Luminosity and mass function of galactic open clusters I. NGC 4815

Free access article

Issue		A&A Volume 369, Number 3, April III 2001


Page(s)		851 - 861
Section		Stellar clusters and associations
DOI		http://dx.doi.org/10.1051/0004-6361:20010202

A&A 369, 851-861 (2001)
DOI: 10.1051/0004-6361:20010202

Luminosity and mass function of galactic open clusters I. NGC 4815

L. Prisinzano^{1, 2}, G. Carraro², G. Piotto², A. F. Seleznev³, P. B. Stetson⁴ and I. Saviane⁵

¹ Osservatorio Astronomico di Palermo, Piazza del Parlamento 1, 90134, Palermo, Italy
² Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 5, 35122 Padova, Italy
³ Astronomical Observatory, Ural State University, pr. Lenina 51, Ekaterinburg, 620083 Russia
⁴ Dominion Astrophisical Observatory, Herzberg Institute of Astrophysics, National Res earch Council of Canada, 5071 West Saanich Road, Victoria, British Columbia V8X 4M6, Canada
⁵ UCLA/ Department of Physics and Astronomy, Los Angeles, CA 90095-1562, USA

(Received 30 June 2000 / Accepted 23 January 2001 )

Abstract
We present deep V and I photometry for the open cluster NGC 4815 and four surrounding Galactic fields down to a limiting magnitude $V\sim25$ . These data are used to study cluster spatial extension by means of star counts, and to derive the luminosity (LF) and mass function (MF). The radius turns out to be $3.6\pm0.3$ arcmin at V=19.0, whereas the mass is $880\pm230 m_{\odot}$ down to V=20.8. From the color-magnitude diagram, we obtain the LFs in the V and I bands, using both the standard histogram and an adaptive kernel. After correction for incompleteness and field star contamination, the LFs were transformed into the present day mass functions (PDMF). The PDMFs from the V and I photometry can be represented as a power-law with a slope $\alpha = 3.1\pm0.3$ and $\alpha = 2.9\pm0.3$ (the (Salpeter 1955) MF in this notation has a slope $\alpha = 2.35$ ) respectively, in the mass range $2.5 \leq \frac{m}{m_{\odot}} \leq 0.8$ . Below this mass, the MF cannot be considered as representative of the cluster IMF, as it is the result of the combined effect of strong irregularities in the stellar background, probable internal dynamical evolution of the cluster and/or interaction of the cluster with the dense Galactic field. Unresolved binaries and mass segregation can only flatten the apparent derived IMF, so we expect that the real IMF must be steeper than the quoted slope by an unknown amount.

Key words: open clusters and associations; individual: NGC 4815 -- methods: statistical

Offprint request: G. Carraro, carraro@pd.astro.it

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.