Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
Dieter Schertl, Yuri Y. Balega, Thomas Preibisch, Gerd
Weigelt
Orbital motion of the massive multiple stars in
the Orion Trapezium
Astronomy and Astrophysics, 402, 267 (2003)
Abstract.
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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