Publications

CRDF grant RP1-2264

Main scientific results

The first period

During the 1-st period high resolution CCD-spectra of the fast evolving hypergiant IRC+10420, obtained in 1997-2000 with the 6-meter telescope, were processed. Radial velocities of numerous emission and absorption lines, including HI profiles, were measured. The spectral type, effective temperature and luminosity were estimated using spectroscopic criteria only. Now we analyze the results obtained for this peculiar object.
New high resolution spectra of the fast evolving star FG Sge were obtained with the echelle spectrometer PFES at the 6-m telescope. Fundamental parameters and detailed chemical composition were determined using the model atmosphere metod. We have been monitoring this fast evolving object spectroscopically since 1994: a sample of the FG Sge spectra is posted on-line.
New spectra of the LBV-object HD168625 B6Ia+, two LBV-candidates, HD168607 (B9Ia+) and AS314 (A0Ia), and two peculiar Be-stars MWC1080 and AS381 were processed. They were obtained with high resolution CCD-echelle spectrometers LINX and PFES at 6-m telescope. Relative intensities, radial velocities for some hundred of lines were measured and typical profile shapes were obtained. A spectral atlas for HD168625, HD168607, AS314 and the normal supergiant HD183143 B7Ia was prepared for publication.
The main purpose of the investigation of the first three objects are a clarification of the models of their winds and an attempt to get the additional spectroscopic differences between the true hypergiants and theirs simulations by the low-mass stars. The clarification of the nature and the evolutinary state is the task of the investigation of the two last objects.
The observing mode of the echelle-spectrometer LYNX in combination with the circular polarization analyzer was developed and tested at the Nasmyth focus of the 6-meter telescope. The modernization of the existing spectrometer PFES inside the prime focus cage of the 6-meter telescope has started, aiming at measurements of linear polarization in high-resolution spectra. The complete set of optical components for this observing mode are now available.
Current results of a study of sample of stars evolved from AGB to the planetary nebulae stage were presented as a short review: Klochkova V.G., Panchuk V.E., Szczerba R. "Optical spectroscopy of selected PPN candidates", which will be published in Astrophysics and Space Science, 2001.

