The Chandra Delta Ori Large Project: Occultation Measurements of the Shocked Gas in the Nearest Eclipsing O-Star Binary

Corcoran, Michael; Nichols, Joy; Leutenegger, Maurice; Hole, Tabetha; Gayley, Ken; Russell, Chris; Hoffman, Jennifer; Lomax, Jamie; Richardson, Noel; Waldron, Wayne; Owocki, Stan; Maíz Apellániz, Jesús; Hamann, W. R.; Gull, Ted; Ignace, Richard; Iping, Rosina; Rauw, Gregor; Walborn, Nolan; Naze, Yael; Pollock, Andy; Evans, Nancy; Moffat, Anthony; Hamaguchi, Kenji; Oskinova, Lida
Massive Stars: From α to Ω, held 10-14 June 2013 in Rhodes, Greece; Online at, id.60 (2013).


Delta Ori is the nearest massive, single-lined eclipsing binary (O9.5 II+OB, P=5^{d}.7324). High resolution X-ray spectrometry offers a unique opportunity to geometrically measure the dynamics of the shocked gas around the primary star. We summarize our recent campaign of phase-constrained high-resolution X-ray spectra obtained with the CHANDRA/HETGS plus high-precision photometry with MOST. These observations provide local measurement of the distribution of the embedded, X-ray emitting shocks in the wind of an O star via radial velocity variations and occultation effects, along with standard f/i ratio diagnostics, and enable us to look for correlations with the broad-band photometric variability. We discuss how these observations can help determine the primary star's clumping-corrected mass loss rate, and resolve critical uncertainties in our understanding of the connection between stellar and mass loss parameters.