Resumen
θ^1 Ori E was found to be a double-lined spectroscopic binary by Costero et al. (2006). From the analysis of 86 Echelle spectra obtained during three years, in which the systems of both components are separable, we found that the nearly identical spectra are consistent with both stars being early- to mid-G subgiant stars, with strong Li I λ 6708Å absorption and moderate emission Ca II K lines. The latter features are indicative of the pre-main-sequence evolutionary stage of the binary and, hence, of its membership to the Orion Nebula Cluster (ONC). The radial velocitiy curves of both components yield a circular orbit (e < 10^{-3}) for the binary, with a period of 9.8952+/-0.0007 d. The semi-amplitudes of the curves are almost identical (84.4+/-1.0 km s^{-1}) and the systemic velocity is 34.3+/-0.7 km s^{-1}. The latter value is 8.3 km s^{-1} larger, by at least 3σ, than the average radial velocity of the ONC members, and very similar to the transverse velocity (relative to component A in the Trapezium) derived for the star by Allen et al. (2004) and Sánchez et al. (2008). We conclude that the binary is escaping from the cluster in which it was formed.
