The circumstellar disc in the Bok globule CB 26: Multi-wavelength observations and modelling of the dust disc and envelope
J. Sauter, S. Wolf, R. Launhardt, D. L. Padgett, K. R. Stapelfeldt, C. Pinte, G. Duchene, F. Menard, C. -E. McCabe, K. Pontoppidan, M. Dunham, T. -L. Bourke, J. -H. Chen
备注：
18 pages, 15 figures, Accepted for publication in A&A
Circumstellar discs are expected to be the nursery of planets. Grain growth within such discs is the first step in the planet formation process. The Bok globule CB 26 harbours such a young disc. We present a detailed model of the edge-on circumstellar disc and its envelope in the Bok globule CB 26. The model is based on HST near-infrared maps in the I, J, H, and K bands, OVRO and SMA radio maps at 1.1mm, 1.3mm and 2.7mm, and the spectral energy distribution (SED) from 0.9 microns to 3mm. New photometric and spectroscopic data from the Spitzer Space Telescope and the Caltech Submilimeter Observatory have been obtained and are part of our analysis. Using the self-consistent radiative transfer code MC3D, the model we construct is able to discriminate parameter sets and dust properties of both its parts, namely envelope and disc. We find that the disc has an inner hole with a radius of 45 +/- 5 AU. Based on a dust model including silicate and graphite the maximum grain size needed to reproduce the spectral millimetre index is 2.5 microns. Features seen in the near-infrared images, dominated by scattered light, can be described as a result of a rotating envelope. Successful employment of ISM dust in both the disc and envelope hint that grain growth may not yet play a significant role for the appearance of this system. A larger inner hole gives rise to the assumption that CB 26 is a circumbinary disc.
Bok globule CB17: Polarization, extinction and distance
本文介绍了博克球CB 17在光波和亚毫米波段的偏振研究结果。2016年3月9日，在印度奈尼塔尔ARIES的1.04米Sampurnanand望远镜上进行了R波段（$λ$ = 630 nm，$Δλ$ = 120 nm）的光学偏振观测，而亚毫米偏振数据来自SCUPOL数据档案，该档案已被重新分析。Herschel \footnote{Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.} SPIRE 500 $μm$尘埃连续辐射CB 17的轮廓（典型的彗星状球状体）与偏振矢量（光学和亚毫米）一起叠加在CB 17的DSS图像上。球核处的磁场强度估计为$99μ$ G。利用近红外测光技术和\emph{Gaia}数据，发现到CB 17的距离为$253 \pm 43$秒差距。还研究了小球的各种数量之间的相关性。据观察，磁场在云核中所揭示的偏振测量在亚毫米尘埃排放被发现几乎是沿着短轴的球状体，这符合磁调节恒星形成模型。同时还发现了核尺度磁场方向与分子流出方向的错位。
