Image of Alice in Wonderland at the Mad Hatter's tea party You are cordially invited to afternoon tea and biscuits wine and chocolate

Astronomy Tea Talks at Caltech

Mondays, Hameetman auditorium (Cahill)
Tea:  4.00pm
Talk: 4.15pm

Organized by:

2009 - 2010 season:
21 June 2010 Orly Gnat (Caltech)

"Non-Equilibrium Ionization Processes in Metal-Ion Absorbers"

In this talk I will discuss several processes that give rise to
non-equilibrium ionization in metal-ion absorbers. These include
radiative cooling, fast shock waves, and conductive evaporation of
warm clouds. In each case, I will demonstrate the impact that
departures from equilibrium ionization have on the absorption line
signatures. I will first describe computations of the equilibrium and
non-equilibrium ionization states and cooling efficiencies in
radiatively cooling gas. I will then discuss models of the
non-equilibrium cooling column densities associated with fast
radiative shocks, including the effect of the shock self-radiation on
the "downstream" ionization states. In these models I
self-consistently follow the time-dependent dynamics, ionization,
cooling and radiative transfer equations in one- dimensional stable
shocks. I will describe how the observational signatures depend on the
controlling parameters, including the shock velocity, gas metallicity,
magnetic field, and shock age. Finally, I will present recent
computations of thermally conductive interface layers, that may
surround evaporating clouds embedded in a hot medium. These models
include photoionization by an external radiation field. I will
describe how departures from equilibrium affect the conditions for
which self-consistent evaporating solutions exist, and the metal-ion
columns produced in the evaporating layers.

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Last modified on 20th Jul 2011 by Dominik A. Riechers.  

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