• Theoretical Astrophysics
• Atomic & molecular physics
• Quantitative spectroscopy, quasars, emission lines.
• Numerical simulations of non-equilibrium plasmas
• Origin of the chemical elements

• B.S. (Physics) University of Texas (1973)
• Ph.D., University of Texas (1978), (Ph.D. Genealogy at the American Astronomical Society)
• Research Associate, Cambridge University (1978 - 1980)
• Assistant, Associate Professor, University of Kentucky (1980 - 1985)
• Associate, Full Professor, Ohio State (1985-1992)
• Professor, University of Kentucky, (1992 - present)

• 2023 Nature Astronomy named Cloudy the first Code of Honor in its  Access Code series. Ferland's interview. 
• 2022 Elected Fellow of the Americal Association for the Advancement of Science
• 2022 Senior Visiting Fellow, Institue of Astronomy, Cambridge University
• 2021 Elected Fellow of the American Astronomical Society
• 2019 Kavli Visiting Fellowship, DAMPT (Applied Maths and Theoretical Physics), Cambridge University
• 2017-2018, Visiting Research Professor, School of Mathematics and Physics, Queen’s University Belfast, Northern Ireland
• 2016-2017 Catedratico de Excelencia Guillermo Haro,  INAOE, Tonantzintla, Puebla, Mexico
• 2016 Festschrift UNAM Mexico City
• 2016 Kirwan Memorial Prize, University of Kentucky
• 2015 Visiting Astronomer, Nicolaus Copernicus Astronomical Center CAMK, Warsaw, Poland
• 2015 Visitor, Durham University, England
• 2014-2015 Leverhulme Visiting Professor, Queen’s University Belfast, Northern Ireland
• 2014 Netherlands Nova Lecturer
• 2009-2012 Publications Board, American Astronomical Society (AAS)
• 2007-2008 Senior Visiting Fellow, Cambridge University
• 2006-2012, Organizing Committee Commission 34, Interstellar Matter, International Astronomical Union
• 2007-2008, Visiting Associate, Darwin College, Cambridge University
• 2007-2008, Council, American Astronomical Society (AAS)
• 2007 Sackler Visiting Fellow, Cambridge University
• 2003-2009, Organizing Committee Division VI Interstellar Matter, International Astronomical Union
• 2002-2005, Distinguished Visiting Fellowship, Centre for Experimental Physics, Queen’s University Belfast, Northern Ireland
• 2002-2003, University Research Professor, University of Kentucky
• 1998-1999, Visiting Professor, Canadian Institute for Theoretical Astrophysics, University of Toronto, Canada
• 1992-1993, Visiting Astronomer, Cerro Tololo Interamerican Observatory, La Serena, Chile
• 1992 Senior Visiting Fellow, Cambridge University
• 1991 NRC Astronomy and Astrophysics Decadal Survey, member, Theoretical and Laboratory Astrophysics
• 1990 Visiting Fellow, Joint Institute for Laboratory Astrophysics, University of Colorado, Boulder
• 1987 Senior Visiting Fellow, Cambridge University
• 1979 Elected Fellow of the Royal Astronomical Society

Fellow of the American Association for the Advancement of Science
Fellow of the American Astronomical Society
Fellow of the Royal Astronomical Society

A list of the Ph.D.'s awarded under my supervision is on the American Astronomical (AAS) Ph.D. genealogy page,

Graduate students – I love working with students, but I cannot accept any new ones. I would love to work with you as a co-advisor with other faculty serving as your primary.

The hydrogen atoms in the water we drink and the helium in a party balloon were produced in the creation of the universe nearly 14 billion years ago.  The oxygen we breath was produced in massive stars that exploded five to ten billion years ago.  Dying stars very similar to our sun produced the nitrogen that makes up most of our air.  Elements like gold and platinum were produced during the coalescence of pairs of neutron stars.  The atoms in our body were in two or three stars before our solar system was formed.  How do we know these things?  

Nearly all of the quantitative information we have about the cosmos is the result of spectroscopy, the science of using spectra to make physical measurements. We can directly measure the temperature, density, pressure, or composition of a cloud of gas or a star, using a telescope and a spectrometer.  The spectrum forms in highly non-equilibrium gas and dust. Analytical theory cannot be used to understand the conditions, so numerical simulations are required. The computer program Cloudy does this - it calculates the ionization, chemistry, radiation transport, and dynamics simultaneously and self consistently, building from a foundation of atomic and molecular processes.

Some time ago I wrote a non-technical article on quantitative spectroscopy, Cloudy, and my research into the evolution of the universe.  Although the article is getting old, the introduction in it is still good. 

More recently, UK PR did an article and video on the Cloudy project.  They have also done stories about Cloudy and JWST, and Maryam Dehghanian and Priyanka Chakraborty, two UK students who did Cloudy-related research.

I began developing Cloudy at the Institute of Astronomy, Cambridge, in August 1978.  It is named after the famed East Anglian weather.  Some links:

• Information about Cloudy
• nublado.org, the project website, where you can download the source, data, and documentation
• Cloudy Workshops, where participants can learn about spectroscopy and Cloudy.  The workshop began a world tour in Lexington in 2012, visited Belfast (NI), Durham (UK), Leiden (Netherlands), Warsaw (Poland), Pune (India), Shangdong (China), and ended in July of 2017 in Tonantzintla (Mexico).  A world tour map is here.  Later workshops have been held in Belfast (NI), Chiang Mai (Thailand), Lexington, and Cambridge. 
• An article UK PR did on the Cloudy project in late 2018
• The NASA ADS list of the major review articles on Cloudy.

