Zeta$^2$ Coronae Borealis, A Spectroscopic Triple System Including an Asynchronous Close Binary

Using the 1-m telescope at Ritter Observatory, we took 36 observations ofzeta^2 Coronae Borealis with a fiber-fed echelle spectrograph. From theseobservations, zeta^2 CrB was found to be a triple system and a newspectroscopic orbit was calculated. This orbit has two periods, a 1.72357 dayperiod for the inner binary composed of zeta^2 CrB A & B and a 251 day periodfor the outer binary composed of zeta^2 CrB AB & C. The inner binary is adouble-lined spectroscopic binary composed of two B7 V stars. The innerbinary's center of mass (zeta^2 CrB AB) describes a long-period single-linedvariation identified with the outer binary. The inner binary period issignificantly shorter than the 12.5842 day period previously calculated byAbhyankar & Sarma (1966). The inner binary possesses an essentially circularorbit (e = 0.01) while the outer binary has an eccentric orbit (e = 0.48). Fromthe widths of their Si II 6371 A lines, the vsini's were calculated to be 46+/- 7 km s^-1 for zeta^2 CrB A and 7.5 +/- 2 km s^-1 for zeta^2 CrB B. Aszeta^2 CrB A & B have similar masses, their different rotational velocitiesmake this system a sensitive test of synchronization theories.Comment: 12 pages (3 figures & 1 table, included), to be published in the PAS