CLOUDY 90: Numerical Simulation of Plasmas and Their Spectra

TLDR

CLOUDY is a large‑scale spectral synthesis code that simulates physical conditions in astronomical plasmas to predict their emitted spectra. The paper presents CLOUDY version 90, highlighting updates to its atomic database and numerical methods relative to the previous version C84. CLOUDY v90 employs updated computational methods and an expanded atomic database, discusses uncertainties and future development, and offers web access to its Fortran source, documentation, and database. CLOUDY is freely available and widely used for analyzing and interpreting emission‑line spectra.

Abstract

ABSTRACT CLOUDY is a large‐scale spectral synthesis code designed to simulate fully physical conditions within an astronomical plasma and then predict the emitted spectrum. Here we describe version 90 (C90) of the code, paying particular attention to changes in the atomic database and numerical methods that have affected predictions since the last publicly available version, C84. The computational methods and uncertainties are outlined together with the direction future development will take. The code is freely available and is widely used in the analysis and interpretation of emission‐line spectra. Web access to the Fortran source for CLOUDY, its documentation Hazy, and an independent electronic form of the atomic database is also described.