Atmospheric model and synthetic spectrum of LL Aquarii using Kurucz model

Abstract

Not only have interior structures, but stars also have an atmosphere. Physical processes and phenomena that occur in the atmosphere of a star also have a relationship with the stellar interior. One of them is the energy transport process produced from the stellar core and delivered to the surface and atmosphere of the star. The stellar atmospheric model is built by taking into account the changes in various parameters, such as mass depth (∫ ρ dx), temperature (T), gas pressure (Pgas ), electron density (ne ), Rosseland absorption coefficient (κR ), and radiation pressure (Prad ) to the changes in optical depth (τ) of the star. The stellar parameters used for building this model are from the LL Aquarii star which is a detached eclipsing binary star. The star system has a mass of 1.1949 M ⨀ for LL Aqr A and 1.0337 M ⨀ for LL Aqr B with effective temperatures of 6124 K and 5747 K respectively. The obtained atmospheric model is the result of bilinear interpolation of the Kurucz atmospheric grid model with Teff and g parameters. The results of the LL Aqr atmospheric model become inputs for modeling the stars synthetic spectrum using the SPECTRUM program. Convolution with the rotational velocity of the star and spectral parameters of the spectrograph instrument used will produce a synthetic spectrum that corresponds to the spectrum acquired from observations. The results showed conformity with the observed spectrum with an O-C difference of 0.05 on average.