view Abstract Citations (5) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Dynamical Model of SU Draconis. Christy, R. F. Abstract The numerical solution of the coupled equations of motion and heat flow in the envelopes of pulsating stars (Christy, R. F., Astron. J. 68, 275, 1963) is being continued with the same technique and boundary conditions. A survey of the pulsation of RR Lyrae models, all with period of 23 day, has been made, aimed at determining the mass, radius, temperature, and composition of SU Draconis. The best fit to the observations of Oke, Giver, and Searle (Astrophys. J. 136, 393, 1962) is obtained with nearly the same parameters that they report. We find P(p/p0)~=0.035. The mass appears to lie between 0.6 and t.2 M0 and the best value for the mean radius is 4.7 x 106 km, corresponding to a mass of 0.9 M0. The hydrogen-helium ratio is closely correlated with the mean temperature and the best value is about 45 % He by mass with the mean Te = 65000. This corresponds to a minimum temperature of 60000 and gives a mean absolute bolometric magnitude of +0.1. The models in the range 30% He to 70% He are not unreasonable but require mean temperatures ranging from 62000 at 30% He to 68000 at 70% He. The quantities which appear useful in matching a computed model to the observations, in addition to the period, are the shape of the velocity curve, the magnitude of the radius variation (from the Wesselink method), the area between the luminosity curve and the mean luminosity, and the phase difference of the luminosity and velocity curves. In particular, the information from the velocity curve is important in selecting a radius and a He abundance. Correlations between the above quantities are presented. This work was supported in part by the Office of Naval Research and by the National Aeronautics and Space Administration. Publication: The Astronomical Journal Pub Date: June 1963 DOI: 10.1086/109157 Bibcode: 1963AJ.....68S.534C full text sources ADS |