θ¹ Orionis E (Latinised as Theta¹ Orionis E) is a double-lined

spectroscopic binary A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...

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. Theta1OriELightCurve

Each component of the binary system is slightly under . Although they have a subgiant spectral classification, they are still contracting onto the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

and are estimated to be only about 500 million years old. It is estimated that they will reach the main sequence as smaller hotter late-B stars. The variability was first reported in 1954 and confirmed as an eclipsing binary in 2012. It has not been assigned a

variable star designation In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constell ...

but is listed in the New Catalogue of Suspected Variable Stars.

References

{{DEFAULTSORT:Theta1 Orionis E Orion (constellation) G-type subgiants 5 J05351577-0523100 Orionis, Theta1E Orionis, 41 E