Observatorio Astronómico de La Plata, Paseo del Bosque s/n, 1900 La Plata, Argentina
Corresponding author: R. A. Vázquez, email@example.com
Accepted: 7 February 2001
A deep CCD UBVRI photometric survey combined with UBVRI polarimetric observations of 21 bright stars was carried out in the region of the open cluster Havlen-Moffat No. 1. Our data reveal that the extinction law in this cluster is variable and that six cluster stars show very high polarisation values (>4% ), probably because of the presence of a nearby small dust cloud. The cluster is at a distance of pc, it is 2-4 Myr old and the initial mass function of its most massive stars () has a flat slope of . As an additional result, it was possible to reconcile the absolute magnitudes of the two WN7-type members using the values valid in the regions where they are located.
Key words: cluster: open / individual: Havlen / Moffat No. 1 / stars: imaging / stars: luminosity function, mass function / ISM: dust, extinction
Based on observations collected at the University of Toronto Southern Observatory, Las Campanas, Chile, and the Complejo Astronómico El Leoncito, (CASLEO), Argentina, operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan.
© ESO, 2001