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Issue A&A Volume 369, Number 1, April I 2001 Page(s) 65 - 73 Section Galactic structure and dynamics DOI 10.1051/0004-6361:20010100

A&A 369, 65-73 (2001)
DOI: 10.1051/0004-6361:20010100

New determination of the solar apex

Ch. Fehrenbach^{1, 2}, M. Duflot¹ and R. Burnage<sup>2

1</sup>  Observatoire de Marseille, 2 place Le Verrier, 13248 Marseille Cedex 04, France
²  Observatoire de Haute Provence, 04870 Saint Michel l'Observatoire, France

(Received 4 August 2000 / Accepted 16 November 2000 )

Abstract
Many studies recently have been performed to determine the velocity vector of the Sun, mainly using the latest data on proper motions and parallaxes given by the Hipparcos satellite. We wished to carry out a similar study using totally independent data: the numerous radial velocities (RV) obtained with the Fehrenbach Objective Prisms (PO). This method allows the determination of the RVs of all the stars contained in the same field. These RVs are relative to each other but are linked to the IAU standard system by means of at least two calibration stars of known RV belonging to that field. These data are very homogeneous. We discuss the precision of the results, and deduce that this material is relevant for the computation of the movement of the Sun towards its Apex. We have performed several studies: 1) With 6965 stars of magnitudes ranging from 7 to 10, measured with the small PO of 15 cm diameter (PPO), with the whole sample and with the same sample split into blue and red stars. 2) With 11 978 stars of magnitudes ranging from 7 to 11, by adding to the previous sample the stars measured with the 60 cm diameter PO associated with the Schmidt telescope of Observatoire de Haute Provence (SPO). The results of both studies are consistent. 3) We have estimated the distance D of all stars studied and determined U, V, W and S for four groups of stars selected according to their distances: D< 100, 100< D< 300, 300< D< 500, D> 500 parsecs. We have determined the variation of U, V, W and S with respect to the distance of the stars. The variation of U, V and S is linear up to 500 parsecs. We can consider that W is constant.

Key words: Galaxy: structure -- stars: kinematics -- techniques: radial velocity

Offprint request: M. Duflot, duflot@observatoire.cnrs-mrs.fr

© ESO 2001

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