A new dust budget in the large magellanic cloud

Abstract

The origin of dust in a galaxy is poorly understood. Recently, surveys of the LargeMagellanic Cloud (LMC) have provided astrophysical laboratories for dust studies. Using a method of population synthesis, we investigate the contributions of dust produced by asymptotic giant branch (AGB) stars, common envelope (CE) ejecta and Type II supernovae (SNe II) to the total dust budget in the LMC. Based on our models, the dust production rates (DPRs) of AGB stars in the LMC are between about 2.5 × 10-5 and 4.0 × 10-6M⊙ yr-1. The uncertainty mainly results from different models for the dust yields of AGB stars. The DPRs of CE ejecta are about 6.3 × 10-6 (the initial binary fraction is 50 per cent). These results are within the large scatter of several observational estimates. AGB stars mainly produce carbon grains, which is consistent with observations. Most of the dust grains manufactured by CE ejecta are silicate and iron grains. The contributions of SNe II are very uncertain. Compared with SNe II without reverse shock, the DPRs of AGB stars and CE ejecta are negligible. However, if only 2 per cent of dust grains produced by SNe II can survive after reverse shock, the contributions of SNe II are very small. The total dust masses produced by AGB stars in the LMC are between 2.8 × 104 and 3.2 × 105M⊙, and those produced by CE ejecta are about 6.3 × 104. They are much lower than the values estimated by observations. Therefore, there should be other dust sources in the LMC.