2003A&A...402..267S

We present bispectrum speckle interferometry of the multiple Orion Trapezium stars θ¹OriA, θ¹OriB, and θ¹OriC 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 λ/D of 42mas (J-band), 57mas (H-band) and 76mas (K-band). We clearly detect motion of the companions relative to their primary stars in the systems θ¹OriA1-2 (mean separation ρ∼220mas, change in position angle ΔPA=6°), θ¹OriB2-3 (ρ∼205mas, ΔPA=8°), and θ¹OriC1-2 (ρ∼37 mas, ΔPA = 18°). In our K-band image of θ¹OriB we resolve a fourth visual component, confirming its discovery by Simon et al. (1999AJ....117.1375S). 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 θ¹OriC2 and θ¹OriB2 show clear evidence of near-infrared excess in the color-color diagram. The companions θ¹OriA2 and θ¹OriB3 show much stronger extinction than their primary stars, providing evidence of the presence of circumstellar material around the companions.