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Is There Plenty of Metal-poor Stars with Planets in the Galactic Thick Disk?

V. Zh. Adibekyan, N. C. Santos, S. G. Sousa, G. Israelian, P. Figueira

We performed an uniform spectroscopic analysis of 1111 FGK dwarfs observed as part of the HARPS GTO planet search program. We applied a purely chemical approach, based on [α/Fe] ratio, to distinguish the various stellar components in the Galaxy. Apart from the well known Galactic thick and thin disks, we separated an α-enhanced stellar family at super-solar metallicities. The metal-rich high-α stars have orbits similar to the thin disk stars, but they are similar to thick disk stars in terms of age. Our data indicate that the incidence of stars with planets are greater among the chemically separated thick disk stars with [Fe/H] ≲ -0.3 dex than they are among thin disk stars in the same [Fe/H] interval. Our results allow us to suppose that a certain chemical composition, and not the Galactic birth place of the stars, is the causative factor for that.

New Quests in Stellar Astrophysics III: A Panchromatic View of Solar-like Stars, With and Without Planets
M. Chavez, E. Bertone, O. Vega, V. De la Luz

Astronomical Society of the Pacific
Volume 472, Page 117
2013 April

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