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Published November 2, 2002 | Published + Accepted Version
Journal Article Open

Direct detection of the companion of χ1 Orionis


We present an H-band image of the companion of χ1 Orionis taken with the Keck adaptive optic system and NIRC 2 camera equipped with a 300 mas-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⊙, M_B = 0.15 ± 0.02 M⊙), and to study stellar evolutionary models at a wide spread of masses. The application of Baraffe et al. ([CITE]) 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.

Additional Information

© 2002 ESO. Article published by EDP Sciences. Received 28 August 2002; Accepted 18 September 2002; Published online 21 October 2002. This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. B.K. wants to thank F. Dufey for help with the algebra. R.N. wishes to acknowledge financial support from the Bundesministerium für Bildung und Forschung through the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) under grant number 50 OR 0003. R.J. wishes to acknowledge support from NASA grant NAG5-11905. Some of the Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and religious significance that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. The authors would like to thank Randy Campbell and David LeMignant for help during the observing nights. We thank the referee, G. Gatewood for the helpful comments.

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Published - aaeh282.pdf

Accepted Version - 0209404.pdf


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August 19, 2023
October 18, 2023