Collaborative Research Using High Mass Binaries to Resolve the Mass Discrepancy: Taking Things to the Extreme

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AST-0506573Douglas GiesGeorgia State UniversityCollaborative Research Using High Mass Binaries to Resolve the MassDiscrepancy: Taking Things to the ExtremeABSTRACTAn observational program will be undertaken to determine the masses of the most massive stars.The work is motivated by significant (factors of two to three) differences in the masses of high massstars derived from evolutionary models compared with those calculated from atmosphericparameters (i.e, surface gravities from Balmer profiles combined with distance, reddening, andbolometric magnitudes). Thus, either problems remain with theories of high mass star evolution(important/unknown physical complications may have not be included), or with the spectroscopicapproach (incorrect surface gravities, luminosities, distances, etc. may be being used). To resolvethe question and ascertain the source of the discrepancy, the masses of binary O stars will bedirectly measured from an analysis of eclipsing double-lined spectroscopic binaries (specialattention will be paid to those with periods 3-5 days which have therefore not interacted). In thefirst year, young associations and clusters in the Milky Way and Magellanic Clouds will bephotometrically surveyed to find eclipsing binaries. Radial velocities for candidates will be obtainedin the second year. The third year will be used to find the orbit solutions, and to calculatespectroscopic and evolutionary masses for comparison with the results.This project includes a significant outreach and undergraduate research component. Thephotometric data (its acquisition for the northern fields and reduction for both northern and southerntargets) will be part of a key project of the National Undergraduate Research Observatory.Undergraduate students in Northern Arizona University Research Experiences for Undergraduatesprogram and MIT field camp will help with the spectroscopic observations and orbit solutions.