V444 Cyg

V444 Cyg is a short period, colliding wind binary system that consists of a main-sequence O star and nitrogen-rich Wolf-Rayet star. Because the winds from both stars are strong, a shock forms between them. It is the canonical system for both radiative braking (Owocki & Gayley 1995) and radiative inhibition (Stevens & Pollock 1994), and without these processes the WN wind would slam into the surface of the O star. My collaborators and I recently used optical polarimetric and X-ray data to detect the effects of these processes in the system for the first time (Lomax et al. 2015). In addition, we found that the quick period of the system causes the Coriolis force to distort the wind collision region so that it is not symmetric about the lines of centers connecting the two stars. Currently, we are actively pursuing follow up observations to better determine the polarization behavior of V444 Cyg's emission lines.

beta Lyrae

Beta Lyrae is a massive binary system currently undergoing mass transfer via Roche lobe overflow. This has created an optically thick accretion disk around the secondary star in the system as well as bipolar outflows. Despite being the more evolved star, the primary is now the less massive component (originally approximately 9 solar masses, now approximately 3, De Greve & Linnell 1994). In 2012, my collaborators and I discovered that a hot spot has formed on the edge of the accretion disk due to the mass stream impacting the disk using spectropolarimetric data (Lomax et al. 2012).

More recent modeling work by Mennickent & Djurasevic (2013) required a hot spot at the same location that we detected one to reproduce beta Lyrae's light curve. In addition, their hot spot size is consistent with the size we derived from our spectropolarimetric observations. However, it is still not clear how common hot spots are amongst similar systems where the mass loser is an evolved star and the mass gainer is on the main sequence. Therefore, my collaborators and I are actively obtaining new observations of other beta Lyrae-like systems to determine if the hot spot-disk geometry is unique to beta Lyrae or if other binaries display a similar morphology.