A Spectroscopic and Statistical Study of Collinder 140

Extract

Spectra of 140 stars in a 1.36 square degree field centered on the open cluster Collinder , 17 outside this field, and 125 in two neighbouring fields of the same total area, have been classified on the MK system. Twenty of these were classified on slit spectra in the manner described by FitzGerald et al. (1979) and the balance on objective prism plates obtained at Cerro Tololo with a disperson of 280 A mm⁻¹. All spectra were classified at least twice, usually by more than one author. The internal accuracy was ±0.9 spectral sub-classes and ±0.4 luminosity classes. Comparison with the Michigan 10° classes of Houk (1979) for 34 stars in common gives the difference (Houk-FHM): 0.2 ± 0.2 (s. e. mean) for spectral classes and −0.1 ±0.1 for luminosity classes. All stars brighter than V=14.35-0.65 S were classified in the above regions, where S is a numerical representation of the spectral class ranging from 2.0 to 6.7 for BO to M7 stars respectively. Members are shown in Figure 1.