Anthony G. A. Brown

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We use absolute trigonometric parallaxes from the Hipparcos Catalogue to determine individual distances to members of the Hyades cluster, from which the 3-dimensional structure of the cluster can be derived. Inertially-referenced proper motions are used to rediscuss distance determinations based on convergent-point analyses. A combination of parallaxes and(More)
Plasma lipase concentrations were determined in Atlantic salmon post smolts at weekly intervals on two farms from late June. On one farm there was a significant increase (P < 0.001) in lipase concentration which coincided with a suspicion of pancreas disease on clinical grounds. A definitive diagnosis was subsequently confirmed by histopathology. The(More)
A comprehensive census of the stellar content of the OB associations within 1 kpc from the Sun is presented, based on Hipparcos positions, proper motions, and parallaxes. It is a key part of a long-term project to study the formation, structure, and evolution of nearby young stellar groups and related star-forming regions. OB associations are unbound(More)
We review the current knowledge of the population of 'older' stars in the Orion OB1 association, specifically those in subgroups 1a and 1b. We briefly outline the history of the subject and then continue with a summary of the present state of knowledge of the early-type stars in Orion OB1. New results from the Hipparcos parallaxes and proper motions will be(More)
We present a new procedure for the identification of moving groups. It is a combination of two independent member selection methods. One is a modern implementation of a classical convergent point method for proper motion data. The other objectively identifies moving groups in velocity space using proper motions and parallaxes. We briefly describe both(More)
Key words binaries: general – star clusters – methods: N-body simulations – stars: formation Knowledge of the binary population in stellar groupings provides important information about the outcome of the star forming process in different environments. Binarity is also a key ingredient in stellar population studies and is a prerequisite to calibrate the(More)
We have developed a new procedure to identify moving groups, and have applied it to carry out a census of the nearby OB associations based on Hipparcos parallaxes and proper motions (see de Bruijne et al. and de Zeeuw et al. elsewhere in this volume). Here we present three illustrative cases. For α Persei our method allows us to refine the bright end of the(More)