COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      Number 1088

                                 Konkoly Observatory
                                 Budapest
                                 1976 January 25



    NEW OBSERVATIONS OF THE WHITE DWARF ECLIPSING BINARY
                      V 471 TAURI


    The eclipsing nature of the V 471 Tau (BD + 16d516) was 
announced by Nelson and Young (1970). They have shown that it is an
eclipsing binary consisting of a K0V star and a white dwarf. Hills
(1971) calculated the temperature and luminosity of the white dwarf
companion. In 1972, Vauclair investigated the evidence of mass loss
from the system and the mass transfer between the components, and
also showed that the system is a member of the Hyades cluster. Later 
on, a detailed analysis were made by Young and Nelson (1972).
    We have observed this interesting close binary system during
ten nights between 1973 and 1975 with the 48 cm Cassegrain telescope 
of the Ege University Observatory. A RCA 1P21 photomultiplier
was used with B and V filters of the UBV system in these 
observations.
    Four times of primary minima were obtained in blue light and
are given in the following Table:


Min (hel.)         O-C
-----------------------
2442006.3140     0.0000
387.301          +.002
720.334          -.001
723.464          +.002
-----------------------


The O-C values and the phases of the observations were calculated
with the following elements given by Warner et al. (1971):
      
    Min JD 2 440 970.723705 + 0.52118286d . E.

    The star BD + 16d515 was chosen as a comparison, BD + 16d524
and HD 24040 as check stars. The comparison star was observed with
the check stars two or more times in each night. No variations in
the brightness of the comparison star were observed. All the 
observations were corrected for differential extinction.
    The light curves of the system are shown in Figures 1, 2, 3
and 4. The light curves, obtained in 1973, are similar with those
of Nelson and Young (1970). Only, the difference in brightness 
between the maximum and mid-primary minimum is decreased about 0.1m
in two colors. The 1974 and January 1975 light curves are 
disappointing. The shape of the curves is distorted and the shift in
the phases is clearly seen. On the other hand the system is
brighter on the order of 0.14m in 1974 and 0.07m in January 1975
than in the year 1973. The November 1975 light curves show many
characteristics of an intrinsic variable. The brightness of the
system at the occultation of the hot companion is not constant,
a steady decline has appeared. Following the primary minimum
there is a constant light about 0.2 phase interval. The brightness 
of the system reaches a minimum approximately at phase 0.45.
Thereafter a steady brightening is seen.
    A successful model to explain the variations in shape and
the shape of such a light curve of the system is not yet known.
Only the intrinsic variability of the K0V star may be suggested.



                            CAFER IBANOGLU
                        Ege University Observatory
                              P.K. 21
                         Bornova-Izmir, Turkey



References:

Hills, J.G.    Pub.A.S.P. 83, 81. 1971. [BIBCODE 1971PASP...83...81H ]
Nelson, B. and Young, A. Pub.A.S.P. 82, 699. 1970. [BIBCODE 1970PASP...82..699N ]
Vauclair, G. Astron.and Astrophys. 17, 437. 1972. [BIBCODE 1972A&A....17..437V ]
Warner, B. Robinson, E.L. and Nather, R.E. Mon.Not.R.Astr.Soc.
   154, 455. 1971. [BIBCODE 1971MNRAS.154..455W ]
Young, A. and Nelson, B. Ap.J. 173, 653. 1972. [BIBCODE 1972ApJ...173..653Y ]


                      [FIGURE 1]
                      [FIGURE 2]
                      [FIGURE 3]
                      [FIGURE 4]