Images of Gravitational and Magnetic Phenomena Derived from 2D Back-Projection Doppler Tomography of Interacting Binary Stars

Abstract

We have used 2D back-projection Doppler tomography as a tool to examine the influence of gravitational and magnetic phenomena in interacting binaries which undergo mass transfer from a magnetically-active star onto a non-magnetic main sequence star. This multi-tiered study of over 1300 time-resolved spectra of 13 Algol binaries involved calculations of the predicted dynamical behavior of the gravitational flow and the dynamics at the impact site, analysis of the velocity images constructed from tomography, and the influence on the tomograms of orbital inclination, systemic velocity, orbital coverage, and shadowing. The H$\alpha$ tomograms revealed eight sources: chromospheric emission, a gas stream along the gravitational trajectory, a star-stream impact region, a bulge of absorption or emission around the mass-gaining star, a Keplerian accretion disk, an absorption zone associated with hotter gas, a disk-stream impact region, and a hot spot where the stream strikes the edge of a disk. We described several methods used to extract the physical properties of the emission sources directly from the velocity images, including S-wave analysis, the creation of simulated velocity tomograms from hydrodynamic simulations, and the use of synthetic spectra with tomography to sequentially extract the separate sources of emission from the velocity image. In summary, the tomography images have revealed results that cannot be explained solely by gravitational effects: chromospheric emission moving with the mass-losing star, a gas stream deflected from the gravitational trajectory, and alternating behavior between stream state and disk state. Our results demonstrate that magnetic effects cannot be ignored in these interacting binaries.

arXiv comment18 pages, 4 tables, 12 figures; Astrophysical Journal, Vol. 794 (October 20, 2014)

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• Doppler tomography of the Double Periodic Variable HD 170582 at low and high stage
• Model for the long and orbital brightness variability of the $\beta$ Lyrae type binary OGLE-BLG-ECL-157529
• Evidence of active regions in the donor of the Algol-type binary V393 Scorpii and test for the dynamo model of its long cycle
• HD 63021: Chromospheric Activity and Mass Transfer in a Close Binary
• Spectroscopic long-term monitoring of RZ Cas -- Part I: Basic stellar and system parameters