The second period

Based on CCD-spectra obtained with echelle-spectrometers at the 6-m telescope, we have determined fundamental parameters and detailed chemical composition of the far evolved object associated with the OH/IR-star IRAS18123+0511. Metallicity and chemical composition of the optical counterpart of the OH/IR-star IRAS18123+0511 were determined for the first time. The overall pattern of chemical abundances confirms the AGB evolutionary stage for the object IRAS18123+0511. The metallicity, in combination with the radial velocity Vr=+78.0 km/sec and a high galactic latitude, indicates that the object likely belongs to the old disk population. The expansion velocity of the circumstellar envelope V_exp=21 km/sec is estimated from positions of absorbtion features, which are formed in the envelope.
These results are presented in the paper: Klochkova V.G., Panchuk V.E., Tavolganskaya N.S. "Optical spectra of 3 stars at the asymptotic branch stars", which will be published in a Russian journal "Astronomy Reports", 2001.
During the reporting period we analyzed spectroscopic data for the fast evolving supergiant IRC+10420. These data were obtained in 1997-2000 with the echelle spectrometer of the 6-m telescope and processed in the previous quarter. The radial velocity (with respect to the local standard of rest) of IRC+10420 has been found to be 93 km/s from pure absorption lines without visible emmision components (HeI, OI, NI, SiII) and from absorption components of the Balmer hydrogen lines. Both emission and absorption lines show correlations between radial velocities and oscillator strengths. A variability of the relative intensity of the Halpha and Hbeta emission components has been revealed. The spectral type A2 was estimated from the IRC+10420 spectrum obtained in 2000, and this corresponds to an effective temperature of 9200K. We have concluded that IRC+10420 is evolving rapidly to the Wolf-Rayet stage, and that the current rate of temperature increase is 120K per year. The luminosity based on the OI, 7773A triplet strength is equal to Mbol=-9.5 mag. All optical spectra of IRC+10420 show a helium absorption line HeI 5876 A with a significant equivalent width of no less 200mA, at such a low effective temperature it could be caused by both the very high luminosity and the helium abundance excess in the atmosphere of the supergiant.
The results are presented in the paper: Klochkova V.G., Yushkin M.V., Chentsov E.L., Panchuk V.E. "Evolution alternations in optical spectra of peculiar supergiant IRC+10420", which was submitted by a Russian journal "Astronomy Reports" in March 2001.
The detailed spectral atlas of pre-planetary objects and B-A supergiants is close to completion. The atlas includes V1853 Cyg, IRAS18062+2410, MWC162 and the central star of the planetary nebula NGC6543. The spectral range is 4300-7800 AA, the spectral resolution limit is 0.5 A. The interesting variations of the radial velocity and the line profiles in the spectrum of AS314 are revealed and investigated. They are especially appreciable between the seasons of 1998 and 2000 and could point to the nonsphericity of the wind or to the spectral duplicity.
New techniques for carrying out observations with the echelle-spectrometer LYNX at the Nasmyth focus of the 6-meter telescope, using the circular polarization analyzer in combination with a half-wave plate, were prepared and tested. The half-wave plate provides a phase shift "lambda/2". Inserting a half-wave plate before an analyzer, we change locations of echelle orders with left and right circular polarization. This permits us to minimize methodic errors caused by the locations of echelle orders with left and right polarization at different places on the CCD. The design of such an adapter allows us to input either a half-wave or a quarter-wave plate. Additionally, we can rotate the quarter-wave plate. That permits us, in principle, to use the echelle-spectrometer LYNX to measure all 4 Stokes parameters (the possibility of such an extended usage of the spectrometer LYNX will be better understood after investigation of instrumental polarization in the Nasmyth focus of the 6m telescope).
The observing mode is described in a paper: Panchuk V.E., Klochkova V.G., Najdenov I.D., Romanenko V.P., Yushkin M.V. "Spectroscopic complex of the Nasmyth focus of the 6m telescope. Fast echelle-spectropolarimeter." Preprint of the Special Astrophysical Observatory. 2001.
The reconstruction of the echelle-spectrometer PFES in the prime focus of the 6m telescope was completed, aiming at measurements of linear polarization. As a result, we now have the possibility to provide different position angles of the spectrometer inside the prime focus cage. A linear polarization analyser for the spectrometer PFES has been made. The analyser consists of two CaCO3 crystals oriented at an angle of 90 degrees with respect to each other. The design of the analyser enables the same optical path for ordinary and extraordinary beams and provides the same intensity for both polarized beams after the diffraction gratings of the spectrometer. An additional cross-disperser grating was bought to increase the separation between echelle orders.
This new observing mode is described in a paper: Panchuk V.E., Klochkova V.G., Yushkin M.V., Romanenko V.P., Najdenov I.D., Ermakov S.V. "Echelle-spectropolarimeter for the prime focus of the 6m telescope." Preprint of the Special Astrophysical Observatory. 2001.
Methods to extract echelle spectra obtained with a linear or circular polarization analyzer have been developed. The Stokes parameter determination procedure has been developed. The procedure takes into account a wavelength shift between spectral order components. This package has been developed inside the MIDAS software environment (version 01FEB) using the standard procedures in the "Echelle" and "Spec" contexts.
In January 2001 we performed the first observations to measure linear polarization in a high spectral resolution mode at the 6m telescope. The echelle spectrometer PFES inside the prime focus cage of the 6m telescope, in combination with a spectropolarimetric analyzer, was used for registration of linear polarization in the spectra of several spectropolarimetric standards and some program stars. We obtained spectropolarimetric data in a spectral range 4950-6620 A with spectral resolution R=15000 for 21 program stars. To illustrate the observations, we present echelle frames for the peculiar supergiant R CrB and for the famous bipolar nebula AFGL2688 (Egg Nebula).
The first results and the initial experience gained in spectropolarimetry in a high spectral resolution mode allow us to begin the project of a specialized spectropolarimeter for the prime focus aiming for measurements of the 4 Stokes parameters.

