Bispectrum speckle interferometry of the Orion Trapezium stars:
detection of a close (33 mas) companion of Theta1 Ori C
G. Weigelt, Y. Balega, Thomas Preibisch
D. Schertl, M. Schoeller, H. Zinnecker
Astronomy & Astrophysics, 347, L15 (1999)
We present bispectrum speckle interferometry observations
with the SAO 6 m telescope of the four
brightest stars in the Orion Trapezium.
Diffraction-limited images with an unprecedented resolution
lambda/D of 57 mas
and 76 mas were obtained in the H- and K-band, respectively. The H
images of Theta1 Ori C (the star responsible for the
show for the first time that Theta1 Ori C is a close binary
separation of only ~33 mas (H-band observation). The
sub-arcsecond companions of Theta1 Ori A
and Theta1 Ori B reported by Petr et al. (1998) are confirmed.
the magnitudes and colors of the companions to derive information about
their stellar properties from the HR-diagram. In addition we briefly
the multiplicity of the Trapezium stars. Considering both, the visual
the spectroscopic companions of the 4 Trapezium stars, there are at
companions, i.e. at least 1.75 companions per primary on average.
This number is clearly higher than that
found for the low-mass stars in the Orion Nebula cluster as well as in
the field population. This suggests that a different mechanism is at
work in the formation of high-mass multiple systems in the dense
cluster than for low-mass stars.
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