The Period Changes of the Cepheid RT Aurigae
Abstract
Observations of the light curve for the 3.7-day Cepheid RT Aur both before and since 1980 indicate that the variable is undergoing an overall period increase, amounting to +0.082 +-0.012 s/yr, rather than a period decrease, as implied by all observations prior to 1980. Superposed on the star's O-C variations is a sinusoidal trend that cannot be attributed to random fluctuations in pulsation period. Rather, it appears to arise from light travel time effects in a binary system. The derived orbital period for the system is P = 26,429 +-89 days (72.36 +-0.24 years). The inferred orbital parameters from the O-C residuals differ from those indicated by existing radial velocity data. The latter imply the most reasonable results, namely a1 sin i = 9.09 (+-1.81) x 10^8 km and a minimum secondary mass of M2 = 1.15 +-0.25 Msun. Continued monitoring of the brightness and radial velocity changes in the Cepheid are necessary to confirm the long-term trend and to provide data for a proper spectroscopic solution to the orbit.
Keywords
Cite
@article{arxiv.0709.3085,
title = {The Period Changes of the Cepheid RT Aurigae},
author = {David G. Turner and Ivan S. Bryukhanov and Igor I. Balyuk and Alexey M. Gain and Roman A. Grabovsky and Valery D. Grigorenko and Igor V. Klochko and Attila Kosa-Kiss and Alexey S. Kosinsky and Ivan J. Kushmar and Vyacheslav T. Mamedov and Natalya A. Narkevich and Andrey J. Pogosyants and Andrey S. Semenyuta and Ivan M. Sergey and Vladimir V. Schukin and Jury B. Strigelsky and Valentina G. Tamello and David J. Lane and Daniel J. Majaess},
journal= {arXiv preprint arXiv:0709.3085},
year = {2009}
}
Comments
Accepted for publication in PASP (November 2007)