A Coordinated X-ray and Optical Campaign of the Nearest Massive Eclipsing Binary,
$delta$ Orionis Aa: III. Analysis of Optical Photometric MOST and Spectroscopic (Ground Based) Variations


Herbert Pabloaltaffilmark{1},
Noel D. Richardsonaltaffilmark{1},
Anthony F. J. Moffataltaffilmark{1},
Michael Corcoranaltaffilmark{2,3},
Tomer Shenaraltaffilmark{4},
Omar Benvenutoaltaffilmark{5,6},
Jim Fulleraltaffilmark{7,8},
Ya"el Naz'ealtaffilmark{9},
Jennifer L. Hoffmanaltaffilmark{10},
Anatoly Miroshnichenkoaltaffilmark{11},
Jes{'us} Ma'iz Apell'anizaltaffilmark{12},
Nancy Evansaltaffilmark{13},
Thomas Eversbergaltaffilmark{14},
Ken Gayleyaltaffilmark{15},
Ted Gullaltaffilmark{16},
Kenji Hamaguchialtaffilmark{2},
Wolf-Rainer Hamannaltaffilmark{4},
Huib Henrichsaltaffilmark{17},
Tabetha Holealtaffilmark{18},
Richard Ignacealtaffilmark{18},
Rosina Ipingaltaffilmark{3},
Jennifer Laueraltaffilmark{13},
Maurice Leuteneggeraltaffilmark{8},
Jamie Lomaxaltaffilmark{19},
Joy Nicholsaltaffilmark{13},
Lida Oskinovaaltaffilmark{4},
Stan Owockialtaffilmark{20},
Andy Pollockaltaffilmark{21},
Christopher M. P. Russellaltaffilmark{22,23},
Wayne Waldronaltaffilmark{24},
Christian Builaltaffilmark{25},
Thierry Garrelaltaffilmark{26},
Keith Grahamaltaffilmark{27},
Bernard Heathcotealtaffilmark{28},
Thierry Lemoultaltaffilmark{29},
Dong Lialtaffilmark{30},
Benjamin Mauclairealtaffilmark{31},
Mike Potteraltaffilmark{32},
Jose Ribeiroaltaffilmark{33},
Jaymie Matthewsaltaffilmark{34},
Chris Cameronaltaffilmark{35},
David Guentheraltaffilmark{36},
Rainer Kuschnigaltaffilmark{34,37},
Jason Rowealtaffilmark{38},
Slavek Rucinskialtaffilmark{39},
Dimitar Sasselovaltaffilmark{40}, and
Werner Weissaltaffilmark{37}

"1-D'epartement de physique and Centre de Recherche en Astrophysique du Qu'ebec (CRAQ), Universit'e de Montr'eal, C.P. 6128, Succ.~Centre-Ville, Montr'eal, Qu'ebec, H3C 3J7, Canada;
2-CRESST and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771, USA;
3-Universities Space Research Association, 7178 Columbia Gateway Drive, Columbia, MD 21046, USA;
4-Institut f"{u}r Physik und Astronomie, Universit"{a}t Potsdam, Karl-Liebknecht-Str. 24/25, 14476, Potsdam, Germany;
5-Facultad de Ciencias Astron'{o}micas y Geof'{i}sicas, Universidad Nacional de La Plata, 1900 La Plata, Buenos Aires, Argentina;
6-Instituto de Astrofs'{i}ica de La Plata (IALP), CCT-CONICET-UNLP. Paseo del Bosque S/N (B1900FWA), La Plata, Argentina;
7-TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125, USA;
8-Kavli Institute for Theoretical Physics, Kohn Hall, University of California, Santa Barbara, CA 93106, USA;
9-FNRS D'epartement AGO, Universit'e de Li`ege, All'ee du 6 Aout 17, Bat. B5C, 4000, Li`ege, Belgium;
10-Department of Physics & Astronomy, University of Denver, 2112 East Wesley Avenue, Denver, CO 80208, USA;
11-Department of Physics and Astronomy, University of North Carolina at Greensboro, Greensboro, NC 27402-6170, USA;
12-Centro de Astrobiolog{'i}a (CSIC-INTA), ESAC Campus, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain;
13-Smithsonian Astrophysical Observatory, 60 Garden St., Cambridge, MA 02138, USA;
14-Schn"{o}rringen Telescope Science Institute, Waldbr"{o}l, Germany;
15-Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242;
16-Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;

17-Astronomical Institute "Anton Pannekoek", University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands;
18-Department of Physics & Astronomy, East Tennessee State University, Box 70652, Johnson City, TN 37614, USA;
19-HL Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, USA;
20-Bartol Research Institute, University of Delaware, Newark, DE 19716, USA;
21-European Space Agency, Apartado 78, Villanueva de la Canada, E-28691 Madrid, Spain;
22-X-ray Astrophysics Lab, Code 662, NASA Goddard Space Flight Center, Greenbelt, MD
20771 USA;
23-Oak Ridge Associated Universities (ORAU), Oak Ridge, TN 37831 USA;
24-Eureka Scientific Inc., 2452 Dellmer Street, Suite 100, Oakland, CA 94602, USA;
25-Castanet Tolosan Observatory, 6 place Cl'emence Isaure, 31320, Castanet Tolosan, France;
26-Observatoire de Juvignac, 19 avenue du Hameau du Golf, 34990 Juvignac, France;
27-The ConVento Group;
28-Barfold Observatory, Glenhope, Victoria 3444, Australia;
29-Chelles Observatory, 23 avenue H{'e}nin, 77500 Chelles, France;
30-Jade Observatory, Jin Jiang Nan Li, He Bei District, 300251 Tianjin, China;
31-Observatoire du Val de lÕArc, route de Peynier, 13530 Trets, France;
32-3206 Overland Ave, Baltimore, MD 21214 USA;
33-Observatorio do Instituto Geografico do Exercito, Lisboa, Portugal;
34-Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada;
35-Department of Mathematics, Physics & Geology, Cape Breton University, 1250 Grand Lake Road, Sydney, Nova Scotia, Canada, B1P 6L2;
36-Institute for Computational Astrophysics, Dept. of Astronomy and Physics, St Mary's University Halifax, NS B3H 3C3, Canada;
37-University of Vienna, Institute for Astronomy, T"urkenschanzstrasse 17, A-1180 Vienna, Austria;
38-NASA Ames Research Center, Moffett Field, CA 94035, USA;
39-Dept. of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, ON M5S 3H4, Canada;
40-Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;

We report on both high-precision photometry from the textit{MOST} space telescope and ground-based spectroscopy of the triple system $delta$ Ori A consisting of a binary O9.5II+early-B (Aa1 and Aa2) with $P=$ 5.7d, and a more distant tertiary (O9 IV $P >400$ yrs). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for 3 weeks, the textit{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 curve of Aa1. While we are unable to recover radial velocity 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 which show evidence for tidally induced pulsations.

Reference: apj516687
Status: Manuscript has been accepted

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Email: hpablo@astro.umontreal.ca