SEARCHING FOR COOL DUST IN THE MID-TO-FAR INFRARED: THE MASS-LOSS HISTORIES OF THE HYPERGIANTS μ Cep, VY CMa, IRC+10420, AND ρ Cas

Journal Article · Tue Mar 15 04:00:00 EDT 2016 · Astronomical Journal (Online)

DOI:https://doi.org/10.3847/0004-6256/151/3/51· OSTI ID:22520008

Shenoy, Dinesh; Humphreys, Roberta M.; Jones, Terry J.; Gehrz, Robert D. ^[1]; Marengo, Massimo ^[2]; Helton, L. Andrew ^[3]; Hoffmann, William F.; Skemer, Andrew J.

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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. Department of Physics, Iowa State University, Ames, IA 50011 (United States)
3. USRA-SOFIA Science Center, NASA Ames Research Center, Moffett Field, CA 94035 (United States)

We present mid- and far-IR imaging of four famous hypergiant stars: the red supergiants μ Cep and VY CMa, and the warm hypergiants IRC +10420 and ρ Cas. Our 11–37 μm SOFIA/FORCAST imaging probes cool dust not detected in visual and near-IR imaging studies. Adaptive optics 8–12 μm imaging of μ Cep and IRC +10420 with MMT/MIRAC reveals extended envelopes that are the likely sources of these stars’ strong silicate emission features. We find μ Cep’s mass-loss rate to have declined by about a factor of five over a 13,000 year history, ranging from 5 × 10{sup −6} down to ∼1× 10{sup −6} M{sub ⊙} yr{sup −1}. The morphology of VY CMa indicates a cooler dust component coincident with the highly asymmetric reflection nebulae seen in the visual and near-IR. The lack of cold dust at greater distances around VY CMa indicates that its mass-loss history is limited to the last ∼1200 years, with an average rate of 6 × 10{sup −4} M{sub ⊙} yr{sup −1}. We find two distinct periods in the mass-loss history of IRC +10420 with a high rate of 2 × 10{sup −3} M{sub ⊙} yr{sup −1} until approximately 2000 years ago, followed by an order of magnitude decrease in the recent past. We interpret this change as evidence of its evolution beyond the RSG stage. Our new infrared photometry of ρ Cas is consistent with emission from the expanding dust shell ejected in its 1946 eruption, with no evidence of newer dust formation from its more recent events.

• OSTI ID: 22520008
• Journal Information: Astronomical Journal (Online), Journal Name: Astronomical Journal (Online) Journal Issue: 3 Vol. 151; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COSMIC DUST
FAR INFRARED RADIATION
GIANT STARS
INFRARED SPECTRA
INTERMEDIATE INFRARED RADIATION
MASS TRANSFER
MORPHOLOGY
NEBULAE
PHOTOMETRY
REFLECTION
SILICATES
STELLAR WINDS