Theta1_Orionis_E
Theta1 Orionis E
Star in the constellation Orion
θ1 Orionis E (Latinised as Theta1 Orionis E) is a double-lined spectroscopic binary located 4' north of θ1 Orionis A in the Trapezium Cluster. The two components are almost identical pre-main-sequence stars in a close circular orbit, and they show shallow eclipses that produce brightness variations of a few tenths of a magnitude.
Each component of the binary system is slightly under 3 M☉. Although they have a subgiant spectral classification, they are still contracting onto the main sequence and are estimated to be only about 500 million years old.[8] It is estimated that they will reach the main sequence as smaller hotter late-B stars.[7]
The variability was first reported in 1954[2] and confirmed as an eclipsing binary in 2012. It has not been assigned a variable star designation but is listed in the New Catalogue of Suspected Variable Stars.[2]