Cloudy: simulations of astronomical clouds and their spectra

What it does

Nearly all of the quantitative information we have about the cosmos is the result of spectroscopy, the science of using spectra to make physical measurements. We can directly measure the temperature, density, pressure, or composition of a cloud of gas or a star, using a telescope and a spectrometer.

The spectrum forms in highly non-equilibrium gas and dust. Analytical theory cannot be used to understand the conditions so numerical simulations are required. Cloudy is a code that does this - it calculates the ionization, chemistry, radiation transport, and dynamics simultaneously and self consistently, building from a foundation of atomic and molecular processes. The result is a prediction of the conditions in the material and its observed spectrum. These predictions depend on detailed atomic and molecular processes, a complication, but is also why the spectrum reveals so much about its source.

Some time ago I wrote a non-technical article on quantitative spectroscopy, Cloudy, and my research into the evolution of the universe.  Although the article is getting old, the introduction in it is still good.  More recently, UK PR did an article and video on the Cloudy project.

The development of Cloudy is described in a series of review papers.  A NASA ADS library listing these papers is here.

The code and its atomic database

The main Cloudy website is here. It has instructions for how to download the code and its data, and how to build a working executable. 

Cloudy has been open source since 1982.  It is provided for general use under an open source license.  The code lives in a GitLab source code control system repository kindly hosted by our College of Arts & Sciences.  You can view the entire Cloudy svn repository, including our development versions, here.

We use the doxygen markup to document the source code's structure.  The doxygen view of the current release is here. 

Community use of Cloudy

The Cloudy user group website is here.  Here you can ask questions and receive news about updates.

Cloudy is one of the more highly cited codes in astrophysics. I ask that users cite Cloudy's documentation when the code is used in a publication. Today more than 300 papers cite Cloudy each year. These ADS citations are one way to measure the code's use. There have been several main references over the years.

Originally, I asked that users cite Hazy, the documentation included in the code's download. This link gives links to the roughly 1100 papers that cited Hazy.

Later, I asked that users cite Ferland et al. (1998), a review article published in PASP. This link produces a rank-ordered list of the most highly cited ADS astronomy research papers published in 1998. In early 2018 it had roughly 1800 citations and was the 7th most cited paper. (The following Astronomy research journals are included in this ranking: ApJ, ApJL, ApJS, A&A, AJ, MNRAS, PASP, Rev Mex.)

The 2013 release, called C13, is described by Ferland et al. (2013). This link produces a rank-ordered list of the most highly cited ADS papers published in 2013. In early 2018 this paper had roughly 460 citations and was the 10th most cited paper.

The 2017 release, called C17, is described by Ferland et al. (2017).

Cloudy workshops

These are schools where participants can learn about spectroscopy and Cloudy.  Its website is here.  The workshop began a world tour in Lexington in 2012, visited Belfast (NI), Durham (UK), Leiden (Netherlands), Warsaw )Poland), Pune (India), Shangdong (China), and ended in July of 2017 in Tonantzintla (Mexico).  A world tour map is here.

The next workshop is in Chiang Mai Thailand in May 2018.  The local website is here.

Astrophysical applications of Cloudy

Osterbrock & Ferland 2006, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, 2nd edition (Don always called this "AGN3"). This is a graduate text that covers much of the physics in Cloudy, emission lines in nebulae, and Active Nuclei.

Ferland 2003, ARA&A, 41, 517, Quantitative Spectroscopy of Photoionized Clouds A review of the status of the field and the outstanding research problems.

Hamann & Ferland, ARA&A, 37, 487, Elemental Abundances in Quasistellar Objects: Star Formation and Galactic Nuclear Evolution at High Redshifts. This applies Cloudy to measure abundances from the strong lines seen in Active Nuclei and finds a luminosity - metallicity correlation.

Ferland 2001, PASP, 113, 41, Physical Conditions in the Orion H II Region A review of the current status and problems for the Orion Nebula, the brightest and nearest H II region.

This is a link to a page on the impact craters of Kentucky. 

The Cloudy Project

I began developing Cloudy at the Institute of Astronomy, Cambridge, in August 1978.  It is named after the famed East Anglian weather.  Some links:

• Information about Cloudy
• nublado.org, the project website, where you can download the source, data, and documentation
• Cloudy Workshops, where participants can learn about spectroscopy and Cloudy.  The workshop began a world tour in Lexington in 2012, visited Belfast (NI), Durham (UK), Leiden (Netherlands), Warsaw (Poland), Pune (India), Shangdong (China), and ended in July of 2017 in Tonantzintla (Mexico).  A world tour map is here.  Later workshops have been held in Belfast (NI), Chiang Mai (Thailand), Lexington, and Cambridge. 
• An article UK PR did on the Cloudy project in late 2018
• The NASA ADS list of the major review articles on Cloudy.

Textbooks and reviews

• Astrophysics of Gaseous Nebulae, Osterbrock & Ferland, AGN3, 
•  

The Level5 project at Carengie has a list of older papers on basic astrophysics

How to write a paper

Writing effectively is the most important skill a scientist can have.  Here is a nice summary of how to write a scientific paper.

My summary of the most important steps in writing a paper are:

Start with a good outline.  It is easier to get an outline organized than a pile of words.  The outline will show the sections, the paragraphs, and the contents of each paragraph.

The paragraph is the basic building block of a paper.  It starts with a topic sentence that explains the mission of the paragraph.  There are several sentences that carry out this misssion.  Then there is a concluding sentence that reaches the concluding of the paragraph.

Scientic writing is ver terse.  Avoid extra words or bridge passages.  Fewer words are better.  Remember that  your audience ran out of time last week.