The third period

From CCD-spectra obtained with the echelle-spectrometer of the 6-m telescope, the fundamental parameters and detailed chemical composition of the star HD 331319 are determined. This star is the optical counterpart of the IR-source IRAS19475+3119. In the spectrum of this high luminosity object (Mv < -8) with an effective temperature of Te ~ 7250 K, helium lines were found to indicate a significant helium excess in the outer atmospheric layers. This may be evidence of possible helium synthesis during the course of previous evolution. The nitrogen and oxygen overabundances were found to be [N/Fe]_sun=+1.30 dex and [O/Fe]_sun=+0.64 dex, even though the star shows a very small carbon excess. The metallicity [Fe/H]_sun = -0.25 for the stellar atmosphere is not significantly distinquished from the solar value. The determined abundance of s-process metals Y, Zr [X/Fe]_sun = -0.68 is not overabundant; rather, it is somewhat underabundant relative to the metallicity. We also find [Ba/Fe]_sun = -0.47. Other heavy elements such as La, Ce, Nd, Eu are slightly enhanced relative to iron: their averaged abundance [X/Fe]_sun = +0.16. In sum, the chemical abundances pattern confirms the post-AGB evolutionary stage for the object IRAS 19475+3119. The ratio O/C > 1 derived for the atmosphere of the central star agrees with details observed in the radio region. The object's metallicity, in combination both with the radial velocity value RV = -3.4 km/sec and with the galactic latitude |b| = 2.7 degrees, suggests that it is located in the galactic disk. The expansion velocity of the circumstellar envelope, V_exp, is found to be approximately 21 km/sec measured from the wavelengths of absorption lines formed in the envelope. In addition to the results for HD 331319, interesting results were also found for a standard star. Comparing the results obtained in this study for the standard star (a typical post-AGB star), HD161796 = IRAS 17436+5003, with data published earlier, we found evidence for an evolutionary change of its effective temperature with a rate of at least 50K per year. (Klochkova V.G., Panchuk V.E., Tavolganskaya N.S.)
Two new spectra of the post-AGB star IRAS22223+4327 have been analyzed. The spectra have been obtained with the echelle spectrometer NES (R=30000) and echelle spectrometer PFES (R=15000) of the 6-m telescope BTA. The high resolution spectrum was used for the determination of atmospheric parameters and for calculations of chemical composition using a model atmosphere comparison. The model atmosphere used had parameters of Teff=6500K, log(g)=1.0, V_t=5.0 km/s; these are in good agreement with atmospheric parameters published for the star. The metallicity and details of chemical composition of the star indicates a value of [Fe/H]=-0.3. In the high resolution spectrum we have resolved four absorbtion components of the NaI D1,D2 lines. One of them is likely to be associated with the interstellar medium, one with the stellar atmosphere, and the two strongest components are associated with the circumstellar envelope. In the PFES spectrum we have detected C_2 bands of the Swan system; (0,0) and (1,1) are found to be in absorption, while (0,1) and (1,2) are in emission. In addition, we have detected CN bands of the Red system (2,0),(3,0) and (4,0). (Klochkova V.G., Panchuk V.E., Yushkin M.V.)
The work on the spectral atlas of hypergiants is completed. It includes: graphs of spectra of HD168625 (B6Ia+), HD183143 (B7Ia), HD168607 (B9Ia+), and AS314 (A0Ia) between 4700 and 6700 angstroms; tables of the identified lines and averaged radial velocities for the groups of lines; and typical line profiles and their variability with a time. The spectrum from the last season for hypergiant AS314 revealed interesting time variations of the profile shapes. (Chentsov E.L., Ermakov S.V., Klochkova V.G., Panchuk V.E., Bjorkman K.S., Miroshnichenko A.S.)
Aiming for linear polarization measurements, the design of the spectropolarimeter for Cassegrain focus of the 1-m telescope of the Special Astrophysical Observatory is completed. The device, which has two changeable diffraction gratings (1200 and 600 grooves/mm), provides a spectral resolution of R=1100 and R=2300, respectively, at 2.5 pixel projection of the entrance slit. A fixed symmetric analyzer is installed behind the slit. The layout of the spectrometer and the design of the CCD's cryostat allow changes to the position angle of the spectropolarimeter. The diameter of the collimator (F/6.5), the size of the ruled area of the gratings, and the size of the input pupil of the camera allows us to use all starlight up to seeing values of 3.5 arc sec. A changeable input aperture also allows usage of the device as a spectrophotometer. At present, the spectropolarimeter is undergoing testing in the laboratory. (Panchuk V.E.)
Some different techniques for measurement of all 4 Stokes parameters at the Nasmyth focus of the 6m telescope are have been analyzed. The technical design for manufacturing of the unit to provide the counter-rotation of the polarimetric vector at the entrance of the spectropolarimeter has been prepared. (Panchuk V.E., Najdenov I.D.)
In addition, an analysis of various possible layouts for a high resolution spectropolarimeter for the prime focus of the 6-m telescope was performed. (Panchuk V.E.).

