Searches around young nearby stars

neighbours in our solar neighbourhood

Jovian-mass substellar objects are known to be orbiting stars in the solar neighborhood (Mayor and Queloz 1995; Marcy and Butler 1996). High precision radial velocity measurements have shown the existence of giant planets with masses similar to Jupiter around more than 100 nearby stars. About five per cent of solar-type stars appear to have such planets. The Doppler technique has favored detection of planets in a range of orbital semimajor axis from 0.04 to 4 AU. The generally small angular separation and large luminosity contrast with the parent star have precluded direct imaging and spectroscopy of these objects. Except for the eclipsing planet around the star HD 209458 (Charbonneau et al. 2000), there is a lack of direct measurements of the planetary atmospheres and our knowledge of their physical conditions is rather limited. Direct imaging of giant planets should bring a wealth of information on these planets and is thus an important goal for the new generation of very large diameter telescopes like the Gran Telescopio Canarias.

Direct imaging of cool giant planets is an enormous challenge. The large luminosity contrast of a jupiter analogue with respect a solar-type parent star (larger than 109 in the visible) makes direct imaging of these bodies extremely difficult. However, the contrast is much smaller in the mid-infrared (106) and a 10 m telescope equipped with a mid-IR camera should be able to image them.

Our group detected the first L-spectral-type confirmed brown dwarf around a star (Rebolo et al. 1998), and it is still one of the least massive brown dwarfs as companions to stars (about 25 MJup).

Our refereed publications

New neighbours. III. 21 new companions to nearby dwarfs, discovered with adaptive optics
Beuzit, J.-L.; Ségransan, D.; Forveille, T.; Udry, S.; Delfosse, X.; Mayor, M.; Perrier, C.; Hainaut, M.-C.; Roddier, C.; Roddier, F.; Martín, E. L.
2004, A&A, 425, 997

A CCD imaging search for wide metal-poor binaries
Zapatero Osorio, M. R.; Martín, E. L.
2004, A&A, 419, 167

Discovery of a Low-Mass Brown Dwarf Companion of the Young Nearby Star G 196-3
Rebolo, Rafael; Zapatero Osorio, María R.; Madruga, Santiago; Béjar, Víctor J. S.; Arribas, Santiago; Licandro, Javier
1998, Sci, 282, 1309

Previous refereed publications

Lithium in the pre-main sequence triple system UX Tauri
Magazzu, A.; Martin, E. L.; Rebolo, R.
1991, A&A, 249, 149