Magnetic field of CP stars in the Ori OB1 association. II. HD36540, HD36668, HD36916, HD37058

Abstract

We present the results of magnetic field measurements of four chemically peculiar (CP) stars with helium abundance anomalies which are the members of the Orion stellar association OB1. The stars under study were classified as magnetic by other authors earlier. The present paper contains the results of the extensive study of the stars. Magnetic field measurements allowed us to conclude that HD36540 has a weak field and the longitudinal component B_e does not exceed 500 G. The longitudinal field of HD36668 varies with the period P = 2_.^d 11884 and the amplitude from −2 to +2 kG. The magnetic field of HD36916 has mainly negative polarity and varies within the range from 0 to −1 kG with the period P = 1.d 565238. HD37058 is a magnetic star, the longitudinal field of which varies from −1.2 to +0.8 kG with the period P = 14_.^d 659. The B_e field variability pattern for the stars HD36916 and HD37058 is of a simple harmonic type. The longitudinal field of HD36668 is best described with two combined harmonic functions (“a doublewave”). The variability period of HD36540 is still undetermined. For all the stars from this paper, we measured radial velocities V_r, axial rotation rates v_e sin i, and determined basic parameters of atmospheres (effective temperatures T_eff and gravity acceleration log g). We also estimated masses M, luminosities L, and radii R of the stars.