The fourth period

At the beginning of this period the visit by the U.S. team to the SAO 6-meter observatory was completed. It was a very successful visit, enabling the teams to carry out detailed discussions of science goals and instrument development. It also allowed the U.S. team to become more familiar with the capabilities and observation modes of the 6-meter telescope and instrumentation. At present, plans for the reciprocal visit of the FSU team to the U.S are made, and the application process for visas is underway. The visit is expected to occur during November 2001. Communication between the U.S. and FSU teams continues via e-mail at this time.
During the reporting period 2 successful observing runs were completed at the 6-meter telescope. In July (02-07) we obtained numerous spectra of LBV and faint protoplanetary candidates with the prime focus echelle spectrometer PFES (resolving power R=15000). In August (09-10) we obtained several high-resolution spectra (R=25000) of our program objects: MWC297, MWC342, MWC623, VXCas, IRAS01005+7910 with the echelle spectrometer LYNX.
The algorithms for spectropolarimetric echelle frame reduction were improved. These algorithms were tested using spectra of polarimetric standards. To illustrate this we present 3 figures (the postscript figures are appended in a separate e-mail message). In Figure 1 a fragment of the polarization spectrum of a standard star HD204827, in a region containing the HeI 5876 A photospheric line and the NaI 5890 and 5986 A interstellar lines, is shown. The polarization level for both the continuum and the photospheric line spectrum is in agreement with the broadband polarimetry of the star, which has a polarization in the V-band (centered at 5500 A) Pv=5.4%. However, the interstellar sodium doublet has a different degree and position angle of polarization. We are working to understand the origin of the polarization change across the sharp sodium lines, which may be an artifact of the reduction process rather than a real effect. Further work will be required to understand the implications of this result. A fragment of the polarization spectrum of a variable star R CrB is shown in Figure 2. Both the narrow and broad components of the sodium doublet at 5890 and 5896 A, originating in the circumstellar medium, are seen. The polarization level of these emission lines is the same as in the nearby continuum. Studies of such spectra may provide insight into the understanding of the R CrB phenomenon. A fragment of the polarization spectrum in the H-alpha region of a Be star is shown in Figure 3. The polarization level of the emission line core is decreased with respect to the broad wings and to the nearest continuum, as is expected for depolarization effects due to increased emission of H-alpha in the circumstellar envelope. (Panchuk V.E., Yushkin M.V.)

