COMMISSION 27 OF THE I. A. U.
      INFORMATION BULLETIN ON VARIABLE STARS
                  Number 1613

                                  Konkoly Observatory
                                  Budapest
                                  1979 May 28

         REVISED PHOTOMETRIC ELEMENTS OF AY CAM



      The eclipsing binary AY Camelopardalis was discovered by
Strohmeier and Knigge (1961), and was observed during the years 1966-
1968 by Tempesti (1969), who found out that the period of the variable
is 2.7349658d, i.e. twice the one found earlier.
       Tempesti also obtained a solution for the photometric and
geometric elements using the procedure of Russell and Merrill (1952),
assuming primary minimum is due to an annular eclipse, but found some
departure of the model from the true system.
       Using the normal points given by Tempesti (1969), reduced
to 100 points in order to save computing time, we have calculated a
set of photometric and geometric elements for AY Cam with the method
by Wood (1971, 1973-1978). The solution, shown in the table, confirms
the annular type of the eclipse occurring at primary minimum.


       Table*)

 adjusted parameters           fixed parameters

i      = 88.0d+-0.2            log g_1   = log g_2  = 4.3
r_1    = 0.221+-0.001          w_1 = w_2 = 0.5
kappa  = r_2/r_1=0.747+-0.002  n_1 = n_2 = 5.0
beta_1 = 0.080+-0.023          auxiliary parameters
beta_2 = 0.080+-0.054          a_1 = 0.225      a_2 = 0.167
x_1    = 0.6+-0.2              b_1 = 0.222      b_2 = 0.166
x_2    = 0.6+-0.2              c_1 = 0.220      c_2 = 0.165
T_1,eq = 6890 dK +- 10     T_1,pol = 6910 dK
T_2,eq = 7000 dK +- 10     T_2,pol = 7020 dK
q=m_2/m_1=0.83+-0.10           L_1 = 0.626
                               L_2 = 0.374

  for the explanation of the symbols used, see Wood (1971); also
  Mancuso et al. (1978).


                           [FIGURE 1]

      The value of the mass ratio, although poorly determined,
gives for the quantities y_11, y_12 of the Roche lobes the values 0.391
and 0.357, respectively (Plavec and Kratochvil, 1964). A comparison
with the semi-axis of the components reveals that AY Cam is a normal
detached system, made of two main sequence stars, which are well inside 
their respective critical lobes. The values of the temperature 
correspond to two F0-F2 stars, as indicated by the B-V curve of Tempesti
(1969). In the figure we give the computed lightcurve, plotted among
the observed normal points, and the detail of the O-C (in magnitude
units) obtained. In contrast with the most complete model we adopted,
the non-random distribution of the O-C`s displays the existence of some 
effect which has not yet been identified.
      An accurate multicolour photometry, as well as spectrographic 
observations, are needed in order to get a better comprehension
of the physical conditions of this system,



                    L. MILANO and G. RUSSO
                    Capodimonte Astronomical Observatory
                    via Moiariello, 16
                    I-80131 Napoli- Italy


References


Mancuso S., Milano L. and Russo G.: 1978, Astron. Astrophys. 63, 193 [BIBCODE 1978A&A....63..193M ]
Plavec M. and Kratochvil P.: 1964, Bull. Astron. Inst. Czechosl. 15, 165 [BIBCODE 1964BAICz..15..165P ]
Russel H.N. and Merrill J.E.: 1952, Contr. Princeton no 26 [BIBCODE 1952deeb.book.....R ]
Strohmeier W. and Knigge R.: 1961, Bamberg Mitt.Verand. Sterne 5, n. 10
Tempesti P.: 1969, Mem. Soc. Astron. It. 40, 345 [BIBCODE 1969MmSAI..40..345T ]
Wood D.B.: 1971, Astron. J. 76, 701 [BIBCODE 1971AJ.....76..701W ]
Wood D.B.: 1973-1978, Wink Status Report no. 1-9 (circulars).