Characteristics of exoplanet host stars

Abundances and kinematics of exoplanetary systems

The aim of the project is to understand the formation and the evolution of exoplanetary systems using chemical elements as tracers. The currently known stars with plantes are metal-rich when compared with non-planetary hosts. This observational fact represents the only known link between the presence of planets and the stellar photospheric abundance of Fe. We propose to observe and analyse newly discovered planetary systems and the few hundreds expected to be discovered in next 3 to 5 years by Geneva exoplanet surveys in the framework of an established collaboration with Prof. Michel Mayor and his group. We shall perform unbiased and uniform comparison between stars with and without planetary mass companions in avolume limited sample in order to clarify the following issues:

• Why the stars wich host giant planets in nearby orbits are metal-rich?. Is this a primordial effect or is it caused by planet accretion?
• Planet host stars are expected to have different angular momentum history when compared with single stars. This effect together with a planet accretion process and tidal interactions may modify the atmospheric abundances of the light elements Li nad Be. We shall investigate this problem
• The ⁶Li/⁷Li isotopic ratio in the atmospheres of many planet hosts will be analysed in order to study processes of planetary migration and accretion
• According to some views, the formation of planetary systems can be triggered by supernova shocks which pollute the protostellar clouds by various products of the supernova nucleosynthesis. We shall study this scenario by performing an homogeneous abundance analysis of the alpha-, Fe-group, r- and s-process elements
• For a comprehensive view of the characteristics of exoplanetary systems, we shall follow up our targets with CanariCam attached to the 10.4 m - Gran Telescopio Canarias, attempting to find more giant planets at distant orbits which cannot be detected with current radial velocity techniques

The key physical processes operating in planetary systems will be identified by studying various trends in abundances of chemical elements of different origin with planetary mass, period and eccentricity.

Our refereed publications

Are beryllium abundances anomalous in stars with giant planets?
Santos, N. C.; Israelian, G.; López, R. J García; Mayor, M.; Rebolo, R.; Randich, S.; Ecuvillon, A.; Cerdeña, C. Domínguez
2004, A&A, in press. (astro-ph/0408108)

C, S, Zn and Cu abundances in planet-harbouring stars
Ecuvillon, A.; Israelian, G.; Santos, N. C.; Mayor, M.; Villar, V.; Bihain, G.
2004, A&A, in press. (astro-ph/0406584)

Nitrogen abundances in planet-harbouring stars
Ecuvillon, A.; Israelian, G.; Santos, N. C.; Mayor, M.; García López, R. J.; Randich, S.
2004, A&A, 418, 703

Spectroscopic [Fe/H] for 98 extra-solar planet-host stars. Exploring the probability of planet formation
Santos, N. C.; Israelian, G.; Mayor, M.
2004, A&A, 415, 1153

Lithium in stars with exoplanets
Israelian, G.; Santos, N. C.; Mayor, M.; Rebolo, R.
2004, A&A, 414, 601

New measurement of the ⁶Li/⁷Li isotopic ratio in the extra-solar planet host star HD 82943 and line blending in the Li 6708 Å region
Israelian, G.; Santos, N. C.; Mayor, M.; Rebolo, R.
2003, A&A, 405, 753

Statistical properties of exoplanets. II. Metallicity, orbital parameters, and space velocities
Santos, N. C.; Israelian, G.; Mayor, M.; Rebolo, R.; Udry, S.
2003, A&A, 398, 363

Beryllium abundances in stars hosting giant planets
Santos, N. C.; García López, R. J.; Israelian, G.; Mayor, M.; Rebolo, R.; García-Gil, A.; Pérez de Taoro, M. R.; Randich, S.
2002, A&A, 386, 1028

Planet accretion and the abundances of lithium isotopes
Montalbán, J.; Rebolo, R.
2002, A&A, 386, 1039

The metal-rich nature of stars with planets
Santos, N. C.; Israelian, G.; Mayor, M.
2001, A&A, 373, 1019

Evidence for planet engulfment by the star HD 82943
Israelian, G.; Santos, N. C.; Mayor, M.; Rebolo, R.
2001, Nature, 411, 163

Chemical analysis of 8 recently discovered extra-solar planet host stars
Santos, N. C.; Israelian, G.; Mayor, M.
2000, A&A, 363, 228

Beryllium abundances in parent stars of extrasolar planets: 16 Cygni A & B and rho¹ Cancri
García López, R. J.; Pérez de Taoro, M. R.
2000, A&A, 334, 599