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arXiv 1003.3193astro-ph.SR
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红外暗云中恒星形成的早期阶段：表征核心尘埃的性质

The early stages of star formation in Infrared Dark Clouds: characterizing the core dust properties

J. M. Rathborne, J. M. Jackson, E. T. Chambers, I. Stojimirovic, R. Simon, R. Shipman, W. Frieswijk

备注：
Accepted by ApJ. 107 pages in total (72 pages of on-line only material).
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摘要：

红外暗云（IRDC）被认为是明亮的银河系中红外背景下的消光特征，被认为是恒星和团簇形成的最早阶段。为了更好地表征其嵌入芯的性质，我们获得了38个IRDC样品的新的24 μ m，60- 100 μ m和亚毫米连续谱数据。24微米的斯皮策图像显示，虽然IRDC仍然是黑暗的，但许多核心与明亮的24微米发射源有关，这表明它们包含一个或多个嵌入的原恒星。结合24微米，60- 100微米，和亚毫米连续数据，我们已经构建了宽带光谱能量分布（SED）的157个核心在这些IRDC和，使用简单的灰体拟合的SED，估计他们的尘埃温度，发射率，不透明度，辐射光度，质量和密度。基于他们的斯皮策/IRAC 3- 8微米的颜色和24微米的点源发射的存在，我们已经分离出的核心，港口活跃，高质量的恒星形成的核心是静止的。活跃的“原恒星”核心通常比较为静止的、也许是“前原恒星”的核心具有更高的尘埃温度和更高的辐射热光度。由于人口的质量分布是相似的，但是，我们推测，活动和静止的核心可能代表不同的进化阶段的核心相同的底层人口。虽然我们不能排除在静止的核心中形成低质量的恒星，但其中质量最大的是“高质量无星核心”阶段的绝佳候选者，这是高质量恒星形成的最早阶段。

英文摘要：

Identified as extinction features against the bright Galactic mid-infrared background, infrared dark clouds (IRDCs) are thought to harbor the very earliest stages of star and cluster formation. In order to better characterize the properties of their embedded cores, we have obtained new 24um, 60-100um, and sub-millimeter continuum data toward a sample of 38 IRDCs. The 24um Spitzer images reveal that while the IRDCs remain dark, many of the cores are associated with bright 24um emission sources, which suggests that they contain one or more embedded protostars. Combining the 24um, 60-100um, and sub-millimeter continuum data, we have constructed broadband spectral energy distributions (SEDs) for 157 of the cores within these IRDCs and, using simple gray-body fits to the SEDs, have estimated their dust temperatures, emissivities, opacities, bolometric luminosities, masses and densities. Based on their Spitzer/IRAC 3-8um colors and the presence of 24um point source emission, we have separated cores that harbor active, high-mass star formation from cores that are quiescent. The active `protostellar' cores typically have warmer dust temperatures and higher bolometric luminosities than the more quiescent, perhaps `pre-protostellar', cores. Because the mass distributions of the populations are similar, however, we speculate that the active and quiescent cores may represent different evolutionary stages of the same underlying population of cores. Although we cannot rule out low-mass star-formation in the quiescent cores, the most massive of them are excellent candidates for the `high-mass starless core' phase, the very earliest in the formation of a high-mass star.

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