BISTRO (B-Fields in Star-Forming Region Observations) JCMT Large Programme: First observing run

BISTRO（恒星形成区观测中的 B 场）JCMT 大型计划：首次观测运行

• 批准号: ST/P00119X/1
• 负责人: Derek Ward-Thompson
• 金额: $ 0.26万
• 依托单位: University of Central Lancashire
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FP00119X%2F1
• 关键词: BISTRO; Fields; Star; Forming; Region

We will use POL-2 to map the polarization in the densest parts of all of the Gould Belt star-forming regions that we have previously mapped with SCUBA-2 and HARP-B, in order to trace (via the Chandrasekhar-Fermi method) the magnetic field direction and strength in the centres of all of these regions. This will answer currently open questions in star formation, such as the relative importance of magnetic fields and turbulence to star formation, and will allow us to test current models of star formation, such as the Herschel model of magnetic funnelling onto filaments.POL-2 with SCUBA-2 on JCMT is a unique facility, as it is the only facility world-wide that can map the magnetic field within cold dense cores and filaments on scales of ~1000 AU in nearby star-forming regions, such as Taurus and Ophiuchus. This size scale is crucial for testing models such as the filamentary star formation model, because we know from other studies that the large-scale field lies roughly perpendicular to the overall typical filament directions, but we do not know what happens to the field within the dense gas of the filaments themselves, nor what happens within the cores that form in the filaments. This is crucial to understanding the physical processes taking place, and to discriminating between the models of the star formation process that properly incorporate magnetic fields. The current hypotheses are either that the field may wrap around the filament in a helical manner, or else turn to run parallel to the filament in the densest gas. We will be able to distinguish between these two scenarios.There is debate about the role that the B-field plays in shaping proto-stellar evolution once proto-stars have formed and its effect on bipolar outflows. For example, recent studies find no correlation between outflow and magnetic field directions on scales less than 1000 AU, while there is correlation on scales of ~10,000 AU and above. One explanation of this apparent conflict in the field morphology uses detailed modelling of toroidally wrapped B-fields at the centres of clouds. This has been used to explain early disk formation in Class 0 proto-stars in a recent model in which early disks are hypothesized to be formed preferentially in fields misaligned with the outflow directions. The legacy value of this large-scale homogeneous data-set will be huge. All future models of the role of magnetic fields in star formation will be forced to explain these observations in all of the nearest star-forming regions.

我们将使用POL-2在所有这些区域的磁场方向和强度。这将回答当前在星形形成中的开放问题，例如磁场和湍流对星形形成的相对重要性，并使我们能够测试当前的恒星形成模型，例如herschel磁性漏斗的herschel磁性模型。恒星形成区域，例如金牛座和奥菲古斯。这种尺寸尺度对于测试模型（例如丝状恒星形成模型）至关重要，因为我们从其他研究中知道，大规模场与整体典型的灯丝方向大致垂直于垂直于整体典型的灯丝方向，但是我们不知道丝源本身的密集气体内发生了什么事，也不知道在纤维中形成的核心中发生了什么。这对于理解发生的物理过程以及区分正确包含磁场的恒星形成过程的模型至关重要。当前的假设是，该场可以以螺旋的方式包裹灯丝，或者转弯以平行于最密集的气体中的细丝。我们将能够区分这两种情况。关于B场在原始明星形成及其对双极外流的影响后，存在关于B场在塑造原始恒星演化中所扮演的作用的争论。例如，最近的研究发现尺度小于1000 AU的流出和磁场方向之间没有相关性，而尺度上的相关性约为10,000 au及以上。对田间形态中这种明显冲突的一种解释使用了云中心的环形包裹的B场的详细建模。在最近的一个模型中，这被用来解释0类Proto-Star中的早期磁盘形成，其中假设早期磁盘在与流出方向未对准的田地中优先形成。这个大规模同质数据集的遗产价值将是巨大的。磁场在恒星形成中的作用的所有未来模型将被迫解释所有最近的恒星形成区域中的这些观察结果。