论文标题
ALMA多波段观测显示的大规模紧凑型灰尘磁盘在CW TAU周围有一个差距
Massive compact dust disk with a gap around CW Tau revealed by ALMA multi-band observations
论文作者
论文摘要
半径为$ \ Lessim $ 50 au的紧凑型原行星磁盘在年轻的低质量恒星周围很常见。我们报告了高分辨率的Alma Dust Continuum观测值，该观测值是在Band 4（$λ= 2.2 $ mm），6（1.3 mm），7（0.89 mm）和8（0.75 mm）的CW Tau周围的紧凑型磁盘。 SED显示了$ 2.0 \ pm0.24 $的光谱坡度在0.75至1.3毫米之间，而$ 3.7 \ pm0.29 $在2.17至3.56毫米之间。 2.17至3.56毫米之间的陡坡与小谷物的光学薄发射（$ \ lyssim $ 350 $ {\ rmμm} $）一致。我们执行ALMA数据的参数拟合以表征灰尘磁盘。有趣的是，如果尘埃气质量比为0.01，则Toomre的Q参数达到$ \ sim $ 1-3，这表明CW TAU磁盘可能在重力上可能不稳定。总灰尘质量估计为$ \ sim250m _ {\ oplus} $，最大灰尘尺寸为140 $ {\rmμm} $，从以前的7频段7 polarimetric观察和至少8000万美元_ {\ oplus} $中推断出。该结果表明，尽管CW Tau磁盘较小，但CW Tau磁盘仍然很大。此外，我们清楚地确定了位于$ \ sim20 $ au的间隙结构，该结构可能是由巨型星球引起的。尽管具有这些有趣的特征，但CW TAU磁盘在ALMA带6处具有正常的磁盘光度，大小和光谱指数，这可能是II类磁盘中质量预算问题的线索。
Compact protoplanetary disks with a radius of $\lesssim$ 50 au are common around young low-mass stars. We report high resolution ALMA dust continuum observations toward a compact disk around CW Tau at Band 4 ($λ=2.2$ mm), 6 (1.3 mm), 7 (0.89 mm) and 8 (0.75 mm). The SED shows the spectral slope of $2.0\pm0.24$ between 0.75 and 1.3 mm, while it is $3.7\pm0.29$ between 2.17 and 3.56 mm. The steep slope between 2.17 and 3.56 mm is consistent with that of optically thin emission from small grains ($\lesssim$ 350 ${\rm μm}$). We perform parametric fitting of the ALMA data to characterize the dust disk. Interestingly, if the dust-to-gas mass ratio is 0.01, the Toomre's Q parameter reaches $\sim$ 1-3, suggesting that the CW Tau disk might be marginally gravitationally unstable. The total dust mass is estimated as $\sim250M_{\oplus}$ for the maximum dust size of 140 ${\rm μm}$ that is inferred from the previous Band 7 polarimetric observation and at least $80M_{\oplus}$ even for larger grain sizes. This result shows that the CW Tau disk is quite massive in spite of its smallness. Furthermore, we clearly identify a gap structure located at $\sim20$ au, which might be induced by a giant planet. In spite of these interesting characteristics, the CW Tau disk has normal disk luminosity, size and spectral index at ALMA Band 6, which could be a clue to the mass budget problem in Class II disks.
