Astron. Astrophys. 334, 552-557 (1998)

Stellar clumps within the corona in the open cluster M 67

N.V. Chupina and S.V. Vereshchagin

Institute of Astronomy of the Russian Academy of Sciences, 48 Pyatnitskaya Str., 109017 Moscow, Russia

Received 2 June 1997 / Accepted 10 November 1997

Abstract

Several star clumps are detected inside the low-density extended corona of the open cluster M 67 with the help of the method "the distances to nearest neighbour analysis", elaborated earlier for analysis of galaxy distributions. The groups include from 5 to 11 stars and have mean sizes from 0.5 to 1.2 pc. We check the reality of their existence by statistical estimates based on kinematical data analysis. It is shown that at least one clump is not a random star density fluctuation. The question of the origin of these substructures remains open.

Key words: stars: formation open clusters and associations: individual: M 67

Send offprint requests to: S.V. Vereshchagin

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Contents

• 1. Introduction
• 2. Observational data
• 3. The method of discovering spatially bounded structures
• 4. Morphology of the corona
  • 4.1. Random density fluctuations
  • 4.2. The analysis of proper motions
  • 4.3. Clump star contents
  • 4.4. Influence of errors
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 1998

Online publication: May 15, 1998

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