Theta¹ Orionis D (θ¹ Orionis D) is a member of the Trapezium

open cluster An open cluster is a type of star cluster made of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way galaxy, and ...

that lies within the

Orion Nebula The Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula situated in the Milky Way, being south of Orion's Belt in the constellation of Orion. It is one of the brightest nebulae and is visible to the naked eye in the nig ...

. It is a B class blue main sequence star with several faint companions. θ¹ Orionis consists of multiple components, primarily the four stars of the Trapezium cluster ( A, B, C, and D) all within one arc-minute of each other. θ² Orionis is a more distant grouping of three main stars plus several fainter companions, 1-2 arc-minutes from θ¹. θ¹ D itself has a faint optical companion 1.4" away and a spectroscopic companion in a 40-day orbit.

Infrared Optical Telescope Array The Infrared Optical Telescope Array (IOTA) was a stellar interferometer array. IOTA began with an agreement in 1988 among five Institutions, the Smithsonian Astrophysical Observatory, Harvard University, the University of Massachusetts Amherst, t ...

observations suggest another companion at 18.6 mas.

References

{{DEFAULTSORT:Theta1 Orionis D Orionis, Theta1, D Orionis, 41, D Orion (constellation) B-type main-sequence stars 037023

1896 Events January–March * January 2 – The Jameson Raid comes to an end, as Jameson surrenders to the Boers. * January 4 – Utah is admitted as the 45th U.S. state. * January 5 – An Austrian newspaper reports that Wil ...

026224 Durchmusterung objects