Spectroscopy of Post-AGB Candidate HD 331319 (IRAS 19475+3119)

Abstract

HD 331319 is a F3 Ib star with a detached cold circumstellar dust shell with far-IR colours similar to planetary nebulae. From an analysis of high resolution spectra using LTE stellar atmospheric models, we have derived the atmospheric parameters and the chemical composition of HD 331319. By matching the theoretical and the observed spectrum we obtained T-eff=7500K, log g=0.5 and xi(t)=7 kms(-1) and estimated {[}C/Fe] = 0.4 +/- 0.3, {[}N/Fe] =1.4 +/- 0.5, {[}O/H]=0.3 +/- 0.3, {[}Fe/H] = -0.2 +/- 0.3 We find that nitrogen is overabundant, oxygen and iron are nearly solar. The total C,N,O abundances with respect to iron indicate mixing due to the third dredge-up.