An optical and near IR study of the old open cluster NGC 2141^*

¹ Dipartimento di Astronomia, Universitá di Padova, vicolo dell'Osservatorio 5, 35122 Padova, Italy
² National Research Institute of Astronomy and Geophysics, Helwan, Cairo, A.R.E.
³ Osservatorio Astronomico di Padova, vicolo Osservatorio 5, 35122, Padova, Italy e-mail: carraro,ortolani,vallenari@pd.astro.it

Corresponding author: G. Carraro, carraro@pd.astro.it

Received: 8 February 2001
Accepted: 9 April 2001

Abstract

We report CCD optical (B and V passbands) and near IR (J and K bands) observations in the region of the old open cluster NGC 2141. By combining the two sets of photometry (500 stars in common) we derive new estimates of the cluster's fundamental parameters. We confirm that the cluster is 2.5 Gyrs old, but, with respect to previous investigations, we obtain a slightly larger reddening (), and a slightly shorter distance (3.8 kpc) from the Sun. Finally, we present the Luminosity Function (LF) in the V band, which is another age indicator. We provide a good fit for the age range inferred from isochrones by assuming the Kroupa et al. ([CITE]) IMF up to M_V = 5.0. We interpret the disagreement at fainter magnitudes as evidence of mass segregation.