Carbon and Nitrogen Lines in the Spectra of Wolf-Rayet Stars

Abstract

Predictions of 29 energy ratios involving emission lines of He II, C II, C III, C IV, N III, N IV, and N V are presented. Comparison of observed energy ratios with the predicted energy ratios shows that WC spectra can be understood in terms of solar composition, T_* = 2.5 × 10⁴K, 5×10⁴ ≤ T_e ≤ 10⁵K, and N_e ≈ 10¹⁰cm^-3, while WN spectra imply solar composition, T_* = 2.5×10⁴K, 10⁵ ≤ T_e ≤ 2×10⁵K, 10⁹ ≤ N_e ≤10¹⁰cm^-3. The line-emitting regions have volumes of the order of 10⁴¹ - 10⁴⁴cm³. The line-emitting regions may be in the form of thin disks having radii of the order of 10¹⁵cm. It is noted that Population I Wolf-Rayet stars may be young objects still surrounded by remnant natal disks, while Population II Wolf-Rayet stars may be surrounded by disks generated by their red giant parents.