Submillimetre observations and modelling of Vega-type stars
Submillimetre observations and modelling of Vega-type stars
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织女星型恒星的亚毫米观测和建模
DOI：
10.1111/j.1365-2966.2004.07448.x
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发表时间：
2003
影响因子：
4.8
通讯作者：
M. Wyatt
中科院分区：
文献类型：
--
作者：
I. Sheret;W. Dent;M. Wyatt
我们提出了新的亚毫米观测的织女星多余的恒星，和一致的建模与亚毫米数据的所有已知的织女星多余的恒星。我们的分析使用具有现实光学特性的尘埃颗粒模型，目的是从光谱能量分布（SED）中确定未解析光盘的物理参数。对于解决的目标，我们发现，不同的对象需要非常不同的尘埃颗粒的属性，以适应图像数据和SED同时。北落师门和织女星需要固体尘埃颗粒，而HR 4796和HD 141569只能使用多孔颗粒。较老的恒星往往比较年轻的恒星具有更少孔隙的颗粒，这可能表明圆盘中的碰撞已经将最初蓬松的颗粒重新加工成更坚固的形式。e与我们的最佳拟合模型相比，Eri似乎缺乏小尘埃颗粒。这可能表明，对于接近辐射压力吹出极限的颗粒，包括导致粒度分布偏离简单幂律的所有因素是重要的。或者，这种差异可能是由于圆盘上的一些外部影响（例如行星）。
当该模型应用于未分辨的目标时，可以对光盘大小进行估计。然而，大的差异，尘埃成分的解决光盘意味着，我们不能作出可靠的假设，在一个未解决的光盘的颗粒的组成，并有相应的不确定性，光盘的大小。此外，对e Eri的拟合不佳表明，即使已知光盘大小，该模型也不能始终考虑SED。这两个因素意味着，如果不实际解决它，就不可能确定光盘的大小。
We present new submillimetre observations of Vega-excess stars, and consistent modelling for all known Vega-excess stars with submillimetre data. Our analysis uses dust grain models with realistic optical properties, with the aim of determining physical parameters of the unresolved discs from just their spectral energy distributions (SEDs). For the resolved targets, we find that different objects require very different dust grain properties in order to fit the image data and SED simultaneously. Fomalhaut and Vega require solid dust grains, while HR 4796 and HD 141569 can only be fitted using porous grains. The older stars tend to have grains which are less porous than the younger stars, which may indicate that collisions in the discs have reprocessed the initially fluffy grains into a more solid form. e Eri appears to be deficient in small dust grains compared with our best-fitting model. This may show that it is important to include all the factors that cause the size distribution to depart from a simple power law for grains close to the radiation pressure blow-out limit. Alternatively, this discrepancy may be due to some external influence on the disc (e.g. a planet).
When the model is applied to the unresolved targets, an estimate of the disc size can be made. However, the large diversity in dust composition for the resolved discs means that we cannot make a reliable assumption as to the composition of the grains in an unresolved disc, and there is corresponding uncertainty in the disc size. In addition, the poor fit for e Eri shows that the model cannot always account for the SED even if the disc size is known. These two factors mean that it may not be possible to determine the size of a disc without actually resolving it.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell