A Detached Protostellar Disk around a ∼0.2 M⊙ Protostar in a Possible Site of a Multiple Star Formation in a Dynamical Environment in Taurus
A Detached Protostellar Disk around a ∼0.2 M⊙ Protostar in a Possible Site of a Multiple Star Formation in a Dynamical Environment in Taurus
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金牛座动态环境中多恒星形成的可能地点中约 0.2 M⊙ 原恒星周围的分离原恒星盘
DOI：
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
K. Tachihara
中科院分区：
文献类型：
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作者：
K. Tokuda;T. Onishi;K. Saigo;T. Hosokawa;Tomoaki Matsumoto;S. Inutsuka;M. Machida;K. Tomida;M. Kunitomo;A. Kawamura;Y. Fukui;K. Tachihara
我们报告了ALMA在0.87 mm连续体和12CO （J = 3-2）中对一颗极低亮度（<0.1 L⊙）的原恒星的观测，该原恒星深嵌在金牛座最致密的核心之一MC27/L1521F中，表明在高度动态的环境中存在多星形成。光束的大小对应于~ 20au，我们已经清楚地检测到与原恒星相关的12CO中的蓝移/红移气体。气体的空间/速度分布表明，存在一个大小为~ 10 au的旋转圆盘，圆盘质量为~ 10−4 M⊙，中心恒星质量为~ 0.2 M⊙。观测到的圆盘似乎与周围的致密气体分离，尽管它仍然嵌入密度为~ 106 cm−3的核心中心。目前的低流出活动和非常低的光度表明，尽管恒星形成的阶段非常早，但原恒星的质量吸积速率非常低。我们可能正在见证一颗~ 0.2 M⊙原恒星形成的最后阶段。然而，我们不能用标准的主序前演化轨迹来解释观测到的低光度，除非我们假设原恒星的初始半径极小（~ 0.65）。这些事实可能会挑战我们目前对低质量恒星形成的理解，特别是对原恒星和星周盘的质量吸积过程。
We report ALMA observations in 0.87 mm continuum and 12CO (J = 3–2) toward a very low-luminosity (<0.1 L⊙) protostar, which is deeply embedded in one of the densest cores, MC27/L1521F, in Taurus with an indication of multiple star formation in a highly dynamical environment. The beam size corresponds to ∼20 au, and we have clearly detected blueshifted/redshifted gas in 12CO associated with the protostar. The spatial/velocity distributions of the gas show there is a rotating disk with a size scale of ∼10 au, a disk mass of ∼10−4 M⊙, and a central stellar mass of ∼0.2 M⊙. The observed disk seems to be detached from the surrounding dense gas, although it is still embedded at the center of the core whose density is ∼106 cm−3. The current low-outflow activity and the very low luminosity indicate that the mass accretion rate onto the protostar is extremely low in spite of a very early stage of star formation. We may be witnessing the final stage of the formation of ∼0.2 M⊙ protostar. However, we cannot explain the observed low luminosity with the standard pre-main-sequence evolutionary track unless we assume cold accretion with an extremely small initial radius of the protostar (∼0.65 ). These facts may challenge our current understanding of the low mass star formation, in particular the mass accretion process onto the protostar and the circumstellar disk.
影响因子：
4.9
作者：
Baraffe, I.;Vorobyov, E.;Chabrier, G.
通讯作者：
Chabrier, G.