THE MAGNETIC-FIELD AND HELIUM VARIATION OF THE HELIUM-STRONG STAR HD-184927

We have obtained 29 longitudinal magnetic field measurements of the he lium-strong star HD 184927 using the University of Western Ontario pho toelectric polarimeter and the Special Astrophysical Observatory Zeema n Analyzer. These measurements, obtained over similar to 5500 days, co nfirm the presence of a variable line-of-sight magnetic field. A perio d search of these data reveals several acceptable rotational periods, the most significant of which is 9.(d)52961 +/- 0.(d)00731. This perio d is the only one consistent with those determined previously from ana lysis of photometric, equivalent width and magnetic variations (Bond & Levato 1976; Levato & Malaroda 1979). When phased with this period, t he longitudinal field data describe a smooth sinusoidal curve with ext rema of -0.7 kG and +1.8 kG. When we phase the helium equivalent width measurements and u-band photometry of Bond & Levato (1976) with our a dopted period, the maximum of each of these quantities occurs at the s ame phase as the longitudinal field maximum. This indicates that an en hanced patch of helium may exist in the photosphere of HD 184927 near the positive magnetic pole. There is no evidence for such an enhanceme nt near the negative pole. This suggest that significant differences m ay exist in the mag netic field of HD 184927 at the positive and negat ive magnetic poles, consistent with the presence of an important magne tic quadrupole component. By synthesizing C II lambda 6582.9 at a sing le phase, we have attempted, with moderate success, to define the magn etic field geometry. Using the line profile morphology, the observed l ongitudinal field variation, an the position of HD 184927 on the log T -eff - log g diagram (which implies a radius R = 6.6 +/- 0.8 R.), we f ind the projected rotational velocity v(e) sin i 14.5 +/- 2.5 km s(-1) , the inclination of the rotational axis to the line-of-sight i = 25 /- 5 degrees, and the obliquity of the magnetic symmetry axis beta = 7 8 +/- 3 degrees. Possible magnetic configurations range from nearly di polar, to those which contain quadrupole and octupole components compa rable in polar strength to the dipole component.