Luminosity and mass functions of galactic open clusters

II. NGC 4852

¹ Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
² Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile e-mail: gcarraro@das.uchile.cl
³ Astronomy Department, Yale University, PO Box 208101, New Haven, CT 06520-8101, USA
⁴ Facultad de Ciencias Astronómicas y Geofísicas de la UNLP, IALP-CONICET, Paseo del Bosque s/n, La Plata, Argentina
⁵ ESO-Chile, Casilla 19001, Santiago, Chile

Received: 23 April 2004
Accepted: 8 February 2005

Abstract

We present wide-field deep photometry for the previously unstudied open cluster NGC 4852 down to a limiting magnitude , obtained from observations taken with the Wide Field Imager camera on-board the MPG/ESO 2.2 m telescope at La Silla (ESO, Chile). These data are used to obtain the first estimate of the cluster basic parameters, to study the cluster spatial extension by means of star counts, and to derive the Luminosity (LF) and Mass Function (MF). The cluster radius turns out to be  arcmin. The cluster emerges clearly from the field down to  mag. At fainter magnitudes, it is completely confused with the general Galactic disk field. The stars inside this region define a young open cluster (200 million years old) 1.1 kpc far from the Sun (, ). The Present Day Mass Functions (PDMF) from the V photometry is one of the most extended in mass obtained to date, and can be represented as a power-law with a slope and (the Salpeter MF in this notation has a slope ), in the mass range . Below this mass, the MF cannot be considered as representative of the cluster MF, as the cluster merges with the field and therefore the MF is the result of the combined effect of strong irregularities in the stellar background and interaction of the cluster with the dense Galactic field. The cluster total mass at the limiting magnitude results to be .