Claim: Eta Orionis is a multiple star that is assigned to the oldest and closest part of the association, OB1a which is  a group of massive stars that includes most of the bright stars of Ursa Major.
Evidence: Eta Orionis (η Orionis) is a multiple star in the constellation Orion. It lies at a distance of around 1,000 light years from Earth and is part of the Orion OB1 association. The Orion OB1 stellar association is a contingent group of several dozen hot giant stars of spectral types O and B. It is part of the larger Orion Molecular Cloud Complex.