Independent distance determinations to Milky Way cepheids in open clusters and associations .3. CV Mon in Anon vandenBergh
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Date
1996
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Abstract
As part of a program aimed at comparing the galactic Cepheid distance scales from cluster ZAMS fitting and from independent Baade-Wesselink techniques, we have used new, high-quality light and radial velocity curves of the Cepheid CV Mon supposed to be a member of the sparse cluster Anon van den Bergh to obtain its distance and mean radius from the visual surface brightness method, We find the distance to CV Mon to be 2160+/-200 pc which is similar to 20% larger than the ZAMS-fitting distance to the cluster determined by Turner [JRASC, 72, 248 (1978)] but cluster membership of CV Mon is still possible given the uncertainties of both determinations. Our surface brightness analysis yields a mean radius of 53.5+/-3.9 R. for CV Mon. The Cepheid's absolute visual magnitude is -3.67+/-0.36 mag, whose large uncertainty is dominated by the relatively uncertain absorption correction. Use of near infrared photometry would reduce the uncertainty in the absolute magnitude. We find rather clear evidence that CV Mon is pulsating in the fundamental radial mode. There is no evidence, neither from the existing photometry nor from radial velocity observations obtained over eleven years, that there is a binary companion to the Cepheid. (C) 1996 American Astronomical Society.