We present optical and submillimetre polarimetry data of the Bok globule CB3 and optical polarimetry data of the Bok globule CB246. We use each set of polarimetry data to infer the B-field orientation in each of the clouds. The optical data can only be used in the low density, low extinction edge regions of clouds. The submillimetre data can only be used in the high column-density, central regions of the clouds.
It has previously been found that near-infrared polarisation mapping of background stars does not accurately trace the magnetic field in dense cloud regions. This may be due to a lack of aligned grains in dense regions. We test this by comparing the field orientations measured by our two independent polarimetry methods. We find that the field orientation deduced from the optical data matches up well with the orientation estimated from the submillimetre data. We therefore claim that both methods are accurately tracing the same magnetic field in CB3. Hence, in this case, there must be significant numbers of aligned dust grains in the high density region, and they do indeed trace the magnetic field in the submillimetre.
We find an offset of 40$\pm$14 degrees between the magnetic field orientation and the short axis of the globule. This is consistent with the mean value of 31$\pm$3 degrees found in our previous work on prestellar cores, even though CB3 is a protostellar core. Taken together, the six prestellar cores that we have now studied in this way show a mean offset between magnetic field orientation and core short axis of $\sim30\pm$3 degrees, in apparent contradiction with some models of magnetically dominated star formation.
A Survey of Magnetic Field Properties in Bok Globules
Indian Institute of Technology Bombay（印度理工学院孟买分校）；Massachusetts Institute of Technology（麻省理工学院）；Instituto Nacional de Pesquisas Espaciais (INPE/MCTI)（国家空间研究所）；Leiden University（莱顿大学）；SKA Observatory（平方公里阵列射电望远镜天文台）；National Radio Astronomy Observatory（美国国家无线电天文台）
Bok globule CB17: Polarization, extinction and distance
本文介绍了博克球CB 17在光波和亚毫米波段的偏振研究结果。2016年3月9日，在印度奈尼塔尔ARIES的1.04米Sampurnanand望远镜上进行了R波段（$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。
