Dust input from AGB stars in the Large Magellanic Cloud
  The dust-forming population of AGB stars and their input to the interstellar
dust budget of the Large Magellanic Cloud (LMC) are studied with evolutionary
dust models with the main goals (1) to investigate how the amount and
composition of dust from AGB stars vary over galactic history; (2) to
characterise the mass and metallicity distribution of the present population of
AGB stars; (3) to quantify the contribution of AGB stars of different mass and
metallicity to the present stardust population in the interstellar medium
(ISM). We use models of the stardust lifecycle in the ISM developed and tested
for the Solar neighbourhood. The first global spatially resolved reconstruction
of the star formation history of the LMC from the Magellanic Clouds Photometric
Survey is employed to calculate the stellar populations in the LMC. The dust
input from AGB stars is dominated by carbon grains from stars with masses < 4
Msun almost over the entire history of the LMC. The production of silicate,
silicon carbide and iron dust is delayed until the ISM is enriched to about
half the present metallicity in the LMC. For the first time, theoretically
calculated dust production rates of AGB stars are compared to those derived
from IR observations of AGB stars for the entire galaxy. We find good agreement
within scatter of various observational estimates. We show that the majority of
silicate and iron grains in the present stardust population originate from a
small population of intermediate-mass stars consisting of only about 4% of the
total number of stars, whereas in the Solar neighbourhood they originate from
low-mass stars. With models of the lifecycle of stardust grains in the ISM we
confirm a large discrepancy between dust input from stars and the existing
interstellar dust mass in the LMC reported in Matsuura et al. 2009.
