Theta Orionis

Theta Orionis (tet Ori, Theta Ori, θ Orionis, θ Ori) is the name of several astronomical objects, located at RA 05^h 35.3^m DEC −05° 24′ :

• θ¹ Orionis, the Trapezium Cluster, an open star cluster, the Orion OB Association 1d
  • θ¹ Orionis A (41 Orionis A, HD 37020, V1016 Orionis), a trinary star system
    • θ¹ Orionis A1 (41 Orionis AA, HD 37020 A)
    • θ¹ Orionis A2 (41 Orionis AB, HD 37020 B)
    • θ¹ Orionis A3 (41 Orionis AC, HD 37020 C)
  • θ¹ Orionis B (41 Orionis B, HD 37021), a quintet star system
    • θ¹ Orionis B1 (41 Orionis BA, HD 37021 A)
    • θ¹ Orionis B2 (41 Orionis BB, HD 37021 B)
    • θ¹ Orionis B3 (41 Orionis BC, HD 37021 C)
    • θ¹ Orionis B4 (41 Orionis BD, HD 37021 D)
    • θ¹ Orionis B5 (41 Orionis BE, HD 37021 E)
    • θ¹ Orionis B West (COUP 766, MAX 97), an astronomical X-ray source
    • θ¹ Orionis B East (COUP 778, MAX 101), an astronomical X-ray source
  • θ¹ Orionis C (41 Orionis C, HD 37022), a binary star system
    • θ¹ Orionis C1 (41 Orionis CA, HD 37022 A)
    • θ¹ Orionis C2 (41 Orionis CB, HD 37022 B)
  • θ¹ Orionis D (41 Orionis D, HD 37023), a B0.5Vp variable star
  • θ¹ Orionis E (COUP 732), a spectroscopic binary star system
  • θ¹ Orionis F, a B8 variable star
  • θ¹ Orionis G (COUP 826, MAX 116), a young stellar object
  • θ¹ Orionis H (COUP 746, MAX 87), a young stellar object
• θ² Orionis (43 Orionis)
  • θ² Orionis A (43 Orionis A, HD 37041), a spectroscopic trinary
    • θ² Orionis A1 (43 Orionis AA, HD 37041 A)
    • θ² Orionis A2 (43 Orionis AB, HD 37041 B)
    • θ² Orionis A3 (43 Orionis AC, HD 37041 C)
  • θ² Orionis B (43 Orionis B, HD 37042), a B1V variable star
  • θ² Orionis C (V361 Orionis, HD 37062), a binary star system
    • θ² Orionis C1 (V361 Orionis A, HD 37062 A)
    • θ² Orionis C2 (V361 Orionis B, HD 37062 B)

The θ Orionis set of objects are located within the NGC 1977 nebula.