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Direct Detection of the Companion of Chi 1 Orionis

B. Koenig·K. Fuhrmann·R. Neuhaeuser·D. Charbonneau·R. Jayawardhana
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Abstract

We present an H-band image of the companion of Chi 1 Orionis taken with the Keck adaptive optic system and NIRC2 camera equipped with a 300mas-diameter coronographic mask. The direct detection of this companion star enables us to calculate dynamical masses using only Kepler's laws M_A = 1.01 +/- 0.13 M_Sun, M_B = 0.15 +/- 0.02 M_Sun, and to study stellar evolutionary models at a wide spread of masses. The application of Baraffe et al. (1998) pre-main-sequence models implies an age of 70-130 Myrs. This is in conflict to the age of the primary, a confirmed member of the Ursa Major Cluster with a canonical age of 300 Myrs. As a consequence, either the models at low masses underestimate the age or the Ursa Major Cluster is considerably younger than assumed.

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B. Koenig, K. Fuhrmann, R. Neuhaeuser, D. Charbonneau, R. Jayawardhana. 2002-09-19. Direct Detection of the Companion of Chi 1 Orionis. https://doi.org/10.1051/0004-6361%3A20021377

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