Bump masses for BL HER stars
Abstract
The masses of classical Cephieds are determined by using the phase of the Hertzsprung bump on the light or velocity curve, CoxStewart opacities, and nonlinear pulsation theory. The light curve for BL Her, a population II Cepheid, is calculated with an observed bump on the declining portion of its light curve. The nonlinear hydrodynamic model used resolves the light curve by dynamic zoning nd allows the opportunity to make a direct comparison of the calculated light curve to the observations, using a prescribed mass, luminosity, and effective temperature. The parameters for BL Her are from a linear model that has nearly the correct period and the correct period ratio from resonance theory for a bump to appear on the declining portion of the light curve as observed. These parameters are: M = 0.55 M, L = 95.0 L, and T_{eff.} = 6500 K. The model results agree well with the observations and the colorT_{eff} relation has the same slope as that observed for RR Lyrae stars.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 1982
 Bibcode:
 1982STIN...8327943D
 Keywords:

 Cepheid Variables;
 Light Curve;
 Luminous Intensity;
 Mass To Light Ratios;
 Stellar Mass;
 Stellar Temperature;
 Hydrodynamics;
 Mathematical Models;
 Nonlinearity;
 Astronomy