蛇夫座恒星形成复合体中18个Class II盘的200-300 GHz巡测
The 200-300 GHz Survey for 18 Class II Disks in the Ophiuchus Star-Forming Complex
- National Sun Yat-Sen University（国立中山大学）
- Johns Hopkins University（约翰斯·霍普金斯大学）
- Center of Astronomy and Gravitation, National Taiwan Normal University（国立台湾师范大学天文与引力研究中心）
- National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
- University of Chinese Academy of Sciences（中国科学院大学）
- Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森天体物理中心）
- Department of Astronomy, University of California, Berkeley（加州大学伯克利分校天文学系）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用SMA巡测蛇夫座18个Class II盘的200-300 GHz辐射，发现其谱指数接近2，表明辐射由光学厚尘埃主导，且盘大小与光度正相关，挑战了小盘即尘埃耗尽的传统观点。
AI中文摘要：
我们使用亚毫米波阵列（SMA）测量了蛇夫座恒星形成复合体中18个Class II原行星盘在198-310 GHz频段的流量密度。这些盘的$\sim$200-300 GHz谱指数（$\alpha_{200-300}$）为$2.3^{+0.2}_{-0.5}$。在该观测频段内，蛇夫座盘的辐射特性与先前SMA巡测中观测到的金牛-御夫座区域48个空间紧凑的Class II盘非常相似。将蛇夫座和金牛-御夫座样本合并后，$\alpha_{200-300}$与250 GHz流量密度（$F_{250\\,\mathrm{GHz}}$）之间的皮尔逊相关系数为0.27（$p=0.02$）。我们未发现$\alpha_{200-300}$与盘的$R_{95\\%}$半径之间存在令人信服的相关性。我们对空间紧凑盘中$\alpha_{200-300}$值接近2的解释是：在$\gtrsim$200 GHz频率下，这些盘中的连续谱辐射由光学厚尘埃热辐射主导，且与$F_{250\\,\mathrm{GHz}}$和$R_{95\\%}$无关。因此，（亚）毫米光度与视盘大小呈正相关，这一现象已在众多Class II盘的高分辨率辐射巡测中被发现。在年龄为$\sim$1-2 Myr的年轻星团中，具有较小半径或较低（亚）毫米光度的Class II盘不一定就是尘埃质量预算已被消耗或消散的盘。
英文摘要：
We measured the 198-310 GHz flux densities of 18 Class II protoplanetary disks in the Ophiuchus star-forming complex using the Submillimeter Array (SMA). The $\sim$200-300 GHz spectral indices ($α_{200-300}$) of these disks are $2.3^{+0.2}_{-0.5}$. In this observed frequency range, emission properties of the Ophiuchus disks are very similar to the 48 spatially compact Class II disks in the Taurus-Auriga region observed in a previous SMA survey. Combining the Ophiuchus and Taurus-Auriga samples, the Pearson correlation coefficient between $α_{200-300}$ and the flux density at 250 GHz ($F_{250\,\mathrm{GHz}}$) is 0.27 ($p=0.02$). We do not find a convincing correlation between $α_{200-300}$ and the $R_{95\%}$ radius of the disks. Our interpretation for the $α_{200-300}$ values being close to 2 in the spatially compact disks is that at $\gtrsim 200$ GHz frequencies, the continuum emission in these disks is dominated by optically thick dust thermal emission, independent of $F_{250\,\mathrm{GHz}}$ and $R_{95\%}$. As a result, the (sub)millimeter luminosity and the apparent disk size are positively correlated, which has been found in numerous resolved emission surveys of Class II disks. In young clusters with ages of $\sim$1-2 Myr, Class II disks with smaller radii or lower (sub)millimeter luminosities are not necessarily those in which the dust mass budget has been consumed or dispersed.
