Thermal Emission in the Southwest Clump of VY CMa

Journal Article · Fri Feb 01 04:00:00 EST 2019 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AAF5CB· OSTI ID:22897277

Gordon, Michael S.; Jones, Terry J.; Humphreys, Roberta M. ^[1]; Ertel, Steve; Hinz, Philip M.; Hoffmann, William F.; Stone, Jordan; Spalding, Eckhart; Vaz, Amali ^[2]

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1. Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States)
2. Steward Observatory, Department of Astronomy, University of Arizona, 993 N. Cherry Avenue, Tucson, AZ 85721 (United States)

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 (0.4–1 μm) 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{sup −5} M{sub ⊙}. For a gas-to-dust ratio of 100, this implies a total mass of 5.4 × 10{sup −3} M{sub ⊙}. Compared to the typical mass-loss rate of VY CMa, the SW Clump represents an extreme, localized mass-loss event from ≲300 yr ago.

• OSTI ID: 22897277
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 2 Vol. 157; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BRIGHTNESS
COMPARATIVE EVALUATIONS
COSMIC DUST
DISTRIBUTION
EMISSION
ENERGY SPECTRA
GRAIN SIZE
IRON
MASS TRANSFER
RADIANT HEAT TRANSFER
SILICATES
SPACE
SPATIAL RESOLUTION
STARS
STELLAR WINDS
TELESCOPES