Using the distance to the Orion Nebula as 389 parsecs or 1270 +/- 76 light-years, means that the trig. parallax is 2.571 mas (milliarcsec.)
If the principal stars in the Trapezium are; (based on the relative position of STF 748A at 6.55V magnitude)
Star ....... ". mag Spec Class
STF 748 AB 08.9 7.49 O7 B1V
STF 748 AC 13.1 5.06 O7
STF 748 AD 21.5 6.38 B0.5V
STF 748 AE 04.5 11.1 O7
Then the projected distances in AU and light years between the components from A (Mabs=-1.4 Mass=4.5 Solar Masses) is;
B= 3462 AU (0.055 ly.) Mabs =-1.4; 3.6 Solar Masses
C= 5095 AU (0.081 ly.) Mabs =-2.9; 6.4 Solar Masses
D= 8362 AU (0.132 ly.) Mabs =-1.6; 4.7 Solar Masses
E= 1750 AU (0.028 ly.) Mabs =+3.2; 1.5 Solar Masses
In physical size, therefore for the Trapezium is about 10,000 AU across.
The largest estimated minimum orbital period of these stars is about 250,000 years. (about 2.5 times that of Alpha Centauri AB to Proxima) This augers well with the fractional movements so far observed with these stars.
You could compare these values with the older ones described in the dated "
Burnham's Celestial Handbook" Vol.2 "Orion" on Theta Orionis.
Note: If value were between 1400 to 1600 light years, these projected separations would be slightly larger.
For more information and perspective read Andrew James' "
Southern Astronomical Delights" on the
History of the Orion Nebula at;
Hope this helps.
NOTE: I have given open permission for this text to be used in an article "New View of Young, High-Mass Binary Star at Heart of Orion" at
Universe Today on this without any accreditation.