1.3 mm ALMA Observations of the Fomalhaut Debris System
1.3 mm ALMA Observations of the Fomalhaut Debris System
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1.3 毫米 ALMA 对北落师门碎片系统的观测
DOI：
10.1093/mnras/stw3303
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发表时间：
2016
影响因子：
4.8
通讯作者：
S. Corder
中科院分区：
文献类型：
--
作者：
J. White;A. Boley;W. Dent;E. Ford;S. Corder
我们提出的阿尔马波段6观测（1.3毫米/233千兆赫）的北落师门和它的碎片盘。观测的灵敏度为17 μ Jy，分辨率为0.28角秒（在7.66 pc的距离上为2.1 Au），这是迄今为止对北落师门主碎片环中毫米颗粒的最高分辨率观测。该环被严格约束为139 ^{+2}_{-3}$ Au，半高宽为13 μ m3 $ Au，遵循高斯分布。毫米光谱指数被限制为$\alpha_{mm} =-2.62\pm0.12$。我们探索在图像平面中拟合碎片盘模型，以及直接使用可见性数据拟合模型。结果进行了比较，并讨论了每种方法的潜在优点/缺点。
检测到的中心排放是无法区分的点源，最可能的通量为0.90\pm 0.12$ mJy（包括校准不确定性）。这意味着，正如从远红外观测中推断的那样，任何内部碎片结构对总中心发射的贡献一定很小。此外，恒星通量小于70%的预测，由约束恒星光球温度外推一个黑体。这一结果强调，在正确理解宿主星星在毫米波长下的固有恒星发射行为之前，无法充分确定未解决的内部碎片成分的特征。
We present ALMA Band 6 observations (1.3 mm/233 GHz) of Fomalhaut and its debris disc. The observations achieve a sensitivity of 17 $\mu$Jy and a resolution of 0.28 arcsec (2.1 au at a distance of 7.66 pc), which are the highest resolution observations to date of the millimetre grains in Fomalhaut's main debris ring. The ring is tightly constrained to $139^{+2}_{-3}$ au with a FWHM of $13\pm3$ au, following a Gaussian profile. The millimetre spectral index is constrained to $\alpha_{mm} = -2.62\pm0.12$. We explore fitting debris disc models in the image plane, as well as fitting models using visibility data directly. The results are compared and the potential advantages/disadvantages of each approach are discussed.
The detected central emission is indistinguishable from a point source, with a most probable flux of $0.90\pm 0.12$ mJy (including calibration uncertainties). This implies that any inner debris structure, as was inferred from far-Infrared observations, must contribute little to the total central emission. Moreover, the stellar flux is less than 70\% of that predicted by extrapolating a black body from the constrained stellar photosphere temperature. This result emphasizes that unresolved inner debris components cannot be fully characterized until the behaviour of the host star's intrinsic stellar emission at millimetre wavelengths is properly understood.