VLT multi-epoch radial velocity survey toward NGC 6253. Analysis of three transiting planetary candidates - Astrophysics > Astrophysics of GalaxiesReportar como inadecuado




VLT multi-epoch radial velocity survey toward NGC 6253. Analysis of three transiting planetary candidates - Astrophysics > Astrophysics of Galaxies - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We measured the radial velocity of 139 stars in the region of NGC 6253,discussing cluster-s membership and binarity in this sample, complementing ouranalysis with photometric, proper motion, and radial velocity data availablefrom previous studies of this cluster, and analyzing three planetary transitingcandidates we found in the field of NGC 6253. Spectra were obtained with theUVES and GIRAFFE spectrographs at the VLT, during three epochs in August 2008.The mean radial velocity of the cluster is -29.11+-0.85 km-s. Using bothradial velocities and proper motions we found 35 cluster-s members, among which12 are likely cluster-s close binary systems. One star may have a sub-stellarcompanion, requiring a more intensive follow-up. Our results are in goodagreement with past radial velocity and photometric measurements. Furthermore,using our photometry, astrometry and spectroscopy we identified a new sub-giantbranch eclipsing binary system, member of the cluster. The cluster-s closebinary frequency at 29% +- 9% 34% +-10% once including long periodbinaries, appears higher than the field binary frequency equal to 22% +- 5%,though these estimates are still consistent within the uncertainties. Among thethree transiting planetary candidates the brightest one V=15.26 is worth tobe more intensively investigated with higher percision spectroscopy. Wediscussed the possibility to detect sub-stellar companions brown dwarfs andplanets with the radial velocity technique both with UVES-GIRAFFE and HARPSaround turn-off stars of old open clusters abridged.



Autor: M. Montalto, S. Villanova, J. Koppenhoefer

Fuente: https://arxiv.org/







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