Bibcode
Adibekyan, V. Zh.; Benamati, L.; Santos, N. C.; Alves, S.; Lovis, C.; Udry, S.; Israelian, G.; Sousa, S. G.; Tsantaki, M.; Mortier, A.; Sozzetti, A.; De Medeiros, J. R.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 450, Issue 2, p.1900-1915
Fecha de publicación:
6
2015
Número de citas
27
Número de citas referidas
24
Descripción
We performed a uniform and detailed abundance analysis of 12 refractory
elements (Na, Mg, Al, Si, Ca, Ti, Cr, Ni, Co, Sc, Mn, and V) for a
sample of 257 G- and K-type evolved stars from the CORALIE planet search
programme. To date, only one of these stars is known to harbour a
planetary companion. We aimed to characterize this large sample of
evolved stars in terms of chemical abundances and kinematics, thus
setting a solid base for further analysis of planetary properties around
giant stars. This sample, being homogeneously analysed, can be used as a
comparison sample for other planet-related studies, as well as for
different type of studies related to stellar and Galaxy astrophysics.
The abundances of the chemical elements were determined using an local
thermodynamic equilibrium (LTE) abundance analysis relative to the Sun,
with the spectral synthesis code MOOG and a grid of Kurucz ATLAS9
atmospheres. To separate the Galactic stellar populations, both a purely
kinematical approach and a chemical method were applied. We confirm the
overabundance of Na in giant stars compared to the field FGK dwarfs.
This enhancement might have a stellar evolutionary character, but
departures from LTE may also produce a similar enhancement. Our chemical
separation of stellar populations also suggests a `gap' in metallicity
between the thick-disc and high-α metal-rich stars, as previously
observed in dwarfs sample from HARPS. The present sample, as most of the
giant star samples, also suffers from the B - V colour cut-off, which
excludes low-log g stars with high metallicities, and high-log g star
with low [Fe/H]. For future studies of planet occurrence dependence on
stellar metallicity around these evolved stars, we suggest to use a
subsample of stars in a `cut-rectangle' in the log g-[Fe/H] diagram to
overcome the aforementioned issue.
Proyectos relacionados
Pruebas Observacionales de los Procesos de Nucleosíntesis en el Universo
Recientemente se han llevado a cabo varios análisis espectroscópicos de estrellas con planetas. Uno de los resultados más relevantes ha sido descubrir que las estrellas con planetas son en promedio más metálicas que las estrellas del mismo tipo espectral sin planetas conocidos (Santos, Israelian & Mayor 2001, A&A, 373, 1019; 2004, A&A, 415, 1153)
Garik
Israelian