Herbert Pablo, Université de Montréal
Noel Richardson, Université de Montréal
Anthony Moffat, Université de Montréal
Michael Corcoran, CRESST and X-ray Astrophysics Laboratory
Tomer Shenar, Universität Potsdam
Omar Benvenuto, Universidad Nacional de La Plata
Jim Fuller, University of California - Santa Barbara
Yaël Nazé, Université de Liège
Jennifer Hoffman, University of Denver
Anatoly Miroshnichenko, University of North Carolina at Greensboro
Jesús Apellániz, Centro de Astrobiología (CSIC-INTA)
Nancy Evans, Smithsonian Astrophysical Observatory
Thomas Eversberg, Schnörringen Telescope Science Institute
Ken Gayley, University of Iowa
Ted Gull, NASA Goddard Space Flight Center
Kenji Hamaguchi, CRESST and X-ray Astrophysics Laboratory
Wolf-Rainer Hamann, Universität Potsdam
Huib Henrichs, University of Amsterdam
Tabetha Hole, East Tennessee State University
Richard Ignace, East Tennessee State UniversityFollow
Rosina Iping, Universities Space Research Association
Jennifer Lauer, Smithsonian Astrophysical Observatory
Maurice Leutenegger, University of California - Santa Barbara
Jamie Lomax, University of Oklahoma
Joy Nichols, Smithsonian Astrophysical Observatory
Lida Oskinova, Universität Potsdam
Stan Owocki, University of Delaware
Andy Pollock, European Space Agency
Christopher Russell, NASA Goddard Space Flight Center
Wayne Waldron, Eureka Scientific Inc
Christian Buil, Castanet Tolosan Observatory
Thierry Garrel, Observatoire de Juvignac
Keith Graham, Harvard-Smithsonian Center for Astrophysics
Bernard Heathcote, Barfold Observatory
Thierry Lemoult, Chelles Observatory
Dong Li, Jade Observatory
Benjamin Mauclaire, Observatoire du Val de lArc
Mike Potter
Jose Ribeiro, Observatorio do Instituto Geografico do Exercito
Jaymie Matthews, University of British Columbia
Chris Cameron, Cape Breton University
David Guenther, Institute for Computational Astrophysics
Rainer Kuschnig, University of Vienna
Jason Rowe, NASA Ames Research Center
Slavek Rucinski, University of Toronto
Dimitar Sasselov, Harvard-Smithsonian Center for Astrophysics
Werner Weiss, University of Vienna

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We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system δ Ori A, consisting of a binary O9.5II+early-B(Aa1 and Aa2) with P=5.7 days, and a more distant tertiary(O9 IV P 400 years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV)curve of Aa1. While we are unable to recover RV variations of the secondary star, we are able to constrain several fundamental parameters of this system and determine an approximate mass of the primary using apsidal motion. We also detected second order modulations at 12 separate frequencies with spacings indicative of tidally influenced oscillations. These spacings have never been seen in a massive binary, making this system one of only a handful of such binaries that show evidence for tidally induced pulsations.

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