NOAO >   Observing Info >   Approved Programs >   2001A-0064

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Proposal Information for 2001A-0064


PI: Douglas Gies, Georgia State University, gies@chara.gsu.edu
Address: University Plaza, Atlanta, GA 30303, U.S.A.

CoI: Peter S. Conti, University of Colorado
CoI: Philip Massey, Lowell Observatory
CoI: Laura Penny, College of Charleston
CoI: Wenjin Huang, Georgia State University
CoI: Debra Wallace, Georgia State University

Title: Binary frequency and rotational velocities of very young OB stars in M17

Abstract: Fifteen very young OB stars have recently been discovered in the Galactic HII region M17. This cluster represents the excitation source in the nearest giant HII region in our Galaxy. Six of the stars show evidence for stellar discs, but the others appear to have cleared away their birth material. Could the latent presence of discs be coupled to either stellar companions or the angular momentum of the stars? This study will provide clues to the connections among these quantities through an investigation of the binary frequency and rotational velocities of the sample using spectra from the red region. The spectroscopic binary fraction for cluster OB stars is ~ 61% and the V \sin i distribution is also well known. These parameters have not yet been studied in a newly born OB cluster. The investigation will show if massive stars are born as rapid rotators, and will help us understand the role of binaries in the formation of massive stars and the dynamics of young clusters. As a bonus, the multiple spectra to be acquired can be co-added to give high S/N spectra for each star which can then be analyzed using modern stellar wind/atmosphere models to determine the luminosity and effective temperature. The precise spectral characteristics and classifications can be used to obtain a more certain distance to M17 using spectroscopic parallax.


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