The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A
The JCMT Gould Belt Survey: the effect of molecular contamination in SCUBA-2 observations of Orion A
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DOI：
10.1093/mnras/stv3009
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发表时间：
2016-01
影响因子：
4.8
通讯作者：
S. Coudé;P. Bastien;H. Kirk;D. Johnstone;E. Drabek-Maunder;S. Graves;J. Hatchell;EL Chapin
中科院分区：
文献类型：
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作者：
S. Coudé;P. Bastien;H. Kirk;D. Johnstone;E. Drabek-Maunder;S. Graves;J. Hatchell;EL Chapin
巨分子云中冷尘埃颗粒的热辐射可以用来探测恒星形成区的密度、温度和发射率等物理性质。本文介绍了詹姆斯·克拉克麦克斯韦望远镜（JCMT）在猎户座A分子云复合体450和850 μm处的亚毫米普通用户测辐射热仪阵列（SCUBA-2）共享风险观测。以往的研究表明，分子发射线可以在这些连续带的测量通量显着的贡献。我们使用外差阵列接收器计划12 CO J = 3−2猎户座A的积分强度图，以评估分子线污染及其对SCUBA-2图的影响。利用修正后的通量，我们得到了一个新的积分形暗条中尘埃热辐射的光谱指数α图。此外，我们比较了33个来源的样本，选择了猎户座A分子云复合体的高12 CO J = 3−2线污染，与OMC 4中先前确定的27个团块。这使我们能够量化谱线污染对850-450 μm通量密度比值的影响，以及它如何修改尘埃颗粒的发射率β的推导光谱指数。我们还发现OMC 5中至少有一个斯皮策确定的原恒星核心具有16%的12 CO J = 3−2污染水平。此外，我们发现OMC 2附近的年轻星星具有最强的污染水平（44%）。这项工作是JCMT古尔德带遗产调查的一部分。
Thermal emission from cold dust grains in giant molecular clouds can be used to probe the physical properties, such as density, temperature and emissivity in star-forming regions. We present the Submillimetre Common-User Bolometer Array (SCUBA-2) shared-risk observations at 450 and 850 μm of the Orion A molecular cloud complex taken at the James Clerk Maxwell Telescope (JCMT). Previous studies showed that molecular emission lines can contribute significantly to the measured fluxes in those continuum bands. We use the Heterodyne Array Receiver Programme 12CO J = 3−2 integrated intensity map for Orion A in order to evaluate the molecular line contamination and its effects on the SCUBA-2 maps. With the corrected fluxes, we have obtained a new spectral index α map for the thermal emission of dust in the well-known integral-shaped filament. Furthermore, we compare a sample of 33 sources, selected over the Orion A molecular cloud complex for their high 12CO J = 3−2 line contamination, to 27 previously identified clumps in OMC 4. This allows us to quantify the effect of line contamination on the ratio of 850–450 μm flux densities and how it modifies the deduced spectral index of emissivity β for the dust grains. We also show that at least one Spitzer-identified protostellar core in OMC 5 has a 12CO J = 3−2 contamination level of 16 per cent. Furthermore, we find the strongest contamination level (44 per cent) towards a young star with disc near OMC 2. This work is part of the JCMT Gould Belt Legacy Survey.