The Calculation of Flux Constant Line-Blanketed Model Atmospheres for Solar Type Stars

Two computer programs have been used to compute flux constant model atmospheres, which include the effects of convection as well as line blanketing, for solar type stars. One program computes a model atmosphere and then calculates the integrated radiative flux and convective flux as a function of optical depth. After applying a line-blanketing correction to the fluxes, temperature corrections are calculated and a new model atmosphere computed. A second program computes the line blocking of a model atmosphere as a function of optical depth. The line-blocking data, expressed as a function of the radiative flux computed without allowance for line absorption, is used by the model atmosphere program to allow for line absorption effects. This method of computing line-blanketed model atmospheres, the flux-fraction method, does not make the opacity correlation assumption that is inherent in the giant-line method. Model atmospheres have been computed for the Sun, a metal deficient star $$([A/H] = -0.6)$$ and Groombridge 1830 and the colours of these models are discussed. The models do predict the observed variation of ultra-violet excess, $$\delta(U-B)$$ , with metal abundance.