The Origin of Warped, Precessing Disks in X-Ray Binaries

The radiation-driven warping instability discovered by Pringle holds considerable promise as the mechanism responsible for producing warped, precessing accretion disks in X-ray binaries. This instability is an inherently global mode of the disk, thereby avoiding the difficulties with earlier models for the precession. Here we follow up earlier work to study the linear behavior of the instability in the specific context of a binary system. We treat the influence of the companion as an orbit-averaged, quadrupole torque on the disk. The presence of this external torque allows the existence of solutions in which the direction of precession of the warp is retrograde with respect to disk rotation, in addition to the prograde solutions which exist in the absence of external torques.Comment: 12 pages, 3 figure

Letter from Philip Mitchell to Christine Smith; December 22, 1941

From the Ellard-Murphree-Pilgreen-Smith Family Papers Collection. Letter from Philip Mitchell discussing his travel to and at marine training in Paris Island, SC.https://athenacommons.muw.edu/smithpapers/1177/thumbnail.jp

Letter from Philip Mitchell to Christine Faust; September 3, 1944

Philip tells how a bullet wound damaged his throat and how he was abe to handle the crisis. He appreciates the atmosphere of the hospital. He congratulates Christine on her marriage.https://athenacommons.muw.edu/smithpapers/1443/thumbnail.jp

Letter from Philip Mitchell to Christine Smith; December 03, 1941

From the Ellard-Murphree-Pilgreen-Smith Family Papers Collection. Letter from Philip Mitchell to Christine Smith; December 3, 1941. Phil Mitchell writes about his new job, visiting with Christine, and plans for the winter holiday.https://athenacommons.muw.edu/smithpapers/1173/thumbnail.jp