The Contribution from Circumstellar Dust to the Spectral Energy Distribution of the Large Magellanic Cloud
Date Issued
2013
Date
2013
Author(s)
Lin, Mei-Chun
Abstract
Unresolved distant galaxies can typically only be studied through their spectral energy distributions (SEDs). An SED model of a galaxy usually con- sists of contributions due to starlight (in the UV/optical and near-infrared) and thermal emission of interstellar dust (in the far-infrared).
However, present-day SED models typically do not accounted for dusty envelopes of AGB stars. This might be acceptable for starburst galaxies with a relatively large population of young stars, but it might not accurately repre- sent galaxies with a significant population of dusty Asymptotic Giant Branch (AGB) stars.
In order to estimate the contribution from circumstellar dust, we first gen- erate model stellar SEDs with the population synthesis code Pegase and the star formation history of the LMC from Harris & Zaritsky (2009), which we use to fit the observed SED from previous works at wavelengths less than 1 μm. Then we subtract the best-fit model SED and the interstellar medium (ISM) SED constructed by Bernard et al. (2008) from the observed SED.
We found that there is a significant discrepancy (20 − 40%) between our best-fit SED and the observed SED minus the ISM SED. This result indicates the importance of the contribution from circumstellar dust in the near-infrared SED. Thus, we suggest that an improved stellar spectral library that includes dusty AGB spectra and an improved set of stellar evolutionary tracks that considers dust formalism in stellar winds is needed.
Subjects
光譜能量分佈
大麥哲倫雲
繞恆星塵
恆星演化末期
漸近巨星分支
Type
thesis
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