IUE high-resolution observations of Mira B.

Abstract

A high-resolution spectrum of Mira obtained with IUE on 1983 July 7 confirms the presence of broad emission lines with typical half base widths of ≅300 to roughly 1000 km s^-1. No narrow emission lines are detected. The observed broad lines cannot originate from the extended atmosphere of the cool giant variable. The authors show in particular that the intercombination lines of Si III] and C III] are consistent with formation in a rapidly rotating disc around the white-dwarf companion Mira B with typical radius of ≅10¹¹cm, thickness ≅10¹⁰cm, and electron density N_e ≅ 1.1×10¹⁰cm^-3.