\documentstyle{preprint}
\begin{document}
\title{DUST AND IONIZED GAS IN ELLIPTICAL GALAXIES}
\author{Paul Goudfrooij\/\thanks{Affiliated to the Astrophysics Division,
European Space Agency}\\
\\
Space Telescope Science Institute\\
\\
3700 San Martin Drive\\
\\
Baltimore, MD 21218\\
\\
and\\
\\
European Southern Observatory\\
\\
Karl-Schwarzschild-Strasse 2\\
\\
D-85748 Garching, Germany}

\pub{{\em the Astronomical Society of the Pacific's Conference Series},\\
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{\em this invited review was given at the Second Stromlo Symposium,}\\
~\\
The Nature of Elliptical Galaxies,\\
~\\
{\em held 24--29 August 1996 in Canberra, Australia.}\\
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{\em The Proceedings will be edited by M.~Arnaboldi, G.~S.\ da Costa \& P.~Saha}}

\maketitle

\begin{abstract}
Results from {\it IRAS\/} and recent X-ray and optical surveys are reviewed 
to discuss the properties and nature of the interstellar medium in
elliptical galaxies.

As to the dust component, there is a strong contrast with the situation
among spiral galaxies in that masses of dust in ellipticals as derived
from optical extinction are an order of magnitude {\it lower\/} than
those derived from {\it IRAS\/} data.  I argue that this dilemma can be
resolved by assuming an extra, extended, {\it diffusely distributed
component\/} of dust which is not detectable in optical data.

Bona-fide global correlations among ISM components---and between ionized
gas, dust, and global (stellar) properties of ellipticals---are hard to
find, which most probably reflects an external origin of dust and
ionized gas in ellipticals.

A strong correlation is found, however, between the
H$\alpha$+\mbox{[N~{\sc II}]} luminosity and the optical luminosity within
the region occupied by the ionized gas, which suggest hot (post-AGB
and/or blue HB) stars within the old stellar population being a dominant
source of ionization of the gas.

\end{abstract}
\end{document}