Spectroscopy of the post-AGB star HD 101584 (IRAS 11385-5517)

Abstract

From an analysis of the spectrum (4000 Ä to 8800 Ä) of HD 101584 it is found that most of the neutral and single ionized metallic lines are in emission. The forbidden emission lines of [OI] 6300 Ä and 6363 Ä and [CI] 8727 Ä are detected, which indicate the presence of a very low excitation nebula. The Hα , FeII 6383 Ä, NaI D1, D2 lines and the CaII IR triplet lines show P-Cygni profiles indicating a mass outflow. The Hα line shows many velocity components in the profile. The FeII 6383 Ä also has almost the same line profile as the Hα line indicating that they are formed in the same region. From the spectrum synthesis analysis we find the atmospheric parameters to be T_eff=8500 K, log g=1.5, V_turb=13 km s(-1) and [Fe/H] = 0.0. From an analysis of the absorption lines the photospheric abundances of some of the elements are derived. Carbon and nitrogen are found to be overabundant. From the analysis of Fe emission lines we derived T_exi=6100 K +/- 200 for the emission line region. Based on observations obtained at the European Southern Observatory (ESO), Chile and the Vainu Bappu Observatory, Kavalur, India.