EDP Sciences
Free access
Volume 431, Number 3, March I 2005
Page(s) 1007 - 1017
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20041506

A&A 431, 1007-1017 (2005)
DOI: 10.1051/0004-6361:20041506

High resolution spectroscopy of the hot post-AGB stars IRAS 13266-5551 (CPD-55 5588) and IRAS 17311-4924 (Hen3-1428)

G. Sarkar1, M. Parthasarathy2 and B. E. Reddy2

1  Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007, India
    e-mail: gsarkar@iitk.ac.in
2  Indian Institute of Astrophysics, Koramangala, Bangalore 560034, India

(Received 22 June 2004 / Accepted 23 September 2004 )

High resolution spectra covering the wavelength range 4900 Å to 8250 Å of the hot post-AGB stars IRAS 13266-5551 (CPD-55 5588) and IRAS 17311-4924 (Hen3-1428) 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 I] lines and absence of [O III] indicate low excitation nebulae around these stars. The components of Na I absorption lines indicate the presence of neutral circumstellar envelopes in addition to the low excitation nebulae around these two hot post-AGB stars. The H $_\alpha$ lines show P-Cygni profiles indicating ongoing post-AGB mass loss. From the absorption lines we derived heliocentric radial velocities of 65.31  $\pm$ 0.34 km s -1 and 27.55  $\pm$ 0.74 km s -1 for IRAS 13266-5551 and IRAS 17311-4924 respectively. The high Galactic latitude and large radial velocity of IRAS 13266-5551 indicate that it belongs to the old disk population. Preliminary estimates for the CNO abundances in IRAS 13266-5551 are obtained.

Key words: stars: AGB and post-AGB -- stars: early-type -- stars: abundances -- stars: evolution

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© ESO 2005