Astron. Astrophys. 349, 448-456 (1999)

Photometric and kinematic studies of open star clusters

I. NGC 581 (M 103)

J. Sanner ¹, M. Geffert ¹, J. Brunzendorf ² and J. Schmoll <sup>3

1</sup> Sternwarte der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany
² Thüringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg, Germany
³ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany

Received 18 March 1999 / Accepted 12 July 1999

Abstract

We present CCD photometry and a proper motion study of the young open star cluster, NGC 581 (M 103). Fitting isochrones to the colour magnitude diagram, we found an age of Myr and a distance of roughly 3 kpc for this cluster. The proper motion study identifies 77 stars of or brighter to be cluster members. We combine membership determination by proper motions and statistical field star subtraction to derive the IMF of the cluster and find a quite steep slope of .

Key words: Galaxy: open clusters and associations: individual: NGC 581 (M 103) astrometry stars: kinematics stars: Hertzsprung Russel (HR) and C-M diagrams stars: luminosity function, mass function

Send offprint requests to: Jörg Sanner (jsanner@astro.uni-bonn.de)

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Contents

• 1. Introduction
• 2. CCD photometry
• 3. Proper motion study
  • 3.1. Data reduction
  • 3.2. NGC 581
  • 3.3. Trumpler 1
• 4. Analysis of the colour magnitude diagram
  • 4.1. Field star subtraction
  • 4.2. Morphology of the cluster CMD and age determination
  • 4.3. Completeness correction
  • 4.4. Initial mass function
• 5. Summary and discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 1999

Online publication: September 2, 1999
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