Date of Award
Physics and Astronomy
Jennifer L. Hoffman, Ph.D.
Binary Systems, Mass Loss, Mass Transfer
The majority of massive stars are members of binary systems. In order to have a better understanding of their evolutionary pathways, the mass and angular momentum loss from massive binaries needs to be well understood. Self consistent explanations for their behavior need to be valid across many wavelength regimes in order to illuminate key phases of mass loss to completely determine how it affects their evolution. In this dissertation I present the results of X-ray and specropolarimetric studies on one Roche-lobe overflow binary (β Lyr) and two colliding wind binaries (V444 Cyg and WR 140).
In β Lyr a repeatable discrepancy between the secondary eclipse in total and polarized light indicates that an accretion hot spot has formed on the edge of the disk in the system. This hot spot may also be the source of the bipolar outflows within the system. The existence of a hot spot and its relationship to bipolar outflows is important in understanding the mass transfer dynamics of Roche-lobe overflow binaries.
The absorption of the 2.0 keV spectral fit component in V444 Cyg suggests that the shock has a large opening angle while analysis of the X-ray light curves places the stagnation point farther away from the O star than theoretically expected. Combining this with evidence of polarimetric variability in V444 Cyg's optical emission lines shows that the effects of radiative inhibition or braking are significant for this close binary and may be important in other colliding wind systems.
Long term X-ray monitoring of the shock formed by the winds in WR 140 shows conflicting evidence for unexpected intrinsic hard X-ray emission. Spectral analysis shows that the low energy thermal tail is causing the observed higher energy emission. On the other hand, light curve analysis of the absorption feature near periastron passage suggests that there may be intrinsic hard X-ray emission from the system. WR 140's polarimetric behavior is consistent with the formation of dust near periastron passage, better polarimetric monitoring of the system is needed.
The work presented in this dissertation is one small step toward a better understanding of the processes involved in mass loss in binary systems. Continued studies of these three objects, in addition to other important systems, will provide important new constraints on the mass loss structures that influence the future evolution of massive binary systems.
Lomax, Jamie Renae, "The X-ray and Spectropolarimetric View of Mass Loss and Transfer in Massive Binary Stars" (2013). Electronic Theses and Dissertations. 862.
Received from ProQuest
Jamie Renae Lomax