NOAO >   Observing Info >   Approved Programs >   2011A-0151

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Proposal Information for 2011A-0151


PI: Nathan Smith, University of Arizona, nathans@as.arizona.edu
Address: Astronomy Department, 933 N. Cherry, Tucson, AZ 85719, USA

Title: Resolving the Infrared [Fe II] Emission in Circumstellar LBV Shells with NICI

Abstract: This proposal aims to use NICI on Gemini South to spatially resolve the circumstellar shells of luminous blue variables (LBVs) in near-IR adaptive-optics (AO) coronagraphic images in the [Fe II] 1.644 (micron) line. LBVs represent a critical mass-loss phase in the pre-supernova evolution of massive stars, but their fossil shells are currently the only way to constrain the amount of mass lost in an eruptive event. The [Fe II] 1.644 (micron) line is especially bright in LBV circumstellar shells, and coronagraphic AO images will reveal the geometry and spatial extent of the shells; the radius is a critical parameter needed to interpret spectra and model the shells. When combined with near-IR spectroscopy of several other [Fe II] transitions (in a separate proposal), the resolved shell geometry, line ratios, and line kinematics can constrain the ages, densities, compositions, and total gas masses of the nebulae around a number of LBV stars of different initial mass and metallicity. So far this technique has been applied successfully to just the two nearest and brightest examples (Eta Carinae and P Cygni) where the circumstellar gas is easy to resolve, but AO coronagraphic images are essential for fainter targets in the SMC/LMC, and in the Milky Way when the circumstellar gas is close to the extremely bright central stars.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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