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

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 ( 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 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 . Additionally, the Na i D2 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 ( K), the metallicity , and the ratio is reported. Finally, we suggest that IRAS 01005+7910 is a carbon-rich post-AGB star with a luminosity at a distance about 3 kpc.