The 2017 release of Cloudy

G. J. Ferland, M. Chatzikos, F. Guzmán, M. L. Lykins, P. A.M. Van Hoof, R. J.R. Williams, N. P. Abel, N. R. Badnell, F. P. Keenan, R. L. Porter, P. C. Stancil

Research output: Contribution to journalReview articlepeer-review

916 Scopus citations


We describe the 2017 release of the spectral synthesis code Cloudy, summarizing the many improvements to the scope and accuracy of the physics which have been made since the previous release. Exporting the atomic data into external data files has enabled many new large datasets to be incorporated into the code. The use of the complete datasets is not realistic for most calculations, so we describe the limited subset of data used by default, which predicts significantly more lines than the previous release of Cloudy. This version is nevertheless faster than the previous release, as a result of code optimizations. We give examples of the accuracy limits using small models, and the performance requirements of large complete models. We summarize several advances in the H-and He-like iso-electronic sequences and use our complete collisional-radiative models to establish the densities where the coronal and local thermodynamic equilibrium approximations work.

Original languageEnglish
Pages (from-to)385-438
Number of pages54
JournalRevista Mexicana de Astronomia y Astrofisica
Issue number2
StatePublished - Oct 2017

Bibliographical note

Funding Information:
GJF acknowledges support by NSF (1108928; and 1109061), NASA (10-ATP10-0053, 10-ADAP10-0073, and NNX12AH73G), and STScI (HST-AR-12125.01, GO-12560, and HST-GO-12309). MC acknowledges support by NASA (HST-AR-14286.001-A). FG acknowledges support by NSF grant 1412155. PvH was funded by the Belgian Science Policy Office through the ESA Prodex program and contract no. BR/154/PI/MOLPLAN. FPK acknowledges support from the UK Science and Technology Facilities Council.


  • Atomic processes
  • Galaxies: active
  • Methods: numerical
  • Molecular processes
  • Radiation mechanisms: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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