Galactic Cold Interstellar Filaments: Structure, Kinematics, and Chemistry

点击翻译按钮获取中文摘要

Molecular interstellar medium is known to be highly hierarchical and filamentary. Studies in recent years have demonstrated the importance of filaments in star formation, at scales of <10 pc and >100 pc, and suggest a new paradigm for star formation. However, extremely filamentary giant molecular clouds (GMCs) at scales between 10 and 100 pc have not been studied systematically. A compelling sample does not exist at the first place, due to a historical limitation in the identifying methodology (i.e., extinction). In this project, we use the full Hi-GAL images to directly search for large filaments in the entire Galactic plane. We select a sample of 9 most prominent filaments with a length of 30-103 pc and mass (2.4-19)x10^4 Msun. The filaments are cold compared to surroundings and show no significant internal heating. This makes our project unique in probing the early evolutionary phases to study the connection of filamentary GMCs to the onset of star formation. We propose to perform a first systematic characterization of these filaments focusing on their hierarchical structure, kinematics, and core chemistry, aiming to reveal a comprehensive picture of high-mass star formation in the context of large filaments. The methods are designed so that results are directly comparable to numerical simulations and theoretical predictions. This is a timely project making use of the newly available Hi-GAL data, and will fill the gap between Galactic and local filaments, towards an understanding of filaments at all spatial scales.