PI: Nathan Smith, University of Arizona, firstname.lastname@example.org
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.
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