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1. Introduction

The emission line star HD163296 (B9eV-A2eV, tex2html_wrap_inline1242) was first classified as a young Herbig Ae/Be star by Finkenzeller & Mundt (1984). Later on Thé et al. (1994) also included this object in their enlarged catalogue of Herbig stars, candidates to this group and related objects. The majority of observational properties of HD163296 is similar to those of the members of the classical catalog by Herbig (1960), although this star is not associated with nebulosity and does not demonstrate remarkable photometric variability.

The first descriptions of the line spectrum of HD163296 in the visible spectral range were given by Merrill et al. (1925), Merrill (1930) and Merrill & Burwell (1933). They noted that emission Balmer lines with narrow absorption cores and numerous low-ionization metallic shell lines were present in the spectrum. All of them are strongly variable in both intensity and position, and changes of emission and shell components take place independently.

Up to the eighties no detailed investigations of HD163296 had been carried out. The first high resolution spectroscopy of this star has shown that one of the characteristic features of the Htex2html_wrap_inline1200 variability is the transformation of the profile type from PCygII to PCygIII (according to Beals 1951), which looks as the appearance of a secondary emission peak on the blue wing of the PCyg absorption component (Finkenzeller & Mundt 1984; Thé et al. 1985). Besides HD163296, two more classical Herbig Ae stars from the catalogue of Finkenzeller & Mundt (1984) demonstrate the same type of variability (ABAur and BD+tex2html_wrap_inline1246).

The similarity of HD163296 and the young Herbig Ae/Be stars is also confirmed by results of observations in the ultraviolet (UV) and infrared (IR) spectral domains. A lot of low-ionization lines in the UV and dust IR excess have been discovered in this object (Sitko et al. 1981; Sitko 1981).

Periodicity in changes of the UV MgII resonance doublet (tex2html_wrap_inline1248h) and the CaII K line (tex2html_wrap_inline1250h) was reported by Catala et al. (1989). This phenomenon was interpreted by the authors in terms of differential rotation of the circumstellar envelope containing long-lived inhomogeneities.

A detailed investigation of the rapid line profile variability in the photospheric lines of SiII and MgII, the chromospheric CaII K and the envelope Htex2html_wrap_inline1200 lines was performed by Baade & Stahl (1989). They have found intensity changes in different parts of line profiles with no evidence of periodicity in these variations.

A detailed spectroscopic study of HD163296 in the Htex2html_wrap_inline1200 and Htex2html_wrap_inline1202 emission lines was presented by Pogodin (1994), hereafter Paper I. The main conclusions of the analysis of the line variability were as follows:

A few polarimetric measurements of HD163296 (see, for example, Gnedin et al. 1992) revealed a complicated behaviour of the multi-component polarization parameters.

All evidence mentioned above illustrates that the true understanding of the structure, kinematics and physical conditions of the circumstellar environment of HD163296 needs additional spectroscopic and polarimetric observations.

The study presented here was aimed at further investigation of circumstellar peculiarities of HD163296 with the use of:

  1. Spectroscopic data obtained at the ESO (Chile) in 1991-1992 in the region of the Htex2html_wrap_inline1200 and Htex2html_wrap_inline1202 lines. The analysis of these spectra was published in part in Paper I.
  2. New spectroscopic observations performed at LNA (Brazil) in 1992-1995 in the Htex2html_wrap_inline1200, He I 5876 and DNaI lines.
  3. tex2html_wrap_inline1264 polarimetric measurements in July, 1995 at the South African Astronomical Observatory (SAAO, South Africa).

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