J. Budaj, B. Miller, M.T. Richards (PennState), P. Koubsky (Astron. Inst., Ondrejov, Czech Republic)
The physical properties of circumstellar material in interacting binaries are still not very well understood. We have used a new spectrum synthesis code called SHELLSPEC to calculate the optical and ultraviolet spectra of TT Hya, an Algol-type eclipsing interacting binary. The synthetic spectra include the contributions from the stars and the accretion disk surrounding the primary. The optical spectra in the H-alpha region were modeled and Doppler tomograms were made from the modeled spectra to demonstrate the good match between the observed and synthetic spectra. The tomography of the observed H-alpha profiles confirmed the presence of the accretion disk while the tomography of the difference spectra (after substracting the synthetic spectra of the stars and a disk) revealed a gas stream. The optical spectra also provided new precise radial velocities of the primary and secondary stars and enabled us to improve significantly the orbital and absolute dimensions of the system. The new orbital solution suggests a small, but significant, eccentricity of the binary orbit. The synthetic and observed IUE spectra were also compared. The ultraviolet spectra are dominated by the iron curtain features and comparison with the synthetic spectra enabled us to estimate characteristic temperatures of the accretion disk and explain quantitatively the formation of the UV spectra.
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The author(s) of this abstract have provided an email address for comments about the abstract: budaj@astro.psu.edu
Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.