Debris disk and exoplanets: The metallicity problem

CHAVERO, C.; DE LA REZA, R.; GOMÉZ, M.

Pucón-Chile

Congreso; XI Reunion Regional Latinoamericana de Astronomia; 2005

Sociedad Chilena de Astronomía

Debris disks (DD) are the most visible signposts of other planetary systems, representing indirect evidence of planetary system formation. It has recently been shown that the metallicity distribution of the stars with planets peaks at a more positive value than for nearby stars. Our aim is to test whether the metallicity differentiates DD stars from stars with Doppler detected planetary mass objects. We compiled a list of 140 DD candidates stars from the literature. We obtained photometry data from the IRAS and Hipparcos databases. We used the catalog of Nordström et al. (2004) to obtain metallicity for F and G stars. With the data from the IRAS databases we constructed the IRAS Color- Color diagram, the compiled sample shows clear color excesses. We find an anti-correlation between the age and the IR excess for the DD stars with resolved disk . It means more age, less IR excess. Finally, we compare the metallicity distributions of F and G DD candidate stars, Exoplanet host stars and field main sequence stars, and find that F-G DD objects have metallicities quite similar (although not identical) to field main sequence stars and significantly different from the Exoplanet host group. This result may suggest that giant planets of the type detected by radial velocity techniques are not as common in Vega-like objects as in Exoplanet Host Stars.