CoRoT light curves of RR Lyrae stars CoRoT 101128793 : long-term changes in the Blazhko effect and excitation of additional modes

The CoRoT (Convection, Rotation and planetary Transits) space mission provides a valuable opportunity to monitor stars with uninterrupted time sampling for up to 150 days at a time. The study of RR Lyrae stars, performed in the framework of the Additional Programmes belonging to the exoplanetary field, will particularly benefit from such dense, long-duration monitoring. Aims. The Blazhko effect in RR Lyrae stars is a long-standing, unsolved problem of stellar astrophysics. We used the CoRoT data of the new RR Lyrae variable CoRoT 101128793 (f(0) = 2.119 d(-1), P = 0.4719296 d) to provide us with more detailed observational facts to understand the physical process behind the phenomenon. Methods. The CoRoT data were corrected for one jump and the long-term drift. We applied different period-finding techniques to the corrected timeseries to investigate amplitude and phase modulation. We detected 79 frequencies in the light curve of CoRoT 101128793. They have been identified as the main frequency f(0) and its harmonics, two independent terms, the terms related to the Blazhko frequency f(m), and to several combination terms. Results. A Blazhko frequency f(m) = 0.056 d(-1) and a triplet structure around the fundamental radial mode and harmonics were detected, as were a long-term variability on the Blazhko modulation. Indeed, the amplitude of the main oscillation is decreasing along the CoRoT survey. The Blazhko modulation is one of the smallest observed in RR Lyrae stars. Moreover, the additional modes f(1) = 3.630 and f(2) = 3.159 d(-1) are detected. Taking its ratio with the fundamental radial mode into account, the term f(1) could be the identified as the second radial overtone. Detecting of these modes in horizontal branch stars is a new result obtained by CoRoT.

Language

English

Source (journal)

Astronomy and astrophysics. - Berlin, 1969, currens

Related dataset(s)

CoRoT 101128793 light curves / Poretti, E. - -, 2010

Publication

Berlin : Springer , 2010

ISSN

0004-6361 [print]

1432-0746 [online]

DOI