文章基本信息

标题：Thermal Emission in the Southwest Clump of VY CMa
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作者：Michael S. Gordon ; Terry J. Jones ; Roberta M. Humphreys 等
期刊名称：The Astronomical journal
印刷版ISSN：0004-6256
电子版ISSN：1538-3881
出版年度：2019
卷号：157
期号：2
页码：1-7
DOI：10.3847/1538-3881/aaf5cb
语种：English
出版社：American Institute of Physics
摘要：We present high spatial resolution LBTI/NOMIC 9–12 μm images of VYCMa and its massive outflow feature, the Southwest (SW) Clump. Combined with high-resolution imaging from the Hubble Space Telescope (0.4–1μm) and LBT/LMIRCam (1–5μm), we isolate the spectral energy distribution (SED) of the clump from the star itself. Using radiative-transfer code DUSTY, we model both the scattered light from VYCMa and the thermal emission from the dust in the clump to estimate the optical depth, mass, and temperature of the SWClump. The SWClump is optically thick at 8.9 μm with a brightness temperature of ∼200 K. With a dust chemistry of equal parts silicates and metallic iron, as well as assumptions on grain size distribution, we estimate a dust mass of 5.4×10 −5 M e . For a gas-to-dust ratio of 100, this implies a total mass of 5.4×10 −3 M e . Compared to the typical mass-loss rate of VYCMa, the SWClump represents an extreme, localized mass-loss event from 300 yr ago.
关键词：stars: individual (VY CMa);stars: mass-loss;stars: winds, outflows;supergiants