Orion HST

Cloudy workshop

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.

Workshop format

We will cover observation, theory, and apply Cloudy to a wide variety of astronomical environments, including the interstellar medium, AGB stars, Active Galactic Nuclei, Starburst galaxies, and the intergalactic medium. The sessions will consist of a mix of textbook study, using Osterbrock & Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, and application of Cloudy to research problems chosen by participants. No prior experience with Cloudy is assumed.

Participants will break up into small teams and organize research projects of mutual interest. Previous projects are summarized on the participants pages.

How to register

Go to the registration page. There are two steps described there, and you have to do both.


The workshop schedule is on the agenda page. Participants should arrive the evening before the first day, and plan on staying for the full duration of the workshop. The workshop ends with the presentation and discussion of project results late Friday afternoon.

More information

The homework page describes what must be done to prepare for the workshop. The transportation and lodging page gives more information on the workshop location. Updates will be announced on the Yahoo discussion board.

Next workshop

Where:Shangdong University at Weihai, China
When: 2016 June 20-24 Information and registration (now closed)
The next workshop is hosted by Tingui Wang and Lulu Fan and will be held at Shandong University at Weihai, China. Weihai (威海). Weihai is a well-known leisure resort and and is famous for its natural hot springs.

Previous workshops

Where: University of Kentucky, Room B108a of the Young Library of the We are located in Lexington, KY, the heart of the Bluegrass.
When: Tuesday May 29 through the end of Friday June 1.

Where: Queen's University Belfast, Computer Suite (Room F024), Second Floor, Main Physics Building, School of Mathematics and Physics.
When: August 18-22

Where: Leiden University, Observatory computer room, Huygens building
: Oct 10

: Queen's University Belfast, Computer Suite (Room F024), Second Floor, Main Physics Building, School of Mathematics and Physics.
When: January 12-16

Where: Durham University Ogden Center, room OC218.
When: March 26

Where: Nicolaus Copernicus Astronomical Center, Warsaw
When: May 4-8

Where: Inter-University Centre for Astronomy and Astrophysics, Pune, India. The workshop website is here.
When: Sept 21-26