EDP Sciences
Free access
Volume 404, Number 3, June IV 2003
Page(s) 927 - 937
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20030524

A&A 404, 927-937 (2003)
DOI: 10.1051/0004-6361:20030524

Luminosity and Mass Function of the Galactic open cluster NGC 2422

L. Prisinzano1, G. Micela2, S. Sciortino2 and F. Favata3

1  Dipartimento di Scienze Fisiche ed Astronomiche, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
2  INAF - Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy
3  Astrophysics Division - Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands

(Received 6 May 2002 / Accepted 6 April 2003 )

We present UBVRI photometry of the open cluster NGC 2422 (age $\sim~10^8$ yr) down to a limiting magnitude $V\simeq19$. These data are used to derive the Luminosity and Mass Functions and to study the cluster spatial distribution. By considering the color-magnitude diagram data and adopting a representative cluster main sequence, we obtained a list of candidate cluster members based on a photometric criterion. Using a reference field region and an iterative procedure, a correction for contaminating field stars has been derived in order to obtain the Luminosity and the Mass Functions in the $M=0.4{-}3.5~M_\odot$ range. By fitting the spatial distribution, we infer that a non-negligible number of cluster stars lies outside our investigated region. We have estimated a correction to the Mass Function of the cluster in order to take into account the "missing" cluster stars. The Present Day Mass Function of NGC 2422 can be represented by a power-law of index $\alpha = 3.07 \pm0.08 $ (rms) - the Salpeter Mass Function in this notation has index $\alpha = 2.35$ - in the mass range $ 0.9
\leq M/M_\odot\leq 2.5 $ . The index $\alpha$ and the total mass of the cluster are very similar to those of the Pleiades.

Key words: open clusters and associations: individual: NGC 2422 -- stars: luminosity function, mass function

Offprint request: L. Prisinzano, loredana@oapa.astropa.unipa.it

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