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|Title:||CoRoT space photometry of seven Cepheids||Authors:||PORETTI, Ennio
Le Borgne, J. F.
Benkő, J. M.
Weiss, W. W.
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||454||Issue:||1||First Page:||849||Abstract:||A few Galactic classical Cepheids were observed in the programmes of space missions as Coriolis, MOST, and Kepler. An appealing opportunity was to detect additional non-radial modes, thus opening the possibility to perform asteroseismic studies and making the pulsational content of Galactic Cepheids more similar to that of Magellanic Clouds ones. However, only hints of cycle-to-cycle variations were found, without any strict periodicity. In this context the potential of the CoRoT exoplanetary data base was not fully exploited despite the wide area covered on the Galactic plane. Therefore, we investigated all the candidate Cepheids pointed out by the automatic classification of the CoRoT curves. At the end, we could identify seven bona fide Cepheids. The light curves were investigated to remove some instrumental effects. The frequency analysis was particularly delicate since these small effects can be enhanced by the large amplitude, resulting in the presence of significant, but spurious, peaks in the power spectrum. Indeed, the careful evaluation of a very attracting peak in the spectra of CoRoT 0102618121 allowed us to certify its spurious origin. Once that the instrumental effects were properly removed, no additional mode was detected. On the other hand, cycle-to-cycle variations of the Fourier parameters were observed, but very small and always within ±3σ. Among the seven Cepheids, there are two Pop. I first-overtone pulsators, four Pop. I fundamental mode pulsators, and one Pop. II star. The CoRoT colours allowed us to measure that times of maximum brightness occur a little earlier (about 0.01 period) at short wavelengths than at long ones.||Acknowledgments:||The CoRoT space mission has been developed and operated by CNES, with contributions from Austria, Belgium, Brazil, ESA (RSSD and Science Program), Germany, and Spain. The authors thank the anonymous referee for useful comments. EP acknowledges Observatoire Midi-Pyrénées for the two-months grant allocated between 2014 May and July; useful discussions with Boris Dintrans and Pascal Fouqué at the very beginning of the project are acknowledged. JMB thanks for the support of the NKFIH Grant K-115709. MR acknowledges financial support from the FP7 project ‘SpaceInn: Exploitation of Space Data for Innovative Helio- and Asteroseismology’, EP acknowledges PRIN-INAF 2014 Galactic Archaelogy for support to latest activities. This research has made use of the ExoDat Database, operated at LAM-OAMP, Marseille, France, on behalf of the CoRoT /Exoplanet program. The present study has used the SIMBAD data base operated at the Centre de Données Astronomiques (Strasbourg, France). This work is partially based on observations collected at La Silla Observatory, ESO (Chile) with the HARPS spectrograph at the 3.6-m telescope under programme LP185.D-0056.||URI:||http://hdl.handle.net/20.500.12386/23286||URL:||https://academic.oup.com/mnras/article/454/1/849/1121288||ISSN:||0035-8711||DOI:||10.1093/mnras/stv1899||Bibcode ADS:||2015MNRAS.454..849P||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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