Title

Abundance Analysis of the New Carbon-Rich Proto-Planetary Nebula IRAS 06530-0213

Document Type

Article

Publication Date

6-2003

Abstract

In this paper we present a study of the proto - planetary nebula (PPN) IRAS 06530 - 0213 based on low- and high-resolution spectra. The low- resolution spectrum shows that the star is an F5 supergiant with molecular C-2 and C-3 and enhanced s-process lines. From the high-resolution spectra, the following atmospheric parameters were determined: T-eff = 6900 K, log g = 1.0, and xi(t) = 4.5. Abundance analysis shows that IRAS 06530-0213 is metal-poor ([Fe/H] = -0.9) and overabundant in carbon ([C/Fe] = 1.3), nitrogen ([N/Fe] = 1.0), and s-process elements ([s-process/Fe] = 1.9), indicating asymptotic giant branch (AGB) nucleosynthesis and deep convective mixing. From the analysis of circumstellar C-2 and CN molecular bands in the spectrum of IRAS 06530 - 0213, an envelope expansion velocity of V-exp = 14 +/- 1 km s(-1) was determined, a typical value for post-AGB stars. Also typical of PPNs is the double-peaked spectral energy distribution. The properties of both the photosphere and circumstellar envelope suggest that IRAS 06530 - 0213 is unambiguously a low-mass, carbon-rich PPN. For comparison purposes, new, high-resolution spectra of the well-known PPN HD 56126 ( IRAS 07134+1005) were also analyzed and compared with previous results.