Pergamon www.elsevier.nl/locatelasr Adv. Space Res. Vol. 24, No. 2, pp. 177-180,1999 Q 1999 COSPAR. Published by Elsevier Science Ltd. All rights reserved printed in Great Britain 0273-1177199 $20.00 + 0.00 PII: SO273-1177(99)00498-6 SEISMIC SOLAR MODEL: BOTH OF THE RADIATIVE CORE AND THE CONVECTIVE ENVELOPE H. Shibahashi’, K. M. Hiremath1t2, M. Takata’ 1 Department of Astronomy, University of Tokyo, Tokyo 113-0033, Japan 21ndian Institute for Astrophysics, Bangalore, India ABSTRACT We determine the solar internal structure by solving the basic stellar structure equations with the imposition of the sound speed, which is inferred from helioseismology. As for the radiative core, all the four structure equations are solved with the boundary conditions set at the center and at the top of the radiative core. As for the convective envelope, we only have to solve the basic equations for mass conservation and hydrostatic equilibrium with the imposition of the sound-speed profile determined from helioseismology, as an intial value problem from the base of the convection zone. The helium abundance is obtained as a part of the solutions. The extent of the convection zone is also determined so that the temperature gradient matches the adiabatic gradient at the bottom of the zone, and the deduced depth is 0.718Ra. Q 1999 COSPAR. Published by Elsevier Science Ltd. INTRODUCTION Until the advent of helioseismology, the solar structure has been understood from the evolutionary models. A one-solar-mass stellar model is evolved up to the present age of the sun by adjusting the initial helium abundance and the efficiency of convective energy transport so that the model satisfies the observed radius and luminosity of the present sun. Helioseismology opened another way of determining the structure of the present sun; the solar structure is determined as the solution of stellar structure equations by imposing the helioseismologically inferred sound speed (Shibahashi 1993, Shibahashi and Takata 1996, 1997; Takata and Shibahashi 1998a, b). The latter method has two advantages over the solar evolutionary models; no assumption of the history of the sun and no need to compute the convective flux. Takata and Shibahashi (1998b, hereafter we refer it as TS98) have developed a seismic model for the region from the center to the base of the convection zone. In this paper, we extend the region of the interest to the whole part of the solar interior in order to get a consistent global seismic model, whose preliminary results are presented at the IAU symposium No. 185 (Shibahashi, Hiremath, and Takata 1998). METHODOLOGY OF MAKING A SEISMIC SOLAR MODEL We assume that the sun is in hydrostatic equilibrium and in thermal balance. We ignore the effects of rotation and magnetic fields and treat the sun as a spherically symmetric star. Then the basic equations governing the internal structure of the sun are the same as those used in the theory of stellar structure. In 177