Letter to the Editor
A purely geometric distance to the binary star Atlas, a member of the Pleiades*
Laboratoire d'Astrophysique de l'EPFL, Observatoire, 1290 Chavannes-des-Bois, Switzerland e-mail: firstname.lastname@example.org
2 Observatoire de Genève, 1290 Sauverny, Switzerland
3 Laboratoire d'Astrophysique, Observatoire de Grenoble, 38041 Grenoble Cedex 9, France
4 Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium
5 European Southern Observatory, Casilla 19001, Santiago 19, Chile
Accepted: 26 August 2004
We present radial velocity and new interferometric measurements of the double star Atlas, which permit, with the addition of published interferometric data, to precisely derive the orbital parameters of the binary system and the masses of the components. The derived semi-major axis, compared with its measured angular size, allows to determine a distance to Atlas of pc in a purely geometrical way. Under the assumption that the location of Atlas is representative of the average distance of the cluster, we confirm the distance value generally obtained through main sequence fitting, in contradiction with the early Hipparcos result ( pc).
Key words: stars: individual: Atlas / stars: distances / stars: fundamental parameters / Galaxy: open clusters and associations: individual: Pleiades
Based on observations made with the ELODIE echelle spectrograph mounted on the 1.93-m telescope at the Observatoire de Haute-Provence (CNRS), with the FEROS echelle spectrograph mounted on the 2.2-m telescope at ESO-La Silla Observatory (programme No. 072.D-0235B), with the CORALIE echelle spectrograph mounted on the 1.2-m Euler Swiss telescope at ESO-La Silla Observatory, with the Naval Prototype Optical Interferometer (US Naval Observatory) and with the Mark iii stellar interferometer at Mt Wilson.
© ESO, 2004