Reference : Oscillating blue stragglers, gamma Doradus stars and eclipsing binaries in the open clus...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
http://hdl.handle.net/2268/75437
Oscillating blue stragglers, gamma Doradus stars and eclipsing binaries in the open cluster NGC 2506
English
Arentoft, T. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark ; Danish AsteroSeismology Centre, University of Aarhus, 8000 Aarhus C., Denmark]
De Ridder, J. [Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium]
Grundahl, F. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark; Danish AsteroSeismology Centre, University of Aarhus, 8000 Aarhus C., Denmark]
Glowienka, L. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark]
Waelkens, C. [Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium]
Dupret, Marc-Antoine [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique stellaire théorique >]
Grigahcène, A. [GRAAG, Algiers Observatory, BP 63 Bouzareah, 16340 Algiers, Algeria]
Lefever, K. [Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium]
Jensen, H. R. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark]
Reyniers, M. [Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium]
Frandsen, S. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark; Danish AsteroSeismology Centre, University of Aarhus, 8000 Aarhus C., Denmark]
Kjeldsen, H. [Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C., Denmark; Danish AsteroSeismology Centre, University of Aarhus, 8000 Aarhus C., Denmark]
1-Apr-2007
Astronomy and Astrophysics
EDP Sciences
465
965-979
Yes (verified by ORBi)
International
0004-6361
1432-0746
Les Ulis
France
[en] stars: blue stragglers ; stars: variables: delta Sct ; gamma Dor ; stars: binaries: eclipsing ; galaxies: open clusters and associations: individual: NGC 2506 ; techniques: photometric
[en] Context: This is the first step in a project to combine studies of eclipsing binaries and oscillating stars to probe the interior of Blue Stragglers (BS). This may imply a way to discriminate observationally between different birth mechanisms of BS stars. Aims: We study the open cluster NGC 2506 which contains oscillating BS stars and detached eclipsing binaries for which accurate parameters can be derived. This will tightly constrain the cluster isochrone and provide an absolute mass, radius and luminosity-scale for the cluster stars along with the cluster age, metallicity and distance. The present work focuses on obtaining the light curves of the binaries and determine their orbital periods, on obtaining power spectra of the oscillating BS stars to select targets for follow-up studies, and on searching for gamma Doradus type variables which are also expected to be present in the cluster. Methods: With a two-colour, dual-site photometric campaign we obtained 3120 CCD-images of NGC 2506 spread over four months. We analysed the BI time-series of the oscillating stars and used simulations to derive statistical uncertainties of the resulting frequencies, amplitudes and phases. A preliminary mode-identification was performed using frequency ratios for the oscillating BS stars, and amplitude ratios and phase differences for a population of newly detected gamma Doradus stars. Results: We quadrupled the number of known variables in NGC 2506 by discovering 3 new oscillating BS stars, 15 gamma Doradus stars and four new eclipsing binaries. The orbital periods of 2 known, detached eclipsing binaries were derived. We discovered a BS star with both p-mode and g-mode variability and we confronted our gamma Doradus observations with state-of-the-art seismic models, but found significant discrepancy between theory and observations. Conclusions: . NGC 2506 is an excellent target for asteroseismic tests of stellar models, as strong external constraints can be imposed on the models of a population of more than 20 oscillating stars of different types. Based on observations obtained at the Flemish Mercator telescope on La Palma, Spain, the Danish 1.5-m telescope at ESO, La Silla, Chile, and on observations collected at the European Southern Observatory, Paranal, Chile (ESO Programme 075.D-0206(B)). Catalog of individual photometry measurements for all variables is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/465/965
http://hdl.handle.net/2268/75437
10.1051/0004-6361:20066931
http://adsabs.harvard.edu/abs/2007A%26A...465..965A
http://de.arxiv.org/abs/astro-ph/0703111

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