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Paper: Eclipsing Binary Modeling Advances – Recent and On the Way
Volume: 435, Binaries – Key to Comprehension of the Universe
Page: 45
Authors: Wilson, R. E.; Van Hamme, W.
Abstract: Several recent departures from tradition in EB models demonstrate increased capability to extract information from observations. In one area, model light curves in absolute flux are matched to observed absolute flux curves to find distances and their uncertainties in a straightforward, one step process called Direct Distance Estimation (DDE) that works well for all morphological types. Eclipsing binaries (EB's) can yield distances as accurate as the better parallax distances for much more remote objects. Comparisons with Hipparcos parallax distances are illustrated for 10 binaries. Published absolute flux calibrations can be supplemented by inverse application of the DDE algorithm to EB's with accurately known distances, and weak EB and ellipsoidal variable solutions can be strengthened in inverse DDE solutions where distances and extinctions are accurately known. A temperature-distance (T–d) theorem guards against over-determined and under-determined solutions and has been generalized to include interstellar extinction (T–d–A theorem). Dependence of derived distance on calibration accuracy, in the presence of interstellar extinction, is investigated here. Simulations showed fast and reliable convergence while recovering known extinction from synthetic light curves in widely separated bands. Conversion from spectroscopic to mean global temperature is now rigorously computable if the spectroscopic observation time is known. We derive even greater distance to D33 J013346.2+304439.9 in M33 than did Bonanos, which already was greater than 11 previous estimates from various indicators, and discuss possible reasons for the disparity. In another area, pulsation and EB analyses are being unified to exploit the growing lists of EB’s that show pulsations. Our interest is in coherent pulsation/EB\ models in which stars actually pulsate geometrically and thermally, and in impersonal solutions that yield standard errors. For now we apply only a phenomenological model so as to gain experience. Pulsation-related output consists of radius, R(t), and temperature, T(t), waveforms and a pulsation ephemeris. Procedural alternatives are discussed. Some other ideas that could lead to progress are briefly mentioned.
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