Tracing the young massive high-eccentricity binary system Theta 1 Orionis C through periastron passage - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




Tracing the young massive high-eccentricity binary system Theta 1 Orionis C through periastron passage - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: The nearby high-mass star binary system Theta 1 Orionis C is the brightestand most massive of the Trapezium OB stars at the core of the Orion NebulaCluster, and it represents a perfect laboratory to determine the fundamentalparameters of young hot stars and to constrain the distance of the OrionTrapezium Cluster. Between January 2007 and March 2008, we observed T1OriC withVLTI-AMBER near-infrared H- and K-band long-baseline interferometry, as wellas with bispectrum speckle interferometry with the ESO 3.6m and the BTA 6mtelescopes B- and V-band. Combining AMBER data taken with three different3-telescope array configurations, we reconstructed the first VLTI-AMBERclosure-phase aperture synthesis image, showing the T1OriC system with aresolution of approx. 2 mas. To extract the astrometric data from ourspectrally dispersed AMBER data, we employed a new algorithm, which fits thewavelength-differential visibility and closure phase modulations along the H-and K-band and is insensitive to calibration errors induced, for instance, bychanging atmospheric conditions. Our new astrometric measurements show that thecompanion has nearly completed one orbital revolution since its discovery in1997. The derived orbital elements imply a short-period P=11.3 yrs andhigh-eccentricity orbit e=0.6 with periastron passage around 2002.6. The neworbit is consistent with recently published radial velocity measurements, fromwhich we can also derive the first direct constraints on the mass ratio of thebinary components. We employ various methods to derive the system massM system=44+-7 M sun and the dynamical distance d=410+-20 pc, which is inremarkably good agreement with recently published trigonometric parallaxmeasurements obtained with radio interferometry.



Author: S. Kraus, G. Weigelt, Y.Y. Balega, J.A. Docobo, K.-H. Hofmann, T. Preibisch, D. Schertl, V.S. Tamazian, T. Driebe, K. Ohnaka, R.

Source: https://arxiv.org/







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