EDP Sciences
Free access
Volume 392, Number 1, September II 2002
Page(s) 143 - 150
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020909

A&A 392, 143-150 (2002)
DOI: 10.1051/0004-6361:20020909

Discovery of spectral variation in the optical counterpart of IRAS 01005+7910

V. G. Klochkova1, 2, M. V. Yushkin1, 2, A. S. Miroshnichenko3, 4, V. E. Panchuk1, 2 and K. S. Bjorkman3

1  Special Astrophysical Observatory of the Russian Academy of Sciences, Karachai-Cirkassian Republic, Nizhnij Arkhyz 369167, Russia
2  Isaac Newton Institute of Chile, SAO Branch
3  Ritter Observatory, Dept. of Physics & Astronomy, University of Toledo, Toledo, OH 43606-3390, USA
4  Central Astronomical Observatory of the Russian Academy of Sciences at Pulkovo, 196140 Saint-Petersburg, Russia

(Received 1 March (2002) / Accepted 29 May (2002) )

We present a study of the high-resolution spectroscopic data for the proto-planetary nebula candidate IRAS 01005+7910. For the first time a careful spectral line identification is carried out, and a significant variability of the optical spectrum is detected. We found absorption lines of C II/III, N II, O II, Al III, Si III, and Mg II ( $\lambda4481$ Å), as well as emission lines of Si II and [Fe II]. Both absorption and emission components are present in the Balmer lines, Na I resonance D 1,2 lines, He I, and Fe III lines. The He I line profiles vary from straight to inverse P Cyg-type on a timescale of days to months. The resonance Na I lines show 5 absorption components at a resolution of $R=60\,000$. Additionally, the Na I D 2 line exhibits a variable emission component with a width comparable to that of the Balmer line emission components. Using the model atmospheres method within the LTE-approximation, the effective temperature ( $T_\mathrm{eff}\sim21\,500$ K), the metallicity $\mathrm{[Fe/H]}_\odot=-0.31$, and the ratio C/O>1 is reported. Finally, we suggest that IRAS 01005+7910 is a carbon-rich post-AGB star with a luminosity $\log(L/L_\odot)=3.6$ at a distance about 3 kpc.

Key words: stars: evolution -- stars: AGB and post-AGB -- stars: emission-line -- stars: individual: IRAS 01005+7910 -- techniques: spectroscopic

Offprint request: V. G. Klochkova, valenta@sao.ru

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