Observations and spectra reduction

We have obtained spectra of IRAS04296 with the CCD (1140$\times$1170 pixels) equipped echelle spectrometer PFES mounted at the prime focus of the 6m telescope of SAO RAS (Panchuk et al. 1998). The echelle-grating with ${\rm 75\,gr/mm}$ and with a blaze angle of ${\rm \Theta\,=\,64.3\,^{o}}$ was used. A diffracton grating with ${\rm 300\,gr/mm}$ was used as the cross-disperser. The camera has f=140mm. The size of input slit is 0.54arc sec.

We observed IRAS04296 on October 07, 1996 (JD2450363.6) and February 26, 1997 (JD2450506.3). The echelle frames with 25 echelle-orders cover the spectral region ${\rm \lambda\lambda}$4420-8300Å. The average spectral resolution was 0.4Å. The signal-to-noise ratio was in the range 50-110 for different spectral orders.

All usual procedures needed for echelle-images reduction (bias subtraction, cosmic ray removal, optimal order extraction, rebinning) were made using the ECHELLE context of the MIDAS system. A Gaussian function approximation was made for the measurement of equivalent widths. The comparison spectrum source was an argon-filled thorium hollow-cathode lamp.

The distinctive features of the optical spectrum of the source IRAS04296 are a peculiar profile of the ${\rm H_{\alpha}}$ line (see Fig.1), molecular emission bands and very strong absorption lines of ionized atoms of s-process elements (Y, Zr, Ba, La, Ce, Pr, Nd). For example, the equivalent widths of BaII lines (6141 and 6496Å) exceed 0.6Å.

  

Figure: The IRAS04296+3429 spectrum near ${\rm H_{\alpha}}$.