TW Hya星盘亚结构尘埃含量的特征
Characterizing the dust content of disk substructures in TW Hya
摘要：
我们目前的阿塔卡马大型毫米阵列（ALMA）的TW Hya在3.1毫米的$\sim50$毫角秒分辨率的意见。这些新的数据相结合的档案高角分辨率ALMA观测在0.87毫米，1.3毫米，和2.1毫米。我们分析这些多波长的数据来推断磁盘径向轮廓的尘埃表面密度，最大粒径，粒径分布和斜率。大多数以前已知的环形子结构的磁盘TW Hya的解决在四个波长。在内部3金腔，2.1毫米和3.1毫米的图像显示了一个紧凑的自由-自由发射源，可能与电离射流。我们的尘埃排放的多波长分析表明，TW Hya的磁盘中的最大颗粒尺寸为$>1$ mm。内部20金是完全光学厚的所有四个波段，这导致在不同的波长跟踪不同的磁盘高度的数据。再加上尘埃沉降的影响，这就妨碍了对这些地区的密度和粒度进行准确的估计。在$r>20$ au，我们发现在明亮的环的位置有大尘埃颗粒积聚的证据，表明这些是作为尘埃陷阱工作的。盘中的总灰尘质量在250和330 $M_{\oplus}$之间，这表示气体与灰尘的质量比在50和70之间。我们的质量测量值比使用大型人口调查的典型假设估计的质量高4.5-5.9倍。我们的研究结果表明，TW Hya的环子结构是触发流动不稳定性和形成新一代星子的理想位置。
英文摘要：
We present Atacama Large Millimeter Array (ALMA) observations of TW Hya at 3.1 mm with $\sim50$ milliarcsecond resolution. These new data were combined with archival high angular resolution ALMA observations at 0.87 mm, 1.3 mm, and 2.1 mm. We analyze these multi-wavelength data to infer a disk radial profile of the dust surface density, maximum particle size, and slope of the particle size distribution. Most previously known annular substructures in the disk of TW Hya are resolved at the four wavelengths. Inside the inner 3 au cavity, the 2.1 mm and 3.1 mm images show a compact source of free-free emission, likely associated with an ionized jet. Our multi-wavelength analysis of the dust emission shows that the maximum particle size in the disk of TW Hya is $>1$ mm. The inner 20 au are completely optically thick at all four bands, which results in the data tracing different disk heights at different wavelengths. Coupled with the effects of dust settling, this prevents the derivation of accurate density and grain size estimates in these regions. At $r>20$ au, we find evidence of the accumulation of large dust particle at the position of the bright rings, indicating that these are working as dust traps. The total dust mass in the disk is between 250 and 330 $M_{\oplus}$, which represents a gas-to-dust mass ratio between 50 and 70. Our mass measurement is a factor of 4.5-5.9 higher than the mass that one would estimate using the typical assumptions of large demographic surveys. Our results indicate that the ring substructures in TW Hya are ideal locations to trigger the streaming instability and form new generations of planetesimals.
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