A UBV study of the fields surrounding two long-period cepheids and an adjacent open cluster in Carina

Abstract

In continuation of a search for long-period [P>10d] Cepheids embedded in associations (van den Bergh et al. 1982, 1983, 1984) U, B and V plates centered on the 13.2d Cepheid GT Carinae, and including the Cepheid U Carinae and the open cluster Trumpler 17, were measured on a Cuffey Iris Astrophotometer. Colour-magnitude (CM) and colour-colour (CC) diagrams for measured stars were examined on the basis that any association of young stars to which GT car belongs would be apparent as a well defined main-sequence in the CM plane and as a distinct group of OB stars sharing analysis of the GT Car field indicates that the Cepheid is more distant than the detected OB stars associated with the Carina OB1 nebula complex. Detection of any OB stars at the distance of GT Car would require a search to a much fainter limiting magnitude than could be reached in this study.(Abstract shortened)