COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                       Number 2718

                                           Konkoly Observatory
                                           Budapest
                                           13 May 1985

                                           HU ISSN 0374 - 0676

           PHOTOMETRIC BEHAVIOR OF HR 8752 = V509 Cas

   One of the most luminous of all galactic stars, the supergiant HR 8752 is
a known light and spectrum variable. The spectral type has been observed to
change from G0 Ia in 1950 to G5 in 1970 (Keenan, 1971) to K2-5 Ia in 1973 and
finally to late F by 1977 (Lambert and Luck, 1978). Evidence for a
hotter companion (approximate spectral type B1 V) was found in IUE low 
resolution spectra by Strickland and Harmer (1978). Shorter term variations in
various spectral features have been reported by various observers (e.g.,
Smolinski et al., 1979 and Barden and Ramsey, 1980).
  Photometrically, the star varies in V and (B-V) magnitudes in a manner which
appears to be uncorrelated with the spectral changes. The previous photometric
behavior is well summarized by Walker (1983). Briefly, the star has been found
to slowly vary in an irregular fashion from V = 4.6 to 5.4 and in (B-V) from
+1.29 to 1.73. Shorter variations on the time scale of days are not ruled out.
  HR 8752 was observed on 22 nights during July, 1984 to February, 1985 in
B and V magnitudes with the 0.6-m telescope of the Corralitos Observatory. The
single channel photon-counting photometer is equipped with an uncooled EMI
9924A photomultiplier tube. Comparison stars were HR 8761 (V = 6.20; B-V =
+1.50) and HR 8778 (V = 6.43; B-V = +0.90). The observations were corrected
for extinction and converted to BV magnitudes by observations of standard
stars. Standard errors for the comparison stars of +\- 0.01 in both DeltaV and
Delta(B-V) for each night's observations were noted.

                               Table I
         JD                        JD
      (240000+)  V     (B-V)    (2440000+)    V       (B-V)
      5911.9045 4.86   +1.35   6025.6938    4.88      +1.31
      5939.7865 4.81    1.32   6029.6028    4.89       1.32
      5957.7778 4.81    1.33   6031.5931    4.88       1.33
      5959.8042 4.82    1.32   6034.6069    4.90       1.33
      5961.7111 4.82    1.33   6050.6201    4.90       1.38
      5962.7802 4.82    1.32   6082.5951    4.91       1.37
      5964.7243 4.83    1.28   6083.5878    4.93       1.39
      5967.7049 4.82    1.30   6084.6024    4.94       1.37
      5985.6639 4.83    1.31   6085.5990    4.94       1.37
      6009.6368 4.86    1.30   6101.5854    4.97       1.38
      6012.6170 4.87    1.31   6102.6066    4.98       1.38





  Over the period in question, HR 8752 was found to vary in a smooth fashion
from a maximum of V = 4.81 to a minimum of 4.98 and in (B-V) from +1.28 to
+1.39. Figure 1 shows these changes and Table I their values. The variation
in (B-V) appears to approximately follow the V magnitudes.



                             [FIGURE 1]

 Figure 1: Variations in V and (B-V) magnitudes for HR 8752 = V509 Cas.



                            E.M. HALBEDEL
                            Corralitos Observatory
                            P.O.Box 16314
                            Las Cruces, NM 88004 USA





References:

Barden, S.C. and Ramsey, L.W. (1980), Publ.Astr.Soc.Pacific, 92, 497. [BIBCODE 1980PASP...92..497B ]
Keenan, P.C. (1971), Contr.Kitt Peak Nat.Obs., No. 554.
Lambert, D.L. and Luck, R.E. (1978), Mon.Not.Roy.Astr.Soc., 184, 405. [BIBCODE 1978MNRAS.184..405L ]
Smolinski, J., Climenhaga, J.L. and Funahawa, H. (1979), IAU Circ. No. 3382 [BIBCODE 1979IAUC.3382....2S ]
Strickland, D.J. and Harmer, D.L. (1978), Astr. and Ap., 70, L53. [BIBCODE 1978A&A....70L..53S ]
Walker, E.N. (1983), Mon.Not.Roy.Astr.Soc., 203, 403. [BIBCODE 1983MNRAS.203..403W ]