Abstract
| - We present bispectrum speckle interferometry of the multiple Orion Trapezium stars $\theta^1{\rm Ori}$ A, $\theta^1{\rm Ori}$ B, and $\theta^1{\rm Ori}$ C obtained with the SAO 6 m 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 $\theta^1{\rm Ori}$ A1-2 (mean separation $\rho\sim 220$ mas, change in position angle $\Delta {\rm PA} = 6\degr$), $\theta^1{\rm Ori}$ B2-3 ( $\rho\sim 205$ mas, $\Delta {\rm PA} = 8\degr$), and $\theta^1{\rm Ori}$ C1-2 ( $\rho\sim 37$ mas, $\Delta {\rm PA} = 18\degr$). In our K-band image of $\theta^1{\rm Ori}$ B we resolve a fourth visual component, confirming its discovery by Simon et al. ([CITE]). 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 $\theta^1{\rm Ori}$ C2 and $\theta^1{\rm Ori}$ B2 show clear evidence of near-infrared excess in the color-color diagram. The companions $\theta^1{\rm Ori}$ A2 and $\theta^1{\rm Ori}$ B3 show much stronger extinction than their primary stars, providing evidence of the presence of circumstellar material around the companions.
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