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Session 22 - Binary Stars: New Generation Modeling Developments & Results.
Oral session, Tuesday, June 10
North Main Hall F/G,
Light curve model work has increasingly been extending into general observables. It now includes (or soon will) polarimetry, line profiles, pulse arrival times, and interferometric observations in addition to brightness and radial velocity. The inclusion criterion for the above-listed observation types is not that every one require a physical binary star model, but only that any combinations that are fitted simultaneously involve a physical model. Thus ordinary pulse arrival time analysis involves only the geometry of orbiting point sources, but can involve physical models when combined with light curves and radial velocities. Solution of combined light and velocity observations, although not yet common, is becoming more frequent. Models now have circumstellar disks, stellar atmospheres, and attenuation by circumstellar gas and dust in addition to basic external physical attributes such as tides, reflection, orbital eccentricity, and non-synchronous rotation. Some aspects of the pulse arrival time, line profile, and circumstellar attenuation problems will be discussed here. The pulse discussion centers on an algorithm through which differential corrections solutions can be carried out, including designation of the independent variable and formation of partial derivatives of arrival time with respect to model parameters. The profile discussion focusses on generalization of a binning procedure so as to include various broadening mechanisms and on computational strategies to improve accuracy. The attenuation discussion concerns efficient computation of attenuation in matter of arbitrary optical thickness with effective inclusion of several scattering and absorption mechanisms, arbitrary spatial distribution, and proper wavelength dependence.
