"Photoionization simulations for the
discriminating astrophysicist since 1978"
What is Cloudy?
Most of the quantitative information we have about the cosmos comes from
spectroscopy. In many cases the light we analyze was produced by atoms in the
first generations of stars and galaxies. Examples include absorption lines
superimposed on distant quasars by intervening galaxies or the intergalactic
medium, emission lines in nebulae, and the emission lines of the quasars
themselves. The spectra are produced by dilute gas where such properties as the gas
kinetic temperature, chemical state, level of ionization, and level populations,
are determined by a host of microphysical processes rather
than by a single temperature. Analytical solutions are seldom possible and
computer solutions are needed to understand
their physical properties.
Numerical simulations make it possible to understand complex physical
environments starting from first principles. Cloudy is designed to do
exactly this. For more information
please see Quantitative spectroscopy of photoionized clouds, in the 2003
Annual Reviews Astronomy & Astrophysics, 41, 517 (available
here), the research monograph Spectroscopic Challenges of
Photoionized Plasmas, ASP Conference Series, vol. 247, edited by Gary
Ferland and Daniel Wolf Savin, or the graduate text Osterbrock & Ferland
Astrophysics of Gaseous Nebulae and Active Galactic Nuclei (the publisher's
web site is here).
Frequently-used links
Instructions for downloading and installing the current stable version are
here
Links to the hotfixes and
known problems web pages.
Just need a copy of Hazy, the documentation? It is on
this ftp site.
The
ViewVC link to the
subversion repository.is
here. Release
versions are under cloudy / tags / release
The
trac project-management and
issue-tracking site is
here.
The revision history is
here.
The Cloudy discussion board is
here.
Frequently asked questions are
here.
The
new on this site page lists changes on this web site.
Other questions? Please post queries on the
discussion
board.
The Cosmic Agitator - Magnetic Fields in the Galaxy
60 years of studies of the interstellar magnetic field
2008 March 26-29 Lexington
http://thunder.pa.uky.edu/magnetic/
The magnetic field of the galaxy was discovered in observations made in
1948. Since
that time, the galactic magnetic field has challenged (and often annoyed)
observers and theorists alike. This meeting will celebrate sixty years of
studies of the interstellar magnetic field.
The meeting will take place in Lexington, Kentucky USA, in the heart of the
beautiful Bluegrass region.
Lexington and its environs are known for picturesque countryside, thoroughbred
race horses, and fine bourbon whiskey asleep many years in the wood.
The main web page is here.
The program is here.
You register for the meeting
here.
The meeting banquet will be held at
Buffalo Trace Distillery, recently named worldwide whiskey distiller of the
year by two leading wine and spirits magazines. Samples of fine Buffalo Trace
spirits at the banquet will, no doubt, lubricate the imaginations of conference
participants as they seek to better envision the complexities of interstellar
magnetism. Banquet attendees may also, if they feel so inclined, raise a glass
to Tom Troland's 60 years
on planet Earth.
Recent
developments on this web site
C07.02.01 is posted (2007 July 7). This is a bug-fix roll
up of C07.02 and is the current stable version. The source, its
documentation Hazy, and the test suite, are all available
here.
This
page summarizes the improvements.
A list of typos in AGN3 is posted
here.
(2007 July 19)
Cloudy now lives in a
subversion repository.
The
ViewVC link is
here. A
trac project-management and
issue-tracking site has been established
here.
Christophe Morisset has
posted a description of his Cloudy 3D tools on
astro-ph. His web
site is here. His tools are
IDL wrappers that drives Cloudy to create 3D nebulae. The following image
is an example and more are in
this paper.:
The effects of a time-variable continuum source
are included, a project done in collaboration
with Will Henney and Robin
Williams and an outgrowth of Henney et al. (2005, ApJ, 621, 328, on the ADS
here). Nick Abel has created a pair of animated gifs showing the time
evolution of an H+ region with PDR after its ionizing star is
turned off and then turned
back on. The first animation shows the
cloud recombining and becoming molecular and the second shows the hydrogen
ionization front moving across the cloud. Time dependent continuum sources will be included in the next
major upgrade, due in early 2007.
Recent
publications
The 2nd edition of
Astrophysics of Gaseous Nebulae by Osterbrock & Ferland is
described
here - they offer a slight
discount off the retail price. A list of typos is
here.
He I iso-electronic sequence Porter & Ferland (2007, ApJ,
664, 586, on astro ph
here)
describe the He-like iso-electronic sequence. Porter et al. (2005,
ApJ, 622, 73L),
describe the treatment of the He0 atom and the He I emission spectrum. Also available on astro-ph
here. Bauman et
al., (2005,
ApJ, 628, 541) give a more complete description of the effects on singlet-triplet mixing,
also available on astro-ph
here. More information and additional tables are available on Ryan Porter's
web site.
He I emission. The physics is described in Porter et al.
(ApJ, 657, 327, ApJ, 622L, 73) and Bauman et al. (ApJ 628, 541).
PDR Physics Abel et al. (ApJS,
161, 65-95) present self-consistent calculations of the spectrum, chemistry, and structure of
an H II region and its associated PDR. It is also on astro-ph
here and a high
resolution version
here.
H2 Physics Shaw et al. (ApJ, 624, 794) describe molecular hydrogen in Cloudy.
It is also available on astro-ph
here or as a high
resolution version
here.
Dynamics Henney et al. (ApJ, 621, 328) describe the treatment of dynamics in the current version of Cloudy.
Also available from astro-ph here.
Grains van Hoof et al (MNRAS 350, 1330) describe the current treatment of grain physics.
Also available from astro-ph here.
Main pages
on this web site
This is a summary of the links that appear at the top of each page.
These pages contain
links to many other pages or resources.
The downloads page has links to the
current and all other versions of
the code.
Hazy, the code's documentation, is here too. The pages also give a list of
problems with the
current version. The
Hot fixes page
gives small changes to the
current version to fix bugs discovered since the last major release. These
will be included in the next release.
Revision history. This page summarizes
improvements to the code.
The new page lists changes on this web site.
The
discussion board page is a place to discuss Cloudy,
quantitative spectroscopy, and the physics of the ISM
The future: The code is still being developed! Its capabilities
have always been limited by processor speed and the atomic/molecular data
base. All of these improve every year. Future plans are discussed here.
Acknowledgements for help with the code.
This includes people who have developed code or discovered bugs, and the funding
agencies that made it possible.
etcetera Miscellaneous information, including
the following: FAQs, acknowledgements, people involved in its development,
the code's history and style convention, computing at Cambridge in the 1970's, what the version numbers mean,
the distinction between notation such as C+2 vs C III, how to call C
from Fortran. Software contributed to drive Cloudy, other spectral
synthesis codes, development software, atomic data, Kentucky, meetings on
spectroscopy, and a collection of cloud images from across the internet.
Site map, search contains an option to
search the site and also a site map.
Last changed
02/04/08.
Return to the Cloudy Home
Page.
Copyright 1978-2006 Gary J. Ferland
