Zeta2 Coronae Borealis, a spectroscopic triple system including an asynchronous close binary.
GORDON K.D. and MULLISS C.L.
Abstract (from CDS):
Using the 1-m telescope at Ritter Observatory, we took 36 observations of ζ2 Coronae Borealis with a fiber-fed echelle spectrograph. From these observations, ζ2 CrB was found to be a triple system and a new spectroscopic orbit was calculated. This orbit has two periods, a 1.72357 day period for the inner binary composed of ζ2 CrB A and B and a 251 day period for the outer binary compsed of ζ2 CrB AB and C. The inner binary is a double-lined spectroscopic binary composed of two B7 V stars. The inner binary`s center of mass (ζ2 CrB AB) describes a long-period single-lined variation identified with the outer binary. The inner binary period is significantly shorter than the 12.5842 day period previously calculated by Abhyankar & Sarma (1966). The inner binary possesses an essentially circular orbit (e = 0.01) while the outer binary has an eccentric orbit (e = 0.48). From the widths of their Si II 6371 Å lines, the υ sin i's were calculated to be 46 ± 7 km.s–1 for ζ2 CrB A and 7.5 ± 2 km.s–1 for ζ2 CrB B. As ζ2 CrB A and B have similar masses, their different rotational velocities make this system a sensitive test of synchronization theories.