Computation of Dielectronic Recombination Data
for Spectral Simulations of Astrophysical Plasmas
(Above) The expanding "death shroud" of a dead star. The central
star in the above image (the circular white dot at the center of the spherical
shell) is a hot (Tstar = 130,000 K) white dwarf, the collapsed
carbon/oxygen core of this formerly sun-like star. Its envelope enshrouds
the dead star in a spherical shell expanding outward at about 35 km/s.
The light emitted by the shell in the above image has its origin
in an electron in an energetically excited state of the O++
atomic ion making a downward transition to a less energetic one (a transition
within the 2p2 ground state of doubly-ionized oxygen: 1D2
- 3P2, for the experts out there). Energetic ultraviolet
photons emitted by the dead star are responsible for producing this ion
of oxygen as well as heating the gas to sufficiently high temperatures
(Tgas= 15,000 K) to cause this outermost electron to become
excited. Courtesy of George Jacoby (NOAO).
The team, based at the Department
of Physics of Western Michigan University
Dr. Thomas
W. Gorczyca
Dr. Oleg Zatsarinny
Dr. Kirk
T. Korista
Our Collaborators:
Dr. Nigel
R. Badnell
Dr. Igor Bray
Dr. Gary
Ferland
Dr. Brendan McLaughlin
Dr. Daniel Wolf Savin
(At right:) A cartoon of the process known as Dielectronic
Recombination (DR), whereupon an unbound electron finds itself bound to
an atomic ion (an atom missing 1 or more of its electrons), with the
"help" of one of the already bound electrons. This process is very important
in dertermining the elemental abundances of cosmic gas clouds that are
"photo"-ionized by energetic ultraviolet light. Only recently have
accurate DR rates from theory and laboratory experiment become available.
Links to ASCII (text) files containing fitting parameters
to rate coefficients, and other results
Thomas W. Gorczyca & Kirk T. Korista
Department of Physics
Western Michigan University
Kalamazoo, MI 49008-5252
email: thomas.gorczyca@wmich.edu
kirk.korista@wmich.edu
last edited: 7 July 2005