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The young protostellar disc in IRAS 16293−2422 B is hot and shows signatures of gravitational instability
Monthly Notices of the Royal Astronomical Society ( IF 4.7 ) Pub Date : 2021-09-16 , DOI: 10.1093/mnras/stab2657
Joaquin Zamponi, María José Maureira, Bo Zhao, Hauyu Baobab Liu, John D Ilee, Duncan Forgan, Paola Caselli

Deeply embedded protostars are actively fed from their surrounding envelopes through their protostellar disc. The physical structure of such early discs might be different from that of more evolved sources due to the active accretion. We present 1.3 and 3 mm ALMA continuum observations at resolutions of 6.5 and 12 au, respectively, towards the Class 0 source IRAS 16293−2422 B. The resolved brightness temperatures appear remarkably high, with Tb > 100 K within ∼30 au and Tb peak over 400 K at 3 mm. Both wavelengths show a lopsided emission with a spectral index reaching values less than 2 in the central ∼20 au region. We compare these observations with a series of radiative transfer calculations and synthetic observations of magnetohydrodynamic and radiation hydrodynamic protostellar disc models formed after the collapse of a dense core. Based on our results, we argue that the gas kinematics within the disc may play a more significant role in heating the disc than the protostellar radiation. In particular, our radiation hydrodynamic simulation of disc formation, including heating sources associated with gravitational instabilities, is able to generate the temperatures necessary to explain the high fluxes observed in IRAS 16293B. Besides, the low spectral index values are naturally reproduced by the high optical depth and high inner temperatures of the protostellar disc models. The high temperatures in IRAS 16293B imply that volatile species are mostly in the gas phase, suggesting that a self-gravitating disc could be at the origin of a hot corino.

中文翻译:

IRAS 16293-2422 B 中的年轻原恒星盘很热,并显示出引力不稳定性的特征

深深嵌入的原恒星通过它们的原恒星盘从周围的信封中得到积极的喂养。由于活跃的吸积,这种早期圆盘的物理结构可能与更进化的来源不同。我们分别以 6.5 和 12 au 的分辨率对 0 类源 IRAS 16293-2422 B 进行 1.3 和 3 毫米 ALMA 连续谱观测。分辨的亮温看起来非常高,Tb > 100 K 在 ∼30 au 和 Tb 在 3 mm 处超过 400 K 的峰值。两种波长都显示出不平衡的发射,光谱指数在中心~20 au 区域达到小于 2 的值。我们将这些观测结果与一系列辐射传输计算以及对致密核心坍塌后形成的磁流体动力学和辐射流体动力学原恒星盘模型的综合观测结果进行比较。根据我们的结果,我们认为圆盘内的气体运动学在加热圆盘方面可能比原恒星辐射发挥更重要的作用。特别是,我们对圆盘形成的辐射流体动力学模拟,包括与重力不稳定性相关的加热源,能够产生解释在 IRAS 16293B 中观察到的高通量所需的温度。此外,原恒星盘模型的高光学深度和高内部温度自然地再现了低光谱指数值。IRAS 16293B 的高温意味着挥发性物质主要处于气相,这表明自引力盘可能是热科里诺的起源。我们认为,圆盘内的气体运动学在加热圆盘方面可能比原恒星辐射发挥更重要的作用。特别是,我们对圆盘形成的辐射流体动力学模拟,包括与重力不稳定性相关的加热源,能够产生解释在 IRAS 16293B 中观察到的高通量所需的温度。此外,原恒星盘模型的高光学深度和高内部温度自然地再现了低光谱指数值。IRAS 16293B 的高温意味着挥发性物质主要处于气相,这表明自引力盘可能是热科里诺的起源。我们认为,圆盘内的气体运动学在加热圆盘方面可能比原恒星辐射发挥更重要的作用。特别是,我们对圆盘形成的辐射流体动力学模拟,包括与重力不稳定性相关的加热源,能够产生解释在 IRAS 16293B 中观察到的高通量所需的温度。此外,原恒星盘模型的高光学深度和高内部温度自然地再现了低光谱指数值。IRAS 16293B 的高温意味着挥发性物质主要处于气相,这表明自引力盘可能是热科里诺的起源。包括与重力不稳定性相关的加热源,能够产生解释在 IRAS 16293B 中观察到的高通量所需的温度。此外,原恒星盘模型的高光学深度和高内部温度自然地再现了低光谱指数值。IRAS 16293B 的高温意味着挥发性物质主要处于气相,这表明自引力盘可能是热科里诺的起源。包括与重力不稳定性相关的加热源,能够产生解释在 IRAS 16293B 中观察到的高通量所需的温度。此外,原恒星盘模型的高光学深度和高内部温度自然地再现了低光谱指数值。IRAS 16293B 的高温意味着挥发性物质主要处于气相,这表明自引力盘可能是热科里诺的起源。
更新日期:2021-09-16
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