Other science efforts for the project were also continuing, as described in the following items:
In the previous quarter the spectra of the peculiar object IRAS 19475+3118 (associated with the star HD 331319) were analyzed. The fundamental parameters and detailed chemical composition of the object were determined. In the spectrum of this high luminosity object (Mv < -8 mag.) with an effective temperature of approximately 7250 K, helium lines were found to indicate a significant helium excess in the outer atmospheric layers. This may be evidence of possible helium synthesis during the course of previous evolution. More details were presented in the previous report. V.G. Klochkova, V.E. Panchuk and N.S. Tavolganskaya prepared the paper "HD331319 - post-AGB F-supergiant with HeI lines in the spectrum", which was submitted and accepted by the Russian journal "Astronomy Reports" and will be published in January 2002.
The work on the spectral atlas of super- and hypergiants was continued in connection with obtaining new spectra of HD 183143, HD 168607, AS 314 and HD160529 in June 2001. The last star (HD 160529) was also included in the atlas. The atlas is ready for publication: Chentsov E.L., Ermakov S.V., Klochkova V.G., Panchuk V.E., Bjorkman K., Miroshnichenko A.S. "Spectral atlas of of B2-B6 hyper- and supergiants in 4800-6700 AA". Preprint Spec. Astrophys. Observ., 2001. In addition, 19 spectra of HD168625, HD168607 and AS314 obtained from 1992 up to 2001 were prepared for modeling of their line profiles, aiming at a study of their stellar winds. All these spectra, as well as spectra of stars observed on the program "Young intermediate-mass stars" were processed in MIDAS system (Chentsov E.L., Klochkova V.G., Ermakov S.V.).
As discussed in the previous report, we reduced and analysed two high resolution spectra of the faint evolved star K413, a member of the globular cluster M12. It should be noted here that our spectra are the first high resolution spectra for members of M12 at all. Based on results derived for the star K413 during the reporting fourth period we wrote up a paper for submission to A&A. The paper "K413, a star near the AGB in the globular cluster M12" by V.G. Klochkova and N.N. Samus has been accepted by A&A.
We completed a study of the emission-line A-type star IP Per based on the results of high- and low-resolution spectroscopic and broadband multicolour photometric observations. The high-resoltuion data were obtained with the echelle spectrographs LYNX and PFES. The star's fundamental parameters were derived as follows: Teff approximately 8000 K, log g approximately 4.4, log L/Lsun approximately 1.0. We also found that the metallicity of the object's atmosphere is nearly 40 per cent that of the Sun. Our result for the star's gravity implies that it is located at the zero-age main-sequence. We conclude that IP Per is a pre-main-sequence Herbig Ae star, and belongs to the group of UX Ori-type stars showing irregular photometric minima. These results were reported in the paper "The pre-main-sequence star IP Per" by A.S.Miroshnichenko, K.S.Bjorkman, E.L.Chentsov, V.G.Klochkova, R.O.Gray, P.Garcia-Lario, and J.V. Perea-Calderon. The paper was accepted by A&A.
Main optical elements for the spectropolarimeter of the prime focus of the 6-m telescope (echelle grating, cross-dispersion prisms, camera lenses, half-wave and quarter-wave plates) were produced and acquired. Two modes of the cross dispersion unit (classical echelle spectrograph mode and spectropolarimetric mode) were tested in the laboratory. In the first mode the echelle frame covers the range 3900-9000 AA and the range 4000-7000 AA in the second mode. Parameters of the new spectral device will be essentially improved in comparison with the existing echelle spectrometer PFES: the spectral resolution will be increased by 1.4 times, the number of spectral elements registered by 1.7 times, and the throughput by 2 times. The spectropolarimetric mode will allow us to measure both linear and circular polarization. (Panchuk V.E.)
Based on a review of published information on stellar spectro- polarimeters, a program to develop equipment for stellar spectro- polarimetry at the 6-m telescope is proposed (Klochkova V.G., Panchuk V.E., and Romanenko V.P. Stellar spectropolarimeters. Preprint SAO N156, 2001).

