munetake Momose, Masao Saito, Yoshimi Kitamura, Yoshito Shimajiri, Ryohei Kawabe

摘要:

我们使用安装在阿塔卡马亚毫米望远镜实验(ASTE)上的阿塔卡马大毫米/亚毫米阵列(ALMA)波段8鉴定模型接收机,对三颗金牛座T星(DM Tau、LkCa 15和TW Hya)进行了单点[C I] $^3$ P $_1$ - $^3$ P $_0$和CO J=4-3观测。在金牛座L1551区域也观测到两颗原恒星,L1551 IRS 5和HL Tau。我们成功地探测到了来自DM Tau周围的原行星盘以及原恒星目标的[C I]发射。来自原行星盘的[C I]发射的光谱轮廓是边缘单峰的,表明原子碳(C)向最外层盘延伸。探测到的[C I]发射是光学薄的,估计金牛座T星目标和原恒星的C柱密度分别为<~10 $^{16}$ cm $^{-2}$和~10 $^{17}$ cm $^{-2}$。我们发现金牛座T星和原恒星目标之间的碳与尘埃的总质量比$M$(C)/ $M$(尘埃)存在明显差异;金牛座T星的$M$(C)/ $M$(尘埃)比原恒星小一个数量级。盘源的$M$(C)/ $M$(尘埃)比值的降低与理论预测一致,即原子C只能在盘的近表面层存活,C $^+$ /C/CO跃迁发生在盘中平面更深的地方。

英文摘要:

We performed single point [C I] $^3$P$_1$-$^3$P$_0$ and CO J=4-3 observations toward three T Tauri stars, DM Tau, LkCa 15, and TW Hya, using the Atacama Large Millimeter/submillimeter Array (ALMA) Band 8 qualification model receiver installed on the Atacama Submillimeter Telescope Experiment (ASTE). Two protostars in the Taurus L1551 region, L1551 IRS 5 and HL Tau, were also observed. We successfully detected [C I] emission from the protoplanetary disk around DM Tau as well as the protostellar targets. The spectral profile of the [C I] emission from the protoplanetary disk is marginally single-peaked, suggesting that atomic carbon (C) extends toward the outermost disk. The detected [C I] emission is optically thin and the column densities of C are estimated to be <~10$^{16}$ cm$^{-2}$ and ~10$^{17}$ cm$^{-2}$ for the T Tauri star targets and the protostars, respectively. We found a clear difference in the total mass ratio of C to dust, $M$(C)/$M$(dust), between the T Tauri stars and protostellar targets; the $M$(C)/$M$(dust) ratio of the T Tauri stars is one order of magnitude smaller than that of the protostars. The decrease of the estimated $M$(C)/$M$(dust) ratios for the disk sources is consistent with a theoretical prediction that the atomic C can survive only in the near surface layer of the disk and C$^+$/C/CO transition occurs deeper into the disk midplane.

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