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A.V. Halevin, I.L. Andronov Department of Astronomy, Odessa State University T.G.Shevchenko Park, Odessa 270014 Ukraine E-mail: root@astro.odessa.ua
EX Vul is an eclipsing variable with a period P=16.135486 days which is characterized by brightness variations even in total eclipse V.P.Tsessevich, Studies of variable stars in selected regions of the galactic field, (in Russian), Kiev, Naukova Dumka, 1976). They may be caused by gaseous streams in this Algol-type system.
We have studied the object on ~500 negatives (field QQ Vul) obtained at the Schmidt camera in the Abastumani Astrophysical Observatory by G.N.Kimeridze et al. The runs corresponding to the same phase of the ascending branch show significant cycle--to--cycle variability. A mild secondary minimum occurs at phase 0.5, a weak reflection effect may be also present.
Periodogram analysis by using the program FOUR-1 (I.L.Andronov, Odessa Astron. Publ., 7, 49 (1994)) shows a wave with best fit amplitude ~0.1 mag and an ephemeris
Max HJD = 2447040.6881 + 0.1077256*E.
+- 97 +- 28
Owed to different mechanisms of variability, the object is an interesting target for photoelectric and spectral studies.
