Kinematic study of six galactic old open clusters

GONZÁLEZ, F.; SMITH CASTELLI, A.; CASO, J. P.; PIATTI, A.

Tandil, Provincia de Buenos Aires

Congreso; Reunión Anual de la Asociación Argentina de Astronomía Astro-2013; 2013

Instituto de Astronomía y Física del Espacio

We present Gemini GMOS spectroscopic observations of 134 stars in the field of 6 old (2-8 Gyr) open clusters in the third galactic quadrant: Be 32, Be 39, NGC 2112, NGC 2243, NGC 2682, and Tr 5. We measured radial velocities by cross-correlations and analyzed kinematic membership. Mean cluster radial velocities have been determined for 5 of the clusters. A double lined spectroscopic binary was detected in Be 32. The radial velocity distribution for Tr 5 does not allowed to identify unambiguously the cluster velocity and further observations on a larger star sample is required to complete a membership study of this cluster. For the remaining clusters our results are in agreement with published velocities, being more precise in some cases. The typical error in our mean cluster velocities is 0.5 km/s. The accuracy achieved in individual measurement of low rotating stars demonstrates the capability of GMOS for obtaining radial velocities with uncertainties of 1.5-2.0 km/s.