Journal Article

The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

Á. Sódor, G. Hajdu, J. Jurcsik, B. Szeidl, K. Posztobányi, Zs. Hurta, B. Belucz and E. Kun

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 427, issue 2, pages 1517-1529
Published in print December 2012 | ISSN: 0035-8711
Published online December 2012 | e-ISSN: 1365-2966 | DOI:
The light-curve modulation of XY And and UZ Vir: two Blazhko RR Lyrae stars with additional frequencies

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We present a thorough analysis of multicolour CCD observations of two modulated RRab-type variables, XY And and UZ Vir. These Blazhko stars show relatively simple light-curve modulation with the usual multiplet structures in their Fourier spectra. One additional, independent frequency with linear-combination terms of the pulsation frequency is also detected in the residual spectrum of each of the two stars. The amplitude and phase relations of the triplet components are studied in detail. Most of the epoch-independent phase differences show a slight, systematic colour dependence. However, these trends have opposite signs in the two stars. The mean values of the global physical parameters and their changes with the Blazhko phase are determined, utilizing the inverse photometric method (IPM). The modulation properties and the IPM results are compared for the two variables. The pulsation period of XY And is the shortest when its pulsation amplitude is the highest, while UZ Vir has the longest pulsation period at this phase of the modulation. Despite this contrasting behaviour, the phase relations of the variations in their mean physical parameters are similar. These results do not agree with the predictions of the Blazhko model of Stothers.

Keywords: techniques: photometric; stars: horizontal branch; stars: individual: XY And; stars: individual: UZ Vir; stars: oscillations; stars: variables: RR Lyrae

Journal Article.  7960 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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