TOWARD A CONSISTENT MODEL OF THE B0.5IVE-PERSEI(SDO BINARY PHI)

A detailed analysis of a very rich collection of spectroscopic and pho tometric observations of the bright Be star phi Per is presented. Earl ier reports that phi Per is a double-lined spectroscopic binary consis ting of two emission-line objects are confirmed. An orbital solution b ased on the emission-wing radial velocities for both stars has led to a determination of the orbital elements which defines the correct orbi tal phases. All data since the beginning of this century can be reconc iled with a constant orbital period of 126(d).6731 +/- 0(d).0071. The new orbital solution gives lower masses than those found by earlier in vestigators, namely M(1) sin(3) i = 16.35 M(.) and M(2) sin(3) i = 1.6 9 M(.). These masses are in agreement with the recently derived spectr al classes B0.5IVe and sd06: for the primary and secondary, respective ly. Long-term light variations are positively correlated with the emis sion strength, and in the U-B vs. B-V diagram the object has changed i ts apparent photometric type from a B supergiant toward an MS object. Dereddening of the mean seasonal UBV magnitudes from recent years (whe n spectra show the weakest recorded Balmer emission) leads to a photom etric spectral type a bit earlier than B1V. An important and exciting finding is that the emission lines of both stars have been weakening s imultaneously in recent years, which seems to indicate some kind of in teraction between the binary components. The presence of rapid light v ariability is confirmed, but its more detailed analysis is postponed f or another study. Low amplitude orbital light variations with rather c omplicated light and color curves are found after the removal of long- term and rapid changes. The principal maxima and minima of the orbital light curves can be traced in both old and new photometry and can pro bably be attributed to specific circumstellar structures whose signatu res are also seen spectroscopically. Finally, systematic secular chang es in the shape and amplitude of the orbital radial-velocity curve of the Balmer shell lines are found, based on 1024 radial velocities span ning nearly a century.