IRAS 08281-4850 and IRAS 14325-6428: two A-type post-AGB stars with s-process enrichment

IRAS 08281 - 4850 and IRAS 14325 - 6428 : two A - type post - AGB stars with s - process enrichment ⋆

Aims. One of the puzzling findings in the study of the chemical evolution of (post-)AGB stars is why very similar stars (in terms of metallicity, spectral type, infrared properties, etc. . . ) show a very different photospheric composition. We aim at extending the still limited sample of s-process enriched post-AGB stars, in order to obtain a statistically large enough sample that allows us to ...

Photospheric composition of the carbon - rich 21 μ m post - AGB stars IRAS 22223 + 4327 and IRAS 04296 + 3429 ⋆

We present a detailed chemical analysis on the basis of high-resolution, high signal-to-noise optical spectra of two post-AGB objects IRAS 22223+4327 and IRAS 04296+3429. Both display the unidentified 21 μm feature in their IR-spectra. The analysis is performed using HR 1865(F0Ib) and HR 1017(F5Iab) as reference stars. The spectroscopic indicators provide accurate atmospheric parameters of Teff...

Properties of Post-agb Stars with Iras Colors Typical of Planetary Nebulae

We have investigated the infrared properties of a sample of objects with IRAS colors typical of planetary nebulae. The selected objects have not yet evolved to the planetary nebula stage since they have no detectable radio continuum emission and they are therefore likely postAGB stars.

High resolution spectroscopy of the hot post - AGB stars : IRAS 13266 - 5551 ( CPD - 55 5588 ) and IRAS 17311 - 4924 ( Hen 3 - 1428 )

The high resolution spectra covering the wavelength range 4900 Å to 8250 Å of the hot post-AGB stars IRAS13266-5551 (CPD-55 5588) and IRAS17311-4924 (Hen31428) reveal absorption lines of C II, N II, O II, Al III, Si III and Fe III and a rich emission line spectrum consisting of H I, He I, C II, N I, O I, Mg II, Al II, Si II, V I, Mn I, Fe III, [Fe II] and [Cr II]. The presence of [N II] and [O ...

IRAS Observations of Scuti Stars