@article{PabloRichardsonMoffatetal.2015, author = {Pablo, Herbert and Richardson, Noel D. and Moffat, Anthony F. J. and Corcoran, Michael and Shenar, Tomer and Benvenuto, Omar and Fuller, Jim and Naze, Yael and Hoffman, Jennifer L. and Miroshnichenko, Anatoly and Apellaniz, Jesus Maiz and Evans, Nancy and Eversberg, Thomas and Gayley, Ken and Gull, Ted and Hamaguchi, Kenji and Hamann, Wolf-Rainer and Henrichs, Huib and Hole, Tabetha and Ignace, Richard and Iping, Rosina and Lauer, Jennifer and Leutenegger, Maurice and Lomax, Jamie and Nichols, Joy and Oskinova, Lida and Owocki, Stan and Pollock, Andy and Russell, Christopher M. P. and Waldron, Wayne and Buil, Christian and Garrel, Thierry and Graham, Keith and Heathcote, Bernard and Lemoult, Thierry and Li, Dong and Mauclaire, Benjamin and Potter, Mike and Ribeiro, Jose and Matthews, Jaymie and Cameron, Chris and Guenther, David and Kuschnig, Rainer and Rowe, Jason and Rucinski, Slavek and Sasselov, Dimitar and Weiss, Werner}, title = {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}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, volume = {809}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics}, number = {2}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0004-637X}, doi = {10.1088/0004-637X/809/2/134}, pages = {11}, year = {2015}, abstract = {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 delta 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.}, language = {en} } @article{EvansDeGioiaEastwoodGagneetal.2011, author = {Evans, Nancy Remage and DeGioia-Eastwood, Kathleen and Gagne, Marc and Townsley, Leisa and Broos, Patrick S. and Wolk, Scott J. and Naze, Yael and Corcoran, Michael and Oskinova, Lida and Moffat, Anthony F. J. and Wang, Junfeng and Walborn, Nolan R.}, title = {The search for low-mass companions of b stars in the Carina Nebula cluster trumpler 16}, series = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, volume = {194}, journal = {The astrophysical journal : an international review of spectroscopy and astronomical physics ; Supplement series}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {0067-0049}, doi = {10.1088/0067-0049/194/1/13}, pages = {9}, year = {2011}, abstract = {We have developed lists of likely B3-A0 stars (called "late B" stars) in the young cluster Trumpler 16. The following criteria were used: location within 3' of eta Car, an appropriate V and B - V combination, and proper motion (where available). Color and magnitude cuts have been made assuming an E(B - V) = 0.55 mag +/- 0.1, which is a good approximation close to the center of Trumpler 16. These lists have been cross-correlated with X-ray sources found in the Chandra Carina Complex Project. Previous studies have shown that only very rarely (if at all) do late main-sequence B stars produce X-rays. We present evidence that the X-ray-detected sources are binaries with low-mass companions, since stars less massive than 1.4 M-circle dot are strong X-ray sources at the age of the cluster. Both the median X-ray energies and X-ray luminosities of these sources are in good agreement with values for typical low-mass coronal X-ray sources. We find that 39\% of the late B stars based on a list with proper motions have low-mass companions. Similarly, 32\% of a sample without proper motions have low-mass companions. We discuss the X-ray detection completeness. These results on low-mass companions of intermediate-mass stars are complementary to spectroscopic and interferometric results and probe new parameter space of low-mass companions at all separations. They do not support a steeply rising distribution of mass ratios to low masses for intermediate-mass (5 M-circle dot) primaries, such as would be found by random pairing from the initial mass function.}, language = {en} } @article{RichardsonRussellStJeanetal.2017, author = {Richardson, Noel D. and Russell, Christopher M. P. and St-Jean, Lucas and Moffat, Anthony F. J. and St-Louis, Nicole and Shenar, Tomer and Pablo, Herbert and Hill, Grant M. and Ramiaramanantsoa, Tahina and Corcoran, Michael and Hamuguchi, Kenji and Eversberg, Thomas and Miszalski, Brent and Chene, Andre-Nicolas and Waldron, Wayne and Kotze, Enrico J. and Kotze, Marissa M. and Luckas, Paul and Cacella, Paulo and Heathcote, Bernard and Powles, Jonathan and Bohlsen, Terry and Locke, Malcolm and Handler, Gerald and Kuschnig, Rainer and Pigulski, Andrzej and Popowicz, Adam and Wade, Gregg A. and Weiss, Werner W.}, title = {The variability of the BRITE-est Wolf-Rayet binary, gamma(2) Velorum-I. Photometric and spectroscopic evidence for colliding winds}, series = {Monthly notices of the Royal Astronomical Society}, volume = {471}, journal = {Monthly notices of the Royal Astronomical Society}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0035-8711}, doi = {10.1093/mnras/stx1731}, pages = {2715 -- 2729}, year = {2017}, abstract = {We report on the first multi-colour precision light curve of the bright Wolf-Rayet binary gamma(2) Velorum, obtained over six months with the nanosatellites in the BRITE-Constellation fleet. In parallel, we obtained 488 high-resolution optical spectra of the system. In this first report on the data sets, we revise the spectroscopic orbit and report on the bulk properties of the colliding winds. We find a dependence of both the light curve and excess emission properties that scales with the inverse of the binary separation. When analysing the spectroscopic properties in combination with the photometry, we find that the phase dependence is caused only by excess emission in the lines, and not from a changing continuum. We also detect a narrow, high-velocity absorption component from the He perpendicular to lambda 5876 transition, which appears twice in the orbit. We calculate smoothed-particle hydrodynamical simulations of the colliding winds and can accurately associate the absorption from He perpendicular to to the leading and trailing arms of the wind shock cone passing tangentially through our line of sight. The simulations also explain the general strength and kinematics of the emission excess observed in wind lines such as C III lambda 5696 of the system. These results represent the first in a series of investigations into the winds and properties of gamma(2) Velorum through multi-technique and multi-wavelength observational campaigns.}, language = {en} }