NGC 5385, NGC 2664 and Collinder 21: Three candidate open cluster remnants ^*,**

¹ Dipartimento di Astronomia, Università di Padova, Vicolo Osservatorio 2, 35122 Padova, Italy e-mail: villanova@pd.astro.it
² Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago, Chile
³ Astronomy Department, Yale University, PO Box 208101, New Haven, CT 06520-8101, USA
⁴ Suffolk University Madrid Campus, C/ Viña 3, 28003 Madrid, Spain

Received: 20 April 2004
Accepted: 26 July 2004

Abstract

We present CCD UBVI photometric and medium/high resolution spectroscopic observations obtained in the field of the previously unstudied dissolving open cluster candidates NGC 5385, NGC 2664 and Collinder 21. Our analysis is based on the discussion of star counts, photometry, radial velocity distribution, and proper motions available from the Tycho 2 catalogue. All three aggregates clearly emerge from the mean Galactic field, but, regrettably, the close scrutiny of proper motions and radial velocities reveals that we are not facing any physical group. Instead, what we are looking at are just chance alignments of a few bright unrelated stars. Our analysis casts some doubt on the Bica et al. ([CITE], A&A, 366, 827) criterion to look for Possible Open Cluster Remnants. It seems mandatory to define a better criterion to adopt for further investigations.