The fifth period

During the time of this report, the reciprocal visit of the FSU team to the U.S. occurred. The FSU team (V. Klochkova and V. Panchuk, Special Astrophysical Observatory) visited the Ritter Observatory of the University of Toledo, Toledo, OH, USA. The travel was funded from the CRDF award to the FSU team. The visit at the Ritter Observatory lasted over 3 weeks in November 2001. While meeting together, we continued discussions of the collaborative science projects that are underway. Discussions about options for introducing polarizing optics to the high resolution spectrometer NES, recently developed at the 6m telescope by V.Panchuk, have also been held. We have discussed the results of the data reduction and calibration for some polarization standards observed at the 6m telescope with the Prime Focus Echelle Spectrograph (PFES) through a linear polarization analyser. We also discussed the data reduction pipeline and interpretation of the data obtained in the framework of the CRDF project. Plans for follow up observations and suggested calibration tests were made. We discussed forthcoming joint publications. Preparations for a poster paper describing our joint project (to be presented at the January 2002 meeting of the American Astronomical Society) were carried out.
A seminar on spectroscopic and spectropolarimetric devices at the 6m telescope was presented on November, 15, 2001. Primary astrophysical results from the FSU team, based on the observational data obtained with the devices mentioned above, concerning post-AGB stars, A- and F-supergiants, and hypergiants were reported.
The FSU team visited the Catholic University of Valparaiso (Valparaiso, IN) aiming at a joint scientific discussion on proto-planetary nebulae with Prof. B. Hrivnak, a well-known researcher in this field. The FSU team's results on high resolution spectroscopy of such objects were presented there. These results are significant to understanding the processes of stellar nucleosynthesis and evolution of intermediate-mass stars after the main sequence phase.
During the visit, the FSU team was acquainted with spectral devices at the Ritter Observatory and software for 2-dimensional spectra processing. We have discussed advantages of the packages used for spectroscopic data reduction at the Ritter Observatory and at the Special Astrophysical Observatory.
We have also discussed a possibility to use new observational facilities at the 6m telescope to select new targets for follow up high resolution spectroscopy.

Science efforts for the project are continuing, as described in the following paragraphs.
During the period reported we reduced and analyzed new spectra of the peculiar hypergiant IRC+10420, associated with a very distant IR-source, one of the brightest in the sky at 20 microns, whose spectral monitoring has continued at the 6m telescope since 1992. A strong double-peaked emission in the H-alpha line was found in 1985 and explained in terms of a rotating equatorial disk model, first proposed by Jones et al. (1993) for this object. All the spectra we obtained between 1992 and 2000 contained a complex emission-absorption H-alpha profile, many emission lines of FeI, FeII, TiII, CrII, ScII, as well as forbidden lines of [OI], [FeII], and [CaII]. Both emission and absorption lines show a correlation between their radial velocities and oscillator strengths. Variability of the relative intensities of the H-alpha and H-beta emission components was found. All optical spectra of IRC+10420 show the HeI 5876 A absorption line with a large equivalent width of not less than 200 mA, which might indicate an evolutionary helium enhancement. Based on high resolution optical spectra we obtained in 1995, the effective temperature Teff=8500K has been estimated for IRC+10420. Based on the optical spectrum of 2000 we estimated its spectral type as A2, which corresponds to Teff=9200 K. The strength of the OI IR-triplet at 7774 A led us to a luminosity estimate of Mbol=-9.5 mag. We concluded that IRC+10420 is rapidly evolving to the Wolf-Rayet stage. The average rate of the temperature increase over more than 25 years is 120 K a year, with a current rate of 160 K a year. These results have been accepted by Astronomy Reports for publication in January 2002 (V.Klochkova, M.Yushkin, E.Chentsov, V.Panchuk).
We completed a study of the emission-line star AS 381 based on the results of optical and near-IR spectroscopic and broadband multicolor photometric observations. The spectrum of AS 381 indicates the presence of both a hot (early B-type) and a cool (K-type) star in the system. A high interstellar reddening (\approx 7 mag.) suggests that it is located at a distance greater than 3 kpc, and the companions have luminosity types II or higher. The emission-line profiles indicate that the system is surrounded by a flattened circumstellar envelope, which is viewed close to pole-on. The hot companion is found to be approximately 2 mag. brighter in the V-band and more massive (approximately 20 Msun) than the cool one (approximately 7 Msun). The strong line emission and the position of the companions in the Hertzsprung-Russell diagram indicate that the system is experiencing mass exchange. We suggest that AS 381 is the first B[e] supergiant binary discovered in the Milky Way. The results are presented as a paper, accepted for publication by Astronomy and Astrophysics (A.S.Miroshnichenko, K.S.Bjorkman, E.L.Chentsov, V.G.Klochkova, O.V.Ezhkova, R.O.Gray, P.Garcia-Lario, J.V. Perea-Calderon, R.J.Rudy, D.K.Lynch, S.Mazuk, C.C.Venturini, R.Puetter).
We began preparation of a spectral atlas, which includes spectra of 3 post-AGB stars of different effective temperatures at different phases of evolution after AGB.
The optical elements for the prime focus spectropolarimeter were tested in a laboratory conditions.

