COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                      Number 2885

                                        Konkoly Observatory
                                        Budapest
                                        24 March 1986

                                        HU ISSN 0374 - 0676



        CURRENT MICROVARIABILITY FOR THE Be STAR Phi PERSEI



  The binary Be star system Phi Persei has been known to exhibit spectrum and
photometric peculiarities, Models of the system have recently been published
by Kitchin (1982) and Poeckert (1979) with the latter invoking a possible
neutron star or helium core from a previously more massive star for the
secondary object. Photometrically, the star has been observed to vary irregularly
in V magnitude from 4.03 - 4.11 in a manner connected with shell ejection 
from the primary's equator. The Second Supplement to the General Catalogue
of Variable Stars also gives an approximate period for the variation of 19.5
days, a period seemingly unrelated to the orbital period of nearly 127 days.
Other investigators (e.g., Dapergolas et al. 1981) have found general 
irregularity unrelated to this suggested period.
  Phi Persei was observed on 35 nights from September, 1984 to November, 1985
with the 0.6-m telescope and automated photon-counting photometer (with its
uncooled EMI 9924A photomultiplier tube) of the Corralitos Observatory in an
effort to examine the suspected 19.5 day variability. Differential BV photometry
was done utilizing two comparison stars, 2 Persei and HR 538. Unfortunately,
one of these stars (2 Persei) may be variable over the long term as evidenced
by published magnitudes in the literature ranging from V= 5.79 (Nicolet, 1978
and Bright Star Catalogue) to 5.70 (Rufener, 1976 and 1981). The most recent
values of V= 5.70 and B-V= -0.07 were adopted for 2 Persei. Rufener (1981)
gives V= 6.26 for HR 538 and a derived value of B-V= +0.04 was found. The
mean DeltaV and Delta(B-V) between the two comparison stars was observed to be 0.560
(in V) and 0.109 (in B-V) magnitudes, in good agreement with the magnitude
values chosen. Average residuals about these means were 0.008 and 0.007
magnitudes respectively. Extinction and transformations to BV magnitudes were
found by observations of standard stars.
  When the differential magnitude of Phi Persei from each of the comparison
stars was examined, no large-scale variations were found. Residuals from the
mean were calculated and compared to those of the comparison stars with the


following results:

V magnitude

                    2 Per - Phi Per    HR 538 - Phi Per     2 Per - HR 538
Mean                    1.702               2.283               -0.560
Av. residual             .015                .018                 .008


B-V magnitude

Mean                   -0.016               0.093               -0.109
Av. Residual             .007                .009                 .007


The sizes of the average residuals from the means in V magnitude for each of
the comparison stars minus Phi Persei are approximately twice that for the
difference between the comparison stars, leading to the conclusion that
variability of only a very low order occurred during the time period Phi Persei
was under observation, with no concurrent color changes. No correlation of
this microvariability with orbital phase was found. A mean value of V= 3.988
and B-V= -0.054 for Phi Persei for 1984-5 was found.
  Special thanks are rendered to B. Goodrich for automation of the 
photometric system.



                           E.M. HALBEDEL
                           
                           Corralitos Observatory
                           P.O. Box 16314
                           Las Cruces, NM 88004
                           U.S.A.




References:

Dapergolas, A., DiCola, G., Guarnieri, A., and Madama, G., 1981, 
  Inf. Bull. Var. Stars, No. 1920.
Kitchin, C.R., 1982, Mon. Not. Roy. Astr. Soc., 198, 457. [BIBCODE 1982MNRAS.198..457K ]
Nicolet, B., 1978, Astron. Astrophys. Suppl. Ser., 34, 1. [BIBCODE 1978A&AS...34....1N ]
Poeckert, R., 1979, Astrophys. J., 233, L73. [BIBCODE 1979ApJ...233L..73P ]
Rufener, F., 1976, Astron. Astrophys. Suppl. Ser., 26, 275. [BIBCODE 1976A&AS...26..275R ]
Rufener, F., 1981, Astron. Astrophys. Suppl. Ser., 45, 207. [BIBCODE 1981A&AS...45..207R ]