Neutral hydrogen filaments in interstellar media: Are they physical?
Review article, 2024

The trending term “filament” is extensively used in the interstellar medium (ISM) and the star formation community, and is believed to be one of the most important objects that gauge molecular cloud and star formation. However, the physical definition of these ubiquitous, elongated, high contrast features is poorly defined and still actively debated. Despite the absence of a unified consensus, filaments are believed to be involved in many important physical processes from galaxy structure formation to the emergence of protostellar objects. Therefore, understanding how filaments form, what constrains their growth, and their general physical properties, are extremely important for theorists and observers who study the dynamics of the ISM and consequent star formations. This review serves as a collection of the community’s views and develops the concept of “filaments” in the context of the ISM and star-forming clouds. Observationally, filaments are seen across the entire sky and often carry an aspect ratio of the order of hundreds. In the context of the ISM, filaments are believed to form by stretching and tearing from magnetized ISM turbulence. ISM filaments are subjected to heating and cooling phases, and are likely to be magnetically aligned. Cold clouds are formed inside ISM due to turbulence instability. This review updates the understanding of ISM filaments in the community.

Filaments

Turbulence

Star formation

Interstellar media

Magnetic field

Author

Ka Ho Yuen

Los Alamos National Laboratory

Ka Wai Ho

University of Wisconsin Madison

Los Alamos National Laboratory

Chi Yan Law

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Arcetri Astrophysical Observatory

Avi Chen

Rutgers University

Reviews of Modern Plasma Physics

23673192 (eISSN)

Vol. 8 1 21

Subject Categories

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

Fusion, Plasma and Space Physics

DOI

10.1007/s41614-024-00156-5

More information

Latest update

5/23/2024