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\IBVShead{4112}{15 November 1994}                      % Use it with dummy or empty arguments

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\centerline{\ft A NEW V/R CYCLIC CHANGE OF H${\alpha}$ in $\zeta$ Tau}
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Since the late 1970s, we have monitored the object. The observations reported
in this paper were made with the grating spectograph of the 2.16 m telescope
at the Xinglong Station of Beijing Astronomical Observatory during 1990 
December - 1994 April. The detector was a CCD with 512$\times$512 (or 
576$\times$384) pixels. The reciprocal linear dispersion of the spectra was
50\AA\ mm$^{-1}$ at H${\alpha}$. One pixel corresponds to 1.35\AA\ (or 1.15\AA).
The S/N-ratio at the continuum was $>$150. The observational and data reduction
techniques have already been described by Guo and Guo (1992). Our results showed
that the H$\alpha$ profiles underwent a cyclic change (c.f. Figure 1). The 1990
December 25 H$\alpha$ profile appeared as a single emission peak of asymmetric 
top and no visible central reversal. The profiles become distinct double
emission peaks during 1991-1993. It is of interest to note that the 1994 April
28 profile become again a single emission peak, such as on 1990 December 25. In 
addition, the V/R ratio of H$\alpha$ was larger (in 1990), equal to (around the
beginning of 1992) and less (during 1992 November and 1993 October) than 1. 
Table 1 lists the results of the H$\alpha$ measurements in the different observing
periods. Throughout our observations no appreciable change in the H$\alpha$
profiles obtained within each night has been detected. Hence we show only the mean
profile measurements for each given night. It can be seen from the table that
the equivalent width (W$\alpha$) and the full-width-at-half-maximum (FWHM) reached
the maximum when the violet emission component is equal to the red one, and that the 
intensities (I$_v$) of the violet emission component declined gradually, while the 
intensities (I$_r$) of the red one rose slowly during our observing period.
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\centerline{Table 1}
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\begin{tabular}{ccccccc}
\hline
Date\ \ \ \ \ &No. of&W$\alpha$&FWHM&I$_v$&I$_a$&I$_r$\\
UT&profiles&(\AA)&(\AA)& & & \\
\hline
\\
1990 Dec 25.727&5&$-$19.7&10.69& &(2.40)$^{\star}$& \\
1991 Oct 09.876&20&$-$20.1&10.69&2.96&1.60&2.17\\
1991 Dec 16.674&15&$-$22.5&10.69&2.85&2.02&2.30\\
1991 Dec 27.717&4&$-$22.3&10.69&2.78&2.02&2.24\\
1992 Feb 26.620&4&$-$24.4&11.08&2.78&2.02&2.66\\
1992 Feb 27.644&6&$-$23.8&11.04&2.78&2.03&2.65\\
1992 Nov 14.804&3&$-$23.8&10.50&2.52&2.04&3.25\\
1992 Nov 15.809&6&$-$24.0&10.32&2.52&2.06&3.33\\
1993 Oct 28.659&2&$-$21.8&10.52&2.09&1.95&2.84\\
1994 Apr 28.495&6&$-$22.3&10.50& &(2.69)$^{\star}$\\
\hline
\end{tabular}
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\centerline{$\star$ values in paranthesis are central intensity of the emission line}

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\centerline{2}
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\centerline{Figure 1}
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Since the beginning of 1960s, the cyclic variations of the radial velocity
of the Balmer absorption lines and the V/R ratio of the Balmer emission lines
have been observed successively in the star on numerous occasions (Hubert-Deplace
et al., 1982). Mon et al. (1992) showed the cyclic variations had terminated and 
the star seemed to have entered a new quiet phase around 1982. Our spectroscopic
observations also indicate that the V/R cyclic variations of H$\alpha$ had
vanished since 1982 (Yulian Guo et al., 1994). Our results show that after their 
disappearance for several years, a new V/R cyclic variation of H$\alpha$ emerged
once again at the end of 1990 and lasted for about 3.5 years. It seems that the
cyclic variations of the star were very complicated, not only the duration and
the amplitude of each cycle are different but the cyclic variation is sometimes
disappearance and at other times reappearance. Therefore, it is necessary to make
further observations and discussions.
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% Call for macros \authors - \authorsrightcol - \endauthors
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YULIAN GUO
Beijing Astronomical Observatory
Chinese Academy of Sciences
Beijing, China
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\references

Guo Yulian, Guo Xiozhen, 1992, {\it Inf. Bull. Var. Stars}, No.\,3786

Guo Yulian, Huang Lin, Hao Jinxin, Cao Huilai, Guo Zihe, Gou Xiaozhen, 1994,
in preparation

Hubert-Deplace, A. M., Jaschek, M., Hubert, H., Chambon, M. Th., 1982, 
{\it IAU Symp.}, {\bf 98}, 125, in: Jaschek, M.,
Groth, H. G., (eds.), Be stars
%Changed: Tue Jun 14 15:32:23 MEST 2005

Mon, M., Kogure, T., Suzuki, M., Singh, M., 1992, {\it PASJ}, {\bf 44}, 73



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