TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 65 (No. 10), pp. 1127-1132, 2013

Modeling the infrared extinction toward the galactic center

Jian Gao1, Aigen Li2, and B. W. Jiang1

1Department of Astronomy, Beijing Normal University, Beijing 100875, China
2Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA

(Received December 26, 2012; Revised May 24, 2013; Accepted May 29, 2013; Online published October 24, 2013)

Abstract: We model the ∼1-19μm infrared (IR) extinction curve toward the Galactic Center (GC) in terms of the standard silicate-graphite interstellar dust model. The grains are taken to have a power law size distribution with an exponential decay above some size. The best-fit model for the GC IR extinction constrains the visual extinction to be AV ∼ 38-42 mag. The limitation of the model, i.e., its difficulty in simultaneously reproducing both the steep ∼1-3 μm near-IR extinction and the flat ∼3-8 μm mid-IR extinction is discussed. We argue that this difficulty could be alleviated by attributing the extinction toward the GC to a combination of dust in different environments: dust in diffuse regions (characterized by small RV and steep near-IR extinction), and dust in dense regions (characterized by large RV and flat UV extinction).
Key words: ISM: dust, extinction - infrared: ISM - Galaxy: center.

Corresponding author E-mail: jiangao@bnu.edu.cn

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