The radiation from stars and active galactic nuclei (AGNs) creates photodissociation regions
(PDRs) and X-ray-dominated regions (XDRs), where the chemistry or heating is dominated …

CO line emission represents the most accessible and widely used tracer of the molecular
ISM. This renders the translation of observed CO intensity into total H2 gas mass critical to …

A new collection of photodissociation and photoionisation cross sections for 102 atoms and
molecules of astrochemical interest has been assembled, along with a brief review of the …

The James Webb Space Telescope (JWST, Gardner et al. 2006) is a 6.5 m space telescope
launched in 2021 December and is developed by the National Aeronautics and Space …

Large polycyclic aromatic hydrocarbon (PAH) molecules carry the infrared (IR) emission
features that dominate the spectra of most galactic and extragalactic sources. This review …

Star formation lies at the center of a web of processes that drive cosmic evolution:
generation of radiant energy, synthesis of elements, formation of planets, and development …

The mass of molecular gas in an interstellar cloud is often measured using line emission
from low rotational levels of CO, which are sensitive to the CO mass, and then scaling to the …

Water is a fundamental molecule in the universe. On Earth, water exists in all three phases:
gas, liquid, and solid (ice). Liquid water facilitates many chemical reactions as a solvent …

Much of the interstellar medium in disk galaxies is in the form of neutral atomic hydrogen, H
I. This gas can be in thermal equilibrium at relatively low temperatures, T≲ 300 K (the cold …

The interstellar medium of galaxies is the reservoir out of which stars are born and into
which stars inject newly created elements as they age. The physical properties of the …