A model-atmosphere opacity code for the CN red system.

Abstract

view Abstract Citations (15) References (41) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A model-atmosphere opacity code for the CN red system. Carbon, D. F. Abstract The CN red system (A 2ll -X 2 +) is one of the most important opacity sources in a large variety of late-type stars; realistic model atmospheres for these stars must include the red-system opacity. This paper presents an opacity code for the CN red system suitable for use in model-atmosphere building. The code is based on opacity distribution functions in order to obtain an accurate and economical representation of the CN lines in the model-atmosphere calculation. The opacities are tabulated in square centimeters per gram of CN so that they can be applied in a model calculation for any chemical composition. Nearly 470,000 12CN and 13CN lines between 0.5 and 10 are included in the calculation of the code. The code explicitly includes the six internal and external satellite branches of the red system, as well as the six main branches. The laboratory and astrophysical determinations of the red-system band strengths are discussed in an effort to determine the best values for foo and Re2(r ). A classical Lorentz impact approximation is adopted for the collisional damping; the impact parameter is selected on the basis of laboratory CO broadening experiments. A random sampling technique was used to calculate the opacity distribution functions. This approach provided a substantial savings in computational time with negligible loss of accuracy. A number of examples demonstrate the behavior of the distribution functions when temperature, perturber pressure, microturbulent velocity, and 12Ci13C are varied. Subject headings: atmospheres, stellar - late-type stars - molecules - opacities Publication: The Astrophysical Journal Pub Date: August 1973 DOI: 10.1086/152277 Bibcode: 1973ApJ...183..903C full text sources ADS | data products SIMBAD (1)