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Astron. Astrophys. 357, 437-442 (2000)
Large scale star formation in galaxies *
I. The spirals NGC 7217, NGC 1058 and UGC 12732. Young star groupings in spirals
P. Battinelli 1,
R. Capuzzo-Dolcetta 2,
P.W. Hodge 3,
A. Vicari 1,2 and
T.K. Wyder 3
1 Osservatorio Astronomico di Roma, Viale del Parco Mellini 84, 00136 Roma, Italy
2 Istituto Astronomico, Università La Sapienza, Via G.M. Lancisi 29, 00161 Roma, Italy
3 Astronomy, Department, Box 351580, University of Washington, Seattle, WA 98195-1580, USA
Received 25 January 2000 / Accepted 9 March 2000
Abstract
We present multiband photometric observations of three spiral
galaxies selected in a sample suited for the study of young stellar
groupings and their relationship with the parent galaxy and the
galactic environment. Star forming regions have been identified using
an objective technique based on a multivariate statistical analysis.
Maps of young star groupings are given for each galaxy. The luminosity
functions of the young star group populations show a remarkable
similarity with a slope in the range -1.52 to -1.33. The size
distributions peak around the classical 100 pc value of the
Local Group associations for two out of the three galaxies. NGC 1058
shows smaller associations (peak at
![[FORMULA]](img1.gif)
pc). The total number of young groups
per unit B absolute luminosity of the galaxy is significantly greater
in UGC 12732. The activity of star formation is in all three galaxies
clearly stronger in the central regions.
Key words: galaxies: individual:
NGC 7217 
galaxies: individual:
NGC 1058
galaxies: individual:
UGC 12732
galaxies: stellar
content
stars:
formation
methods: statistical
* Tables 1, 2, 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html
Send offprint requests to: battinel@oarhp1.rm.astro.it; dolcetta@axrma.uniroma1.it
Contents
- 1. Introduction
- 2. Observations and data reduction
- 3. The identification techniques
- 4. Results
- 5. Discussion and conclusions
- References
© European Southern Observatory (ESO) 2000
Online publication: June 5, 2000
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