Orbital motion of the massive multiple stars in the Orion Trapezium

¹ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
² Special Astrophysical Observatory, Nizhnij Arkhyz, Zelenchuk region, Karachai-Cherkesia, 357147, Russia

Corresponding author: Th. Preibisch, preib@mpifr-bonn.mpg.de

Received: 12 August 2002
Accepted: 6 February 2003

Abstract

We present bispectrum speckle interferometry of the multiple Orion Trapezium stars  A,  B, and  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 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  A1–2 (mean separation mas, change in position angle ),  B2–3 ( mas, ), and  C1–2 ( mas, ). In our K-band image of  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  C2 and  B2 show clear evidence of near-infrared excess in the color-color diagram. The companions  A2 and  B3 show much stronger extinction than their primary stars, providing evidence of the presence of circumstellar material around the companions.