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THE CEPHEID TEMPERATURE SCALE (STARS, PULSATION)
Abstract
In this study the temperatures of Cepheid variable stars are determined by obtaining their energy distributions, using the technique of spectrum scanning. The observations were obtained with Kitt Peak National Observatory's Intensified Reticon Scanner and Cerro Tololo Inter-American Observatory's two-channel scanner. Six well-observed Cepheids in galactic open clusters were examined, at various phases of their pulsation cycles. Recently determined color excesses, based on the uvby photometry of Schmidt, were used to scale the reddening curves of Nandy and thereby correct the scans for the effects of interstellar reddening. The temperature of each energy distribution was found by matching them to the emergent flux calculated from Kurucz's model atmospheres. B-V color curves, taken from the literature, were used to establish the color index of the Cepheids at the phases for which temperatures were measured. A linear least-squares fit to these data yielded the color temperature relation: Log T(,eff) = 3.904 - 0.237 (B-V)(,0) King et al. discussed the Cepheid mass anomaly (i.e. the discrepancy between masses derived from pulsation theory and those obtained from evolutionary theory) and concluded that a temperature scale that is as cool as the one above would resolve this long-standing problem. However, the use of this temperature scale, along with Schmidt's PLC relation and color excesses, normal solar abundances, and Faulkner's formula for the pulsation constant, Q, lead to pulsation masses that are still lower than the evolutionary masses.
Subject Area
Astronomy|Astrophysics
Recommended Citation
TEAYS, TERRY JOHN, "THE CEPHEID TEMPERATURE SCALE (STARS, PULSATION)" (1986). ETD collection for University of Nebraska-Lincoln. AAI8624619.
https://digitalcommons.unl.edu/dissertations/AAI8624619