论文标题
磁性和热驱动的磁盘风中的灰尘夹带
Dust entrainment in magnetically and thermally driven disk winds
论文作者
论文摘要
鉴于在原月光磁盘中低粘度的当前范式范围内,磁性和热驱动的磁盘风也获得了流行,即使在存在内部空腔的情况下,这些磁盘仍具有很大的吸积率。在这些风中夹带灰尘的可能性可能解释了最近的散射光观测,并构成了一种向磁盘外部区域的尘埃运输方式。我们旨在研究这些风中的灰尘动态,并在这方面探索光蒸发和磁性磁盘风之间的差异。我们量化了最大可夹住的晶粒尺寸,流动角和一般可检测性。我们使用FARGO3D代码执行全局,2.5D轴对称,非理想的MHD模拟,包括欧姆和双极扩散。灰尘被视为无压液体。使用辐射传输代码RADMC-3D创建合成观测值。我们发现与冷磁风相比,温暖,电离风的尘埃夹带效率(例如光蒸发和磁性风),包括X射线和极端紫外线(XEUV)加热。最大可包含的晶粒尺寸从$ 3 \,μ\ mathrm {m} $到$ 6 \,μ\ mathrm {m {m} $,用于冷磁风的电离风到$ 1 \,μ\ mathrm {m {m {m {m {m {m} $。与温暖的风相比,冷磁风中的灰尘晶粒往往沿较浅的角度流动。随着与中心恒星的距离增加,灰尘夹带效率降低。湍流粘度的较大值会增加可能夹带的灰尘夹带的最大晶粒尺寸半径。我们的模拟表明,在风的外部区域减少灰尘含量可以主要归因于磁盘中的灰尘沉降。在合成图像中,尘土飞扬的风看起来像是一个微弱的圆锥发射区域,对于冷磁风而言更明亮。
Magnetically and thermally driven disk winds have gained popularity in the light of the current paradigm of low viscosities in protoplanetary disks that nevertheless present large accretion rates even in the presence of inner cavities. The possibility of dust entrainment in these winds may explain recent scattered light observations and constitutes a way of dust transport towards outer regions of the disk. We aim to study the dust dynamics in these winds and explore the differences between photoevaporation and magnetically driven disk winds in this regard. We quantify maximum entrainable grain sizes, the flow angle, and the general detectability. We used the FARGO3D code to perform global, 2.5D axisymmetric, nonideal MHD simulations including ohmic and ambipolar diffusion. Dust was treated as a pressureless fluid. Synthetic observations were created with the radiative transfer code RADMC-3D. We find a significant difference in the dust entrainment efficiency of warm, ionized winds such as photoevaporation and magnetic winds including X-ray and extreme ultraviolet (XEUV) heating compared to cold magnetic winds. The maximum entrainable grain size varies from $3\,μ\mathrm{m}$ to $6\,μ\mathrm{m}$ for ionized winds to $1\,μ\mathrm{m}$ for cold magnetic winds. Dust grains in cold magnetic winds tend to flow along a shallower angle compared to the warm winds. With increasing distance to the central star, the dust entrainment efficiency decreases. Larger values of the turbulent viscosity increase the maximum grain size radius of possible dust entrainment. Our simulations indicate that diminishing dust content in the outer regions of the wind can be mainly attributed to the dust settling in the disk. In the synthetic images, the dusty wind appears as a faint, conical emission region which is brighter for a cold magnetic wind.