The 6th period

The project continues, with discussions between the US and FSU teams being carried out via e-mail. We fulfilled 2 observing runs at the 6-meter telescope, using the high resolution spectrometer NES, and obtained high resolution spectra for the program stars IRAS01005+7910 and CI Cam, and for several standards. Main science efforts were directed to preparation of several joint papers and reports, as described below.
We finished a paper reporting the results obtained during an initial phase of the spectroscopic monitoring of a poorly-studied proto-planetary nebula (PPN) candidate IRAS01005+7910 at the 6-m telescope of the Russian Academy of Sciences. Its IRAS colors are similar to those of PPNe. However, in contrast to most of the PPNe, the maser emission from IRAS01005+7910 has been detected neither in CO nor in OH bands. So far only low-resolution spectra of IRAS01005+7910 have been published, where the object was classified as a B2Ie star. For the first time, we accomplished a careful spectral line identification and measured the line parameters in the spectra of IRAS01005+7910. As a result, significant variability of the optical spectrum was detected. We found absorption lines of CII, OII, NII, AlII, SiIII, and MgII (4481A), as well as emission lines of SiII and [FeII]. Both absorption and emission components are present in the Balmer lines, NaI resonance D-lines, HeI, and FeIII lines. The HeI line profiles vary from straight to inverse P Cyg-type on a timescale of days to months. The resonance NaI lines show 5 absorption components at a resolution of R=60000. Additionally, the NaI D2 line exhibits a variable emission component with a width comparable to that of the Balmer line emission components. We estimated the MK type of IRAS01005+7910 as B2Ia (T_eff about 21000 K). We suggest that IRAS01005+7910 is a high-luminosity early-B type star, surrounded by a non-spherical gaseous envelope with both observable accretion and outflow. The envelope geometry and weakness of the emission-line spectrum may indicate binarity of the system. The object is most likely located at the horizontal evolutionary track on its way to the PN region. The paper "Discovery of spectral variations of the optical counterpart of IRAS01005+7910" by V.G.Klochkova, M.V.Yushkin, A.S.Miroshnichenko, V.E.Panchuk, and K.S.Bjorkman, was submitted to A&A on 2002 March 1.
Based on multicolour photometry and spectroscopy both in the optical and IR-region obtained at several telescopes, we tried to clarify the nature and evolutionary state of the peculiar emission-line star V669 Cep=IRAS22248+6058. The optical spectrum of V669 Cep is remarkable due to extremely strong and variable emission in the H alpha line. The presence of forbidden lines in the spectrum allows us to classify V669 Cep as a B[e] object, a new member of the category of Be stars with warm dust. Overall, the results of our observations suggest that V669 Cep is most likely a mass-exchanging binary system with both hot (B4-B6 low-luminosity star) and cool (K-type star) stellar components surrounded by a non-spherical gaseous-and-dusty envelope. The cool component manifests itself through CN and CO absorption bands in the near-IR spectrum. The spectrum and spectral energy distribution of V669 Cep are similar to those of another binary Be star (AS381) that we studied earlier. The paper "V669 Cep: A new binary system with a B[e] star" by A.S.Miroshnichenko, K.S.Bjorkman, Chentsov E.L., V.G.Klochkova, N.Manset, et al. was submitted to A&A on 2002 February 28.
Spectroscopic (resolving power R=60000) and spectropolarimetric (R=15000) observations of the northern lobe of the Egg nebula (AFGL2688) were performed at the 6-meter telescope. Recent results published by Klochkova et al.(2000, Astronomy Letters) confirmed the post-AGB evolutionary state for the central star of this object.
