Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A Grid of 200,000 YSO Model SEDs
Interpreting Spectral Energy Distributions from Young Stellar Objects. I. A Grid of 200,000 YSO Model SEDs
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DOI：
10.1086/508424
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发表时间：
2006-08
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影响因子：
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通讯作者：
T. Robitaille;B. Whitney;R. Indebetouw;K. Wood;P. Denzmore
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文献类型：
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作者：
T. Robitaille;B. Whitney;R. Indebetouw;K. Wood;P. Denzmore
我们提出了一个网格的辐射传输模型的轴对称的年轻恒星物体（YSO），涵盖了广泛的恒星质量（从0.1到50 M的反射）和演化阶段（从早期的信封下降阶段的后期磁盘只有阶段）。该网格由20，000个YSO模型组成，每个模型在10个视角下计算光谱能量分布（SED）和偏振光谱，总共产生200，000个SED。我们已经仔细评估了理论和观测的限制，在YSO的磁盘和信封的物理条件，并试图完全跨越参数空间中的相应区域。这些模型在专用的Web服务器上公开提供。在本文中，我们总结了我们的模型的主要特点，以及探索的参数范围。拥有一个覆盖参数空间合理区域的大网格，使我们能够揭示YSO近红外和中红外观测的许多趋势（例如光谱指数和SED颜色的变化），将它们与物理参数（例如磁盘和下落包络参数）联系起来。特别是，我们研究的依赖性的包络吸积率和磁盘质量的模型SED的光谱指数。此外，我们显示的光谱指数与恒星温度，磁盘内半径，和磁盘耀斑功率的一个子集的磁盘模型的变化。我们还研究了如何改变用于计算光谱指数的数据的波长范围影响其值。我们显示了整个网格的样本颜色-颜色图以及具有典型斯皮策灵敏度的不同距离处的模拟集群。我们发现，年轻的嵌入源一般占据了一个大区域的颜色颜色空间，由于倾斜和恒星温度的影响。盘源占据一个较小的区域的颜色-颜色空间，但基本上与嵌入式源所占据的区域重叠，特别是在近红外和中红外。我们确定的颜色-颜色空间中的区域，我们的模型表明，只有在一个给定的进化阶段的源应该说谎。我们发现，虽然近红外（如JHK）和中红外（如IRAC）通量有助于区分恒星和YSO，并有助于识别非常年轻的源，但增加更长波长的数据，如MIPS 24 μm，对于确定YSO的演化阶段非常有价值。
We present a grid of radiation transfer models of axisymmetric young stellar objects (YSOs), covering a wide range of stellar masses (from 0.1 to 50 M☉) and evolutionary stages (from the early envelope infall stage to the late disk-only stage). The grid consists of 20,000 YSO models, with spectral energy distributions (SEDs) and polarization spectra computed at 10 viewing angles for each model, resulting in a total of 200,000 SEDs. We have made a careful assessment of the theoretical and observational constraints on the physical conditions of disks and envelopes in YSOs and have attempted to fully span the corresponding regions in parameter space. These models are publicly available on a dedicated Web server. In this paper we summarize the main features of our models, as well as the range of parameters explored. Having a large grid covering reasonable regions of parameter space allows us to shed light on many trends in near- and mid-IR observations of YSOs (such as changes in the spectral indices and colors of their SEDs), linking them with physical parameters (such as disk and infalling envelope parameters). In particular, we examine the dependence of the spectral indices of the model SEDs on envelope accretion rate and disk mass. In addition, we show variations of spectral indices with stellar temperature, disk inner radius, and disk flaring power for a subset of disk-only models. We also examine how changing the wavelength range of data used to calculate spectral indices affects their values. We show sample color-color plots of the entire grid as well as simulated clusters at various distances with typical Spitzer sensitivities. We find that young embedded sources generally occupy a large region of color-color space due to inclination and stellar temperature effects. Disk sources occupy a smaller region of color-color space but overlap substantially with the region occupied by embedded sources, especially in the near- and mid-IR. We identify regions in color-color space where our models indicate that only sources at a given evolutionary stage should lie. We find that, while near-IR (such as JHK) and mid-IR (such as IRAC) fluxes are useful in discriminating between stars and YSOs, and are useful for identifying very young sources, the addition of longer wavelength data such as MIPS 24 μm is extremely valuable for determining the evolutionary stage of YSOs.