1. IRAP-UMR 5277; CNRS & Univ. de Toulouse; 14 Av. E. Belin; F-31400; Toulouse; France
2. California Institute of Technology; MC 249-17; Pasadena; CA; 91125; USA
3. Departamento de Fìsica-ICEx-UFMG; Av. Antônio Carlos; 6627; 30270-901; Belo Horizonte; MG; Brazil
4. ESO; Karl-Schwarzschild-Str. 2; D-85748; Garching; Germany
5. IPAG-UMR 5274; CNRS & Univ. J. Fourier; 414 rue de la Piscine; F-38041; Grenoble; France
6. School of Physics and Astronomy; University of St Andrews; St Andrews; KY16 9SS
7. Department of Astronomy; Cornell University; Ithaca; NY; 14853-6801; USA