COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 2875
 

                                         Konkoly Observatory
                                         Budapest
                                         12 March 1986

                                         HU ISSN  0374 - 0676



  PHOTOELECTRIC UBV OBSERVATIONS OF AQ Tau AND THE PROBLEM OF ITS PERIOD


  The variability of this star was discovered by Hoffleit (1939). Kurochkin
(1951) lists this star as having an Algol type light curve and light elements:
J.D. hel. 2429651.348 + 1.215904d E. According to the GCVS its spectral type
is A5.
  UBV photoelectric observations of AQ Tau were made using the 0.91 m
reflector and a photoelectric photometer at McDonald Observatory from Nov.
1984 to Jan. 1985.
  The comparison star a was used according to the chart given by Kurochkin
(1951) (see Figure 1). Over 1494 observations in U, B, and V for 17 nights
have been obtained and delta magnitude curves are shown in Figure 2. The
light curves indicate that the components form an Algol type binary.


                                [FIGURE 1]

                     Figure 1. Identification chart


   It is noteworthy that we hardly find any secondary minimum according to
the period of 1.215933 which was listed in the GCVS.
  According to the light curves we consider that the period of AQ Tau is
2.431808, i.e. two times longer than the original period. The two components
are almost equal in temperature.

   The light elements are as follows:

         Min. = J.D. Hel. 2446012.94513 + 2.431808d E


                 [FIGURE 2] 

 Figure 2  The light curve of AQ Tau with P0
                                             [FIGURE 3]
                           Figure 3  The light curve of AQ Tau with 2P0



          LIU XUEFU                          TAN HUISONG

       Department of Astronomy            Yunnan Observatory
       Beijing Normal University          Academia Sinica
       Beijing, China                     Kunming, China




References:
Hoffleit, D., 1939, Harvard Bull., Nos. 901-911. [BIBCODE 1935BHarO.901...20H ]
Kurochkin, H.E., 1951, Perem. Zvezdy, 8, 351. [BIBCODE 1951PZ......8..351K ]
Kukarkin, B.V. et al., 1969, General Catalogue of Variable Stars. [BIBCODE 1969gcvs.book.....K ]