The global gas and dust budget of the Large Magellanic Cloud: AGB stars
  and supernovae, and the impact on the ISM evolution
  We report on an analysis of the gas and dust budget in the the interstellar
medium (ISM) of the Large Magellanic Cloud (LMC). Recent observations from the
Spitzer Space Telescope enable us to study the mid-infrared dust excess of
asymptotic giant branch (AGB) stars in the LMC. This is the first time we can
quantitatively assess the gas and dust input from AGB stars over a complete
galaxy, fully based on observations. The integrated mass-loss rate over all
intermediate and high mass-loss rate carbon-rich AGB candidates in the LMC is
8.5x10^-3 solar mass per year, up to 2.1x10^-2 solar mass per year. This number
could be increased up to 2.7x10^-2 solar mass per year, if oxygen-rich stars
are included. This is overall consistent with theoretical expectations,
considering the star formation rate when these low- and intermediate-mass stars
where formed, and the initial mass functions. AGB stars are one of the most
important gas sources in the LMC, with supernovae (SNe), which produces about
2-4x10^-2 solar mass per year. At the moment, the star formation rate exceeds
the gas feedback from AGB stars and SNe in the LMC, and the current star
formation depends on gas already present in the ISM. This suggests that as the
gas in the ISM is exhausted, the star formation rate will eventually decline in
the LMC, unless gas is supplied externally. Our estimates suggest `a missing
dust-mass problem' in the LMC, which is similarly found in high-z galaxies: the
accumulated dust mass from AGB stars and possibly SNe over the dust life time
(400--800 Myrs) is significant less than the dust mass in the ISM. Another dust
source is required, possibly related to star-forming regions.
