NOAO >   Observing Info >   Approved Programs >   2014B-0131

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Proposal Information for 2014B-0131


PI: Chip Kobulnicky, University of Wyoming, chipk@uwyo.edu
Address: Physics Department, 1000 E. University, Laramie, WY 82071

CoI: Raman Prinja, University College London
CoI: Ronny Blomme, Royal Observatory of Belgium
CoI: Danielle Fenech, University College, London
CoI: Jack Morford, University College, London

Title: The Discordant Mass-Loss Rates of Massive Stars: New Solutions from an Halpha and Radio Survey of Cyg OB2

Abstract: the mass loss rates for massive stars determine the final stellar mass, and thereby, the type of compact stellar remnant for all stars more massive than about 8 M_\odot. The amount of mass shed during main- and post-main-sequence evolution determines whether a star becomes a black hole or a neutron star and specifies the type of supernova or gamma-ray burst that it may produce. Knowledge of stellar mass loss remains the most uncertain parameter in massive star evolution because of the unknown amount of clumping in the stellar winds, with discrepancies exceeding an order of magnitude between various observational results and theoretical expectations! We propose WIYN Hydra echelle H(alpha) spectroscopy of ~70 O supergiants and dwarfs and B supergiant stars in Cygnus OB2 where mass loss rates will also be measured using the CygOB2 Radio Survey (COBRaS; an e-Merlin Legacy Survey). The H(alpha) spectra will enable an independent, contemporaneous measurement of wind-driven mass loss in a large sample of early type stars. Consistent analysis of the H(alpha) and radio diagnostics will provide new perspectives on the radial stratification of wind clumping and will constrain physical differences in clumping properties of weaker versus stronger winds as a function of spectral type/temperature/evolutionary stage.


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