COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3664

                                               Konkoly Observatory
                                               Budapest
                                               23 September 1991

                                               HU ISSN 0374 - 0676


  Z APODIS IS A PULSATING - NOT A CATACLYSMIC - VARIABLE STAR


Z Apodis is described in the Fourth Edition of the GCVS as a cataclysmic
variable of the Z Cam type (UGZ), and possibly an eclipsing binary. In the
earlier third edition it had been described as a long period (L) star. None of
these descriptions appear to be correct.

This star was measured photo-electrically on 57 occasions at Auckland
Observatory using the 50cm Edith Winstone Blackwell telescope and standard UBV
filters, during the period 1975 to 1983. Because it was faint and appeared
relatively uninteresting, observations then ceased.

The light curves and period are similar to a cepheid, although more symmetrical
than normal. When a complete cycle is plotted on the U-B,B-V diagram this
resemblance continues. The large colour changes, compared to the low
amplitude, do not indicate a binary system. The 1975 observations are best
fitted by a period of 18.89 days, which appears to have persisted up to the
beginning of the second data set. The observations of 1977 to 1981 are best
fitted by a longer period of 18.975 days and an epoch of JD 2443239.05.

We are puzzled by its reclassification. There is no photometric evidence of a
hot star in the system. Even allowing for the possibility of substantial
reddening the colours are unusually red for a CV. When more than one
observation was made on a night there was no evidence of variations greater
than +/- 0.03 magnitudes in V. The pulsation period is typical of a giant
star, very rare for CVs. We have not observed any of the normal features of a
CV on Z Apodis.

The observations are shown in Figures 1 and 2. The U-B light curve is very
noisy, but shows no suppression of amplitude indicating a blue companion. We
cannot exclude a red companion star, but there is no evidence for such an
object. The amplitude of variation appears greater in the 1977 - 81 data. Two
observations in 1983 appear as crosses. The amplitude or the period has
changed again. The period is either erratic, or is changing quickly.
Unfortunately, we have not measured the star since 1983.


                             [FIGURE 1]

         Figure 1   Z APODIS   J.D. 2442422 - 2442623

                             [FIGURE 2]

         Figure 2   Z APODIS   J.D. 2443255 - 2445518



                     BRIAN F. MARINO
                     W.S.G. WALKER
                     Auckland Observatory
                     P.O. Box 18 229, Auckland, 6, N.Z.