Earliest phases of star formation (EPoS). Dust temperature distributions in isolated starless cores
Earliest phases of star formation (EPoS). Dust temperature distributions in isolated starless cores
复制标题
恒星形成的最早阶段（EPoS）。
DOI：
--
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
A. Schmiedeke
中科院分区：
文献类型：
--
作者：
N. Lippok;R. Launhardt;T. Henning;Z. Balog;H. Beuther;J. Kainulainen;O. Krause;H. Linz;M. Nielbock;S. Ragan;S. Ragan;Thomas Robitaille;S. Sadavoy;A. Schmiedeke;A. Schmiedeke
上下文恒星的形成是由寒冷而致密的分子云核心的引力坍缩造成的。限制这种核心的温度和密度结构是理解星星形成的初始条件的基础。我们使用赫歇尔观测的热远红外（FIR）尘埃排放附近和孤立的分子云核心和联合收割机结合他们与地面的亚毫米波连续数据，以获得其温度和密度结构的观测约束。
目的：本研究的目的是验证射线追踪反演技术的有效性，该技术用于直接从尘埃排放图中导出附近和孤立的无星核的尘埃温度和密度结构，并测试所得到的温度和密度分布是否与物理模型一致。
研究方法：我们已经开发了一种射线跟踪反演技术，可以用来直接从观测到的尘埃排放图推导出无星核的温度和密度结构，而不需要对物理条件进行假设。利用这种射线追踪反演技术，我们从100 μm-1.2 mm波段的尘埃辐射图中得到了6个孤立的无星分子云核的尘埃温度和密度结构，然后对射线追踪反演得到的密度分布进行了自洽辐射传输模拟。在该模型中，星际辐射场（ISRF）是唯一的热源。ISRF的局部强度以及由外壳提供的总消光被视为半自由参数，我们在定义的范围内缩放。这两个参数的最佳拟合值来自通过比较自洽计算的温度分布与射线追踪法得到的。
结果如下：我们证实了早期的结果，并表明，所有的无星核心是显着冷内部比外部，与中心核心温度在7.5-11.9 K和信封的温度是2.4 - 9.6 K高。核心温度显示出很强的负相关性与峰值柱密度，这表明核心的热结构是由来自ISRF的外部加热和屏蔽的灰尘信封。我们发现，用射线追踪反演方法得到的温度剖面可以很好地用自适应方法再现。一致的辐射传输模型，如果核心的几何结构不是太复杂，并且具有良好的数据覆盖率，空间分辨地图在100 μm和1.2 mm之间的五个或更多波长。我们还证实了早期研究的结果，这些研究发现，通常采用的总强度的典型值ISRF在太阳附近的不透明度模型与最广泛使用的致密核心尘埃不透明度模型不相容。然而，本研究的数据，我们不能唯一地解决尘埃不透明度的法律和ISRF的强度之间的简并。
Context. Stars form by the gravitational collapse of cold and dense molecular cloud cores. Constraining the temperature and density structure of such cores is fundamental for understanding the initial conditions of star formation. We use Herschel observations of the thermal far-infrared (FIR) dust emission from nearby and isolated molecular cloud cores and combine them with ground-based submillimeter continuum data to derive observational constraints on their temperature and density structure.
Aims: The aim of this study is to verify the validity of a ray-tracing inversion technique developed to derive the dust temperature and density structure of nearby and isolated starless cores directly from the dust emission maps and to test if the resulting temperature and density profiles are consistent with physical models.
Methods: We have developed a ray-tracing inversion technique that can be used to derive the temperature and density structure of starless cores directly from the observed dust emission maps without the need to make assumptions about the physical conditions. Using this ray-tracing inversion technique, we derive the dust temperature and density structure of six isolated starless molecular cloud cores from dust emission maps in the wavelengths range 100 μm-1.2 mm. We then employ self-consistent radiative transfer modeling to the density profiles derived with the ray-tracing inversion method. In this model, the interstellar radiation field (ISRF) is the only heating source. The local strength of the ISRF as well as the total extinction provided by the outer envelope are treated as semi-free parameters which we scale within defined limits. The best-fit values of both parameters are derived by comparing the self-consistently calculated temperature profiles with those derived by the ray-tracing method.
Results: We confirm earlier results and show that all starless cores are significantly colder inside than outside, with central core temperatures in the range 7.5-11.9 K and envelope temperatures that are 2.4 - 9.6 K higher. The core temperatures show a strong negative correlation with peak column density which suggests that the thermal structure of the cores is dominated by external heating from the ISRF and shielding by dusty envelopes. We find that temperature profiles derived with the ray-tracing inversion method can be well-reproduced with self-consistent radiative transfer models if the cores have geometry that is not too complex and good data coverage with spatially resolved maps at five or more wavelengths in range between 100 μm and 1.2 mm. We also confirm results from earlier studies that found that the usually adopted canonical value of the total strength of the ISRF in the solar neighbourhood is incompatible with the most widely used dust opacity models for dense cores. However, with the data available for this study, we cannot uniquely resolve the degeneracy between dust opacity law and strength of the ISRF.
DOI：
10.1088/0067-0049/188/1/139
发表时间：
2010-04
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
R. Launhardt;D. Nutter;D. Ward-Thompson;T. Bourke;T. Henning;T. Khanzadyan;T. Khanzadyan;M. Schmalzl;S. Wolf;S. Wolf;R. Zylka
通讯作者：
R. Launhardt;D. Nutter;D. Ward-Thompson;T. Bourke;T. Henning;T. Khanzadyan;T. Khanzadyan;M. Schmalzl;S. Wolf;S. Wolf;R. Zylka