The combination of spectroscopy and spectropolarimetry permits us to separate optical spectral components formed in the stellar atmosphere from those formed in the nebula. We showed that the approximation of single scattering of optical radiation is valid within the nebula. The optical spectrum of the nebula contains emission components of the resonance sodium doublet NaI D1&2, emission in H alpha, and emission bands of the C2 molecule. We showed that the nebula is optically thick in the lines of the sodium doublet. A system of absorptions found in the resonance sodium line confirms a continuation of the matter outflow from the star. We resolved the rotational structure of the emission bands of the Swan system of the C2 molecule. Our analysis of both the rotational spectrum and vibrational-rotational transitions of the C2 molecule confirms a hypothesis about the resonance fluorescence as their exciting mechanism, which was proposed earlier by Klochkova et al. (2000).
A macroturbulence velocity in the atmosphere of the central star was estimated. Radial velocities were measured using spectral details formed both in the photosphere of the supergiant and inside the lobe. An analysis of the optical data was carried out in combination with published results based on the radio- and IR-regions. We critically considered models suggested for the nebula AFGL2688. It should be noted that high resolution spectropolarimetry for such a faint object (V>14.5mag) was obtained for the firts time.
The paper "Nebula AFGL2688: spectroscopy and spectropolarimetry with high spectral resolution", by by V.G.Klochkova, V.E.Panchuk and M.V.Yushkin, will be submitted to Astronomy Reports soon.
The processing of the results of spectroscopic monitoring of the LBV object HD168607 is completed. Between 1992 and 2001 we obtained 11 high-resolution spectra using CCD-echelle spectrometers of the 6-m telescope of SAO RAS from 1992 through 2001. HD168607 is a unique hypergiant that can be a key object in our understanding of the LBV phenomenon. Its photometric behaviour shows evidence of both pulsations in the photosphere and "pseudo-photospheric" processes in its wind. We have revealed the spectroscopic manifestations of both these processes. The absorption lines of HeI, light ions, and FeII lines of high excitation indicate the variable velocity gradient in the photosphere, while variable multicomponent PCyg profiles of hydrogen and FeII lines of low excitation give valuable information about the variable and non-spherical wind. This gives an additional argument in favour of adding HD168607 to the LBV group. However, the important signatures of an LBV denoted by an optical nebula and IR excess have not been discovered in this object yet. We hope to understand the nature of HD168607 by means of line profile modeling and of a direct comparison of its spectrum with the spectra of the recognized LBVs of relatively low luminosity, such as HR Car, R40, HD160529. (The paper by Miroshnichenko A. and Chentsov E. is now under preparation).
A new joint paper by A.S.Miroshnichenko, K.S.Bjorkman, Chentsov E.L., V.G.Klochkova, et al. "The Luminouis B[e] Binary AS 381" was published in A&A (v.383, p.171, 2002). In this paper we reported our finding of the first B[e] binary supergiant in the Milky Way.
Development of the new spectropolarimeter for the prime focus of the 6-m telescope was continued during the last quarter. Aspects of the work during this time include: a specification for manufacturing of mechanical units to be incorporated in a prime focus spectropolarimeter. This work will be paid as a subcontract (Panchuk V.).