Generation and Evolution of Structures in the interstellar medium

恒星的形成与星际介质(ISM)中分子云的结构和演化密切相关。我们建议用一种新的方法来探索这种联系，将尘埃(Herschel)和冷却线(C+与Sofia)的远红外图与分子线图结合起来。将使用和开发专门的分析工具来分析地图，并将其与模拟进行比较，以便确定基本的物理过程。这一联合项目依赖于科隆科斯马小组(结构鉴定方法和索非亚)、波尔多实验室恒星形成小组(赫歇尔和光谱成像图)和研究所波尔多大地统计小组(复杂系统分析的非线性方法专家)成员的互补专门知识。为了了解恒星的起源，有必要弄清重力、湍流、磁场和辐射在扩散气体、分子云和坍塌核心中的相对重要性，并研究细丝的作用。使用Geostat团队开发的创新分析工具，我们将使用SOFIA分析赫歇尔图像以及来自地面望远镜的新光谱成像调查和太赫兹光谱分析。与对模拟云的类似分析相比较，我们可以得到解释云演化和致密结构形成的潜在物理过程。我们选择覆盖质量、温度和恒星形成活动的典型参数空间的模板云来测试恒星形成云的不同演化阶段和多样性。需要与科隆小组密切合作，才能从波尔多合作伙伴(实验室)将与Geostat共同开发的这些创新方法和分析工具的量化云结构(例如，增量方差)和统计测量(例如，N-PDF)方面的长期专业知识中获益。我们还将探索湍流与加热和冷却过程的耦合，这将导致结构变化，这可能有助于我们更好地理解反馈在调节恒星形成效率方面的作用。更准确地说，我们的目标是确定从原子到分子氢的过渡相的空间尺度，确定湍流消散的位置，并深入了解其他结构生成过程。该项目的目标不是在3年内充分了解恒星的形成，但它是向前迈出的重要一步，因为它将系统地利用大量现有的、尚未充分利用的档案数据、精心选择的新观测以及分析和解释数据的复杂工具。因此，它将为分子云和恒星的形成提供新的线索，并很可能成为后续许多研究的起点。

The formation of stars is intimately linked to the structure and evolution of molecular clouds in the interstellar medium (ISM). We propose to explore this link with a new approach by combining far-infrared maps of dust (Herschel) and cooling lines (C+ with SOFIA) with molecular line maps. Dedicated analysis tools will be used and developed to analyse the maps and compare them to simulations in order to identify for the underlying physical processes. This joint project relies on the complementary expertise of the members of the Cologne KOSMA group (structure identification methods and SOFIA), the Bordeaux LAB star formation group (Herschel and spectro-imaging maps) , and the Bordeaux GeoStat team of INRIA institute (experts in nonlinear methods for the analysis of complex systems). To understand the genesis of stars, it is necessary to disentangle the relative importance of gravity, turbulence, magnetic fields, and radiation from diffuse gas, to molecular clouds and collapsing cores, and to study the role of filaments. Using innovative new analysing tools developed by the GeoStat team, we will analyse the Herschel images as well as new spectro-imaging surveys from ground-based telescopes, and THz spectroscopy using SOFIA. The comparison with similar analysis on simulated clouds will allow us to derive the underlying physical process which explains cloud evolution and the formation of dense structures. We select template clouds that cover a representative parameter space of mass, temperature, and star-formation activity to test the different evolutionary stages and the diversity in star-forming clouds. Close collaboration with the Cologne group is required to profit from their long-lasting expertise of quantifying cloud structure (e.g. Delta-variance) and statistical measures (e.g. N-PDFs) for these innovative methods and analysis tools that will be developed by the Bordeaux partner (LAB) in an interdisciplinary effort together with GeoStat. We will also explore the coupling of turbulence with heating- and cooling processes that leads to structural changes and that may help us to improve our understanding of the role of feedbacks to regulate the star formation efficiency. More precisely we aim at identifying the spatial scales of the transition phase from atomic to molecular hydrogen, at determining the location of the dissipation of turbulence and get insight into other structure generating processes. The project does not aim at a full understanding of star formation within 3 years, but it constitutes an important step forward as it will make systematic use of a wealth of existing, yet not fully exploited archival data, carefully chosen new observations, and sophisticated tools to analyse and interpret the data. As such, it will shed new light on how molecular clouds and stars form and may well be the starting point for many studies to follow.