NOAO >   Observing Info >   Approved Programs >   2016A-0417

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Program Information for 2016A-0417


PI: Guy Stringfellow, U. of Colorado, Guy.Stringfellow@colorado.edu
Address: Center for Astrophysics and Space Astronomy, 389 UCB, Boulder, CO 80309-0389 USA

Title: Spectral Confirmation of New Galactic LBV and WN Stars Associated With Mid-IR Nebulae

Abstract: Luminous Blue Variable (LBV) stars represent an extremely rare class and short-lived phase in the lives of very luminous massive stars with high mass loss rates. Extragalactic LBVs are responsible for producing false supernovae (SN), the SN Impostors, and have been directly linked with the progenitors of actual SN, indicating the LBV phase can be a final endpoint for massive star evolution. Yet only a few confirmed LBVs have been identified in the Galaxy. Their stellar evolution is poorly constrained by observations, and the physical reason for their unstable nature, both in terms of moderate spectral and photometric variability of a few magnitudes and the giant eruptions {it a la} $eta$ Car that rival SN explosions, remains a mystery. Newly discovered mid-IR shells act as signposts, pointing to the central massive stars (LBV and Wolf-Rayet [WR] stars) that produced them. We have undertaken a spectroscopic survey of possible progenitor stars within these shells and are discovering that many are LBVs and WN-type WR transitional stars. This proposal will complete the southern IR spectral survey searching for the progenitor stars that produce mid-IR shells. Upon completion the survey will have resulted in a substantial increase of new WRs and candidate LBVs for continued future study. Spectral analysis provides insight into the winds and physical properties of these rare and important objects, and will lead to a better understanding of the physics driving giant eruptions and LBV variability.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016A):  SOAR/OSIRIS -- 3n on Feb 29 - Mar 05 2016
Run 2 (2016A):  CT-1.3m/ANDI -- 16hrs


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