Dieter Schertl, Yuri Y. Balega,
Thomas Preibisch, Gerd Weigelt
Orbital motion of the massive multiple stars in the
Astronomy and Astrophysics, 402, 267-275 (2003)
We present bispectrum speckle interferometry of
the multiple Orion Trapezium stars theta^1 Ori A, B, and C obtained
with the SAO 6m telescope in Russia over a
period of 5.5 years (epochs 1995 - 2001).
Our diffraction-limited images have a resolution
lambda/D of 42 mas (J-band),
57 mas (H-band) and 76 mas (K-band).
We clearly detect
motion of the companions relative to their primary stars in the systems
theta^1 Ori A1-2 (mean separation rho ~ 220 mas,
change in position angle Delta P.A. = 6degr),
theta^1 Ori B2-3 (rho ~ 205 mas, Delta P.A. = 8degr), and
theta^1 Ori C1-2 (rho ~ 37 mas, Delta P.A. = 18degr).
In our K-band image of theta^1 Ori B we resolve a fourth visual component,
confirming its discovery by Simon et al.~(1999).
We determine the J, H, and K magnitudes of the system components
and estimate the stellar masses of the companions in the HR-diagram.
The companions theta^1 Ori C2 and theta^1 Ori B2 show clear evidence of near-infrared
excess in the color-color diagram. The companions theta^1 Ori A2 and
theta^1 Ori B3 show
much stronger extinction than their primary stars, providing evidence
of the presence of circumstellar material around the companions.
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