Baade-Wesselink radii for NGC 1866 Cepheids
- McMaster University, Hamilton (Canada) Observatories of the Carnegie Institution of Washington, Pasadena, CA (USA) JPL, Pasadena, CA (USA)
Radial velocities and CCD photometry suitable for a Baade-Wesselink analysis are now available for six short-period Cepheids (HV12198, HV12199, HV12202, HV12203, HV12204, and V4) in the LMC cluster NGC 1866. As a prerequisite for such an analysis, O-C diagrams have been constructed and examined for seven of the NGC 1866 Cepheids (HV12197, HV12198, HV12199, HV12200, HV12202, HV12203, and HV12204), yielding improved periods and estimates of the rate of period change in these coeval variables. One star, HV12198, shows possible evidence for period change, but the phase mismatch due to that change is small enough to have negligible effect on its Baade-Wesselink radius. The computed radii are in good agreement with the Baade-Wesselink, theoretical and cluster/association period-radius relations of Fernie (1984) and the Galactic relation of Coulson and Caldwell (1989). The Flower (1977) color-effective temperature relation and the Becker et al. (1977) mass-luminosity relation lead to mean masses of 4.9 + or {minus} 0.5 solar masses and 4.6 + or {minus} 0.5 solar masses for the respective metallicities of (Y,Z) = (0.0273,0.0016) and (0.026,0.02). Pulsation constants are also computed for these stars. 66 refs.
- OSTI ID:
- 5589009
- Journal Information:
- Astronomical Journal; (United States), Journal Name: Astronomical Journal; (United States) Vol. 101; ISSN 0004-6256; ISSN ANJOA
- Country of Publication:
- United States
- Language:
- English
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71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CEPHEIDS
CHARGE-COUPLED DEVICES
GALAXIES
MAGELLANIC CLOUDS
MASS
OSCILLATIONS
PHOTOMETRY
PULSATING VARIABLE STARS
RADIAL VELOCITY
SEMICONDUCTOR DEVICES
SIZE
SPECTROPHOTOMETRY
STAR CLUSTERS
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VARIABLE STARS
VELOCITY