High-Luminosity, Fully Convective Contracting Sun.

Abstract

view Abstract Citations (1) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Luminosity, Fully Convective Contracting Sun. Ezer, I. D. ; Cameron, A. G. W. Abstract Last year Hayashi predicted that the sun would be fully convective in its early contracting phases and would have a high luminosity. This follows from the consideration that the photosphere must occur at about an optical depth of unity, which requires that the photospheric density and temperature must both be high in order to provide the necessary opacity. High temperature means high luminosity in the red-giant stage of contraction; high density and high luminosity both require deep outer convection zones. New models of the contracting sun have been constructed in which particular care has been taken to treat the outer convection zone and transition layer to the photosphere realistically. Opacities were calculated from the Los Alamos code and crude line corrections were added. For purposes of general exploration the models were not calculated in strict evolutionary sequences, but rather subject to the restriction that dr/rdt is constant throughout the model. We find that Hayashi's predictions are fully correct. For all models with R/R ~3, convection is complete to the center. It is possible to construct models out to several hundred solar radii (but see accompanying Cameron-Ezer paper, p. 572); their surface temperatures lie in the range 26000M6000K. One can roughly say that these models descend nearly vertically in the color-magnitude diagram. The luminosity reaches a minimum near R/R = 1.7 and then increases slightly as further contraction proceeds towards the main sequence. Publication: The Astronomical Journal Pub Date: November 1962 DOI: 10.1086/108770 Bibcode: 1962AJ.....67..575E full text sources ADS |