Abstract:
We have done a detailed abundance analysis of four unexplored cand
idate post-
Asymptotic Giant Branch(AGB) stars IRAS 13110- 6629, IRAS 175
79 - 3121, IRAS
18321- 1401 and IRAS 18489- 0629 using high resolution spectra. W
e have constructed
Spectral Energy Distributions (SED) for these objects using the
existing photometric
data combined with infrared (IR) fluxes. For all sample stars, the S
EDs exhibit double
peaked energy distribution with well separated IR peaks showing th
e presence of dusty
circumstellar material. The CNO abundances indicate the production
of N via CN
cycling, but observed [C/Fe] indicates the mixing of carbon produce
d by He burning
by third dredge up although C/O ratio remains less that 1. A moderat
e DG effect is
clearly seen for IRAS 18489 - 0629 and IRAS 17579- 3121 while a large
scatter observed
in depletion plots for IRAS 18321- 1401 and IRAS 13110 - 6629 indicat
e the presence
of other processes affecting the observed abundance pattern.
