EDP Sciences Journals List
Advanced Search
Subscriber Authentication Point
Home All issues Volume 494/1 Article
Free access article

Issue A&A
Volume 494, Number 1, January IV 2009
Page(s) 81 - 93
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:200811068
Published online 11 December 2008

A&A 494, 81-93 (2009)
DOI: 10.1051/0004-6361:200811068

The spatial distribution of star and cluster formation in M 51

R. A. Scheepmaker, H. J. G. L. M. Lamers, P. Anders, and S. S. Larsen

Astronomical Institute, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
    e-mail: R.A.Scheepmaker@uu.nl

Received 1 October 2008 / Accepted 2 December 2008

Abstract
Aims. We study the connection between spatially resolved star formation and young star clusters across the disc of M 51.
Methods. We combine star cluster data based on B, V, and I-band Hubble Space Telescope ACS imaging, together with new WFPC2 U-band photometry to derive ages, masses, and extinctions of 1580 resolved star clusters using SSP models. This data is combined with data on the spatially resolved star formation rates and gas surface densities, as well as H$\alpha$ and 20 cm radio-continuum (RC) emission, which allows us to study the spatial correlations between star formation and star clusters. Two-point autocorrelation functions are used to study the clustering of star clusters as a function of spatial scale and age.
Results. We find that the clustering of star clusters among themselves decreases both with spatial scale and age, consistent with hierarchical star formation. The slopes of the autocorrelation functions are consistent with projected fractal dimensions in the range of 1.2-1.6, which is similar to other galaxies, therefore suggesting that the fractal dimension of hierarchical star formation is universal. Both star and cluster formation peak at a galactocentric radius of ~2.5 and ~5 kpc, which we tentatively attribute to the presence of the 4:1 resonance and the co-rotation radius. The positions of the youngest (<10 Myr) star clusters show the strongest correlation with the spiral arms, H$\alpha$, and the RC emission, and these correlations decrease with age. The azimuthal distribution of clusters in terms of kinematic age away from the spiral arms indicates that the majority of the clusters formed ~5-20 Myr before their parental gas cloud reached the centre of the spiral arm.


Key words: galaxies: individual: M 51 -- galaxies: star clusters



© ESO 2009


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.