Journal Article

A new method for determining physical parameters of fundamental mode RR Lyrae stars from multicolour light curves

Á. Sódor, J. Jurcsik and B. Szeidl

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 1, pages 261-271
Published in print March 2009 | ISSN: 0035-8711
Published online March 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14262.x
A new method for determining physical parameters of fundamental mode RR Lyrae stars from multicolour light curves

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We present a new method for determining physical parameters of RRab variables exclusively from multicolour light curves. Our method is an inverse photometric Baade–Wesselink analysis which, using a non-linear least-squares algorithm, searches for the effective temperature (Teff) and pulsational velocity (Vp) curves and other physical parameters that best fit the observed light curves, utilizing synthetic colours and bolometric corrections from static atmosphere models. The Teff and Vp curves are initially derived from empirical relations then they are varied by the fitting algorithm. The method yields the variations and the absolute values of the radius, the effective temperature, the visual brightness and the luminosity of individual objects. Distance and mass are also determined. The method is tested on nine RRab stars subjected to Baade–Wesselink analyses earlier by several authors. The physical parameters derived by our method using only the light-curve data of these stars are well within their possible ranges defined by direct Baade–Wesselink and other techniques. A new empirical relation between the IC magnitude and the pulsational velocity is also presented, which allows to construct the Vp curve of an RRab star purely from photometric observations to an accuracy of about 3.5 km s−1.

Keywords: methods: data analysis; techniques: photometric; stars: horizontal branch; stars: oscillations; stars: variables: other

Journal Article.  6606 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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