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Astron. Astrophys. 335, L61-L64 (1998)

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Letter to the Editor

Evidence for a signature of the galactic bar in the solar neighbourhood *

D. Raboud, M. Grenon, L. Martinet, R. Fux and S. Udry

Observatoire de Genève, CH-1290 Sauverny, Switzerland

Received 19 February 1998 / Accepted 14 May 1998


Using available kinematical data for a subsample of NLTT stars from the HIPPARCOS mission we confirm the existence of a previously reported local anomaly in the [FORMULA] plane: the mean motion [FORMULA] for old disc stars, with [FORMULA] km s-1, is largely positive ([FORMULA] km s-1 w.r.t. the Galactic Center).

With the use of the newest global self-consistent numerical models of our Galaxy (Fux 1997), we show that a bar could be responsible for this observed velocity anomaly. A fraction of our stars have bar perturbed "hot" orbits, allowing them to erratically wander from inside the bar to regions outside the corotation, in particular through the solar neighbourhood.

Key words: Galaxy: structure, kinematics and dynamics

* Based on data from the ESA HIPPARCOS satellite, on photometric data collected at the Swiss telescope at La Silla and on data collected with CORAVELs at the Haute Provence Observatory (France) and at ESO, La Silla Chile

© European Southern Observatory (ESO) 1998

Online publication: June 26, 1998