## Heiles et al. (2019) – The interstellar medium: the key component in galactic evolution and modern cosmology

The gases of the interstellar medium (ISM) possess orders of magnitude more mass than those of all the stars combined and are thus the prime component of the baryonic Universe.

## Murray et al. (2018) – Optically Thick H I Does Not Dominate Dark Gas in the Local ISM

The local interstellar medium (ISM) is suffused with “dark” gas, identified by excess infrared and gamma-ray emission, yet undetected by standard ISM tracers such as neutral hydrogen (H I) or

## Li et al. (2018) – Where is OH and Does It Trace the Dark Molecular Gas (DMG)?

Hydroxyl (OH) is expected to be abundant in diffuse interstellar molecular gas because it forms along with H2 under similar conditions and forms within a similar extinction range. We have