COMMISSIONS 27 AND 42 OF THE IAU
            INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3895

                                          Konkoly Observatory
                                          Budapest
                                          11 June 1993

                                          HU ISSN 0374 - 0676


         LIGHT CURVE PECULIARITIES OF AS 442=NSV 13308


Herbig Ae/Be star AS 442=NSV 13308 lies close to V517 Cyg, AS 441, LkH alpha
134, 135 and other Herbig Ae/Be stars in the extensive star forming region 
RSF 4 Cyg B associated with NGC 7000/IC 5070 (Shevchenko et al., 1988).

The spectral type of B3-A0 was assigned to AS 442 (Finkenzeller, 1985;
Shevchenko, 1989), H alpha emission line EW=18-23 angstrom, double peak type
(Finkenzeller and Mundt, 1984) and strong polarization near light maximum,
P_v=3% (Petrova and Shevchenko, 1987) are present.

Our observations of AS 442 were made in 1984-1991 on Mt. Maidanak using a 0.5
m, reflector with UBVR pulse counting photometer. Two 100 angstrom/mm
spectrograms were obtained in June 1990 using the Byurakan 2.6-m reflector
"ZTA" with UAGS spectrograph equipped with an image tube.

800 UBVR-magnitudes were measured during 8 years of observations.
Observational data are listed in Table 1. The summary light curve is plotted
in Figure 1. Figure 2 shows the annual light curves for 1988-1991. The same
data for 1984-1985 can be found in Shevchenko (1989). The annual light curves
for 1986-1987 are similar to the light curve for 1988.

The light curves contain Algol-like nonperiodic minima and waves of different
durations. The periodicity of AS 442 light curve is analysed by modern methods
of digital spectral analysis (Marple, 1987). A reliable period is not found
but there are a number of low possibility (Pi) periods, e. g. P=16.2 day,
Pi=0.76, V=0.2m, on 1984-1985 epoch.


                             [FIGURE 1]

          Figure 1. The summary light curve of AS 442

                             [FIGURE 2]

          Figure 2. The light curves of AS 442 for 1988-1991

                             [FIGURE 3]

          Figure 3. Fragments of the spectra of AS 442


          Table 1. AS 442 photometry data for 1984-1991.

Year   Epoch           n       V          <V>   <U-B>   <B-V>   <V-R>
       JD 2440000+
1984   5879-6061      69   10.89-11.44   11.03   0.35    0.67    0.72
1985   6255-6383      63   10.81-11.30   10.96   0.34    0.67    0.73
1986   6613-6802      54   10.91-11.28   11.01   0.32    0.68    0.74
1987   6958-7124      90   10.87-11.07   10.96   0.31    0.65    0.72
1988   7307-7507     147   10.89-11.13   10.96   0.29    0.66    0.72
1989   7677-7887     136   10.82-11.57   11.07   0.31    0.68    0.74
1990   8048-8271     138   10.88-11.67   11.12   0.34    0.69    0.75
1991   8419-8586     103   11.07-11.78   11.32   0.33    0.72    0.78

The annual average and minimum V values decreased from 1989 to 1991. No
analogous case was found in the photometric history of AS 442.

The spectral fragments are plotted in Figure 3. It shows the relative
intensity of CaII K-line and complex line H epsilon+CaII H, H beta line with
emission component and three strong FeII-lines:  4924, 5018 and 5169.

The spectral type of AS 442 on 28 June 1990 was A2-3 IV-III, E_B-V=0.60m,
E_V-R=0.65m, A_v=2.0m. Intrinsic stellar excess (without interstellar
extinction) E_U-B*=-0.3m, seems to be caused by circumstellar dust scattering.
The light curve of Herbig Ae-star AS 442 is similar to that of V517 Cyg
(Abramian et al., 1990) and V373 Cep (Shevchenko et al., 1991).


                          S. Yu. MELNIKOV,
                          V. S. SHEVCHENKO,
                          K. N. GRANKIN,
                          M. A. IBRAGIMOV,
                          S. D. YAKUBOV
                          Tashkent Astronomical Institute,
                          Uzbekistan Academy Sci.,
                          Astronomical st. 33
                          Tashkent 700052,
                          Uzbekistan

References:

Abramian, G. V., Zaratsian, S. V., Melikian N. D., Melnikov, S. Yu., Shevchenko, V. S.,
   1990, Astrofisika, 32, 39 [BIBCODE 1990Afz....32...39A ]
Finkenzeller, U., 1985, Astron. Astrophys., 151, 340 [BIBCODE 1985A&A...151..340F ]
Finkenzeller, U., Mundt, R., 1984, Astron. Astrophys. Suppl., 55, 109 [BIBCODE 1984A&AS...55..109F ]
Marple, S. L., 1987, Digital spectral analysis, Prentice-Hall, New Yersey [BIBCODE 1987ph...book.....M ]
Petrova, N. N., Shevchenko, V. S., 1987, Sov. Astr. Lett., 13, 686 [BIBCODE 1987SvAL...13..289P ]
Shevchenko, V. S., 1989, Herbig Ae/Be stars, Tashkent, "Fan", p. 151 [BIBCODE 1989has..book.....S ]
Shevchenko, V. S., Grankin, K. N., Melnikov, S. Yu., 1988, Sov. Astr.-A. J., 65,1230 [BIBCODE 1988SvA....32..641S ]
Shevchenko, V. S., Grankin, K. N., Ibragimov, M. A., Melnikov, S. Yu., Yakubov, S. D.,
   Melikian, N. D., 1991, IBVS, No. 3628