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Published November 1, 2008 | Published
Journal Article Open

Common proper motion companions to nearby stars : ages and evolution

Abstract

A set of 41 nearby stars (closer than 25 pc) is investigated which have very wide binary and common proper motion (CPM) companions at projected separations between 1000 and 200,000 AU. These companions are identified by astro-metric positions and propermotions from the NOMAD catalog. Based mainly on measures of chromospheric and X-ray activity, age estimation is obtained for most of 85 identified companions. Color-absolute magnitude diagrams are constructed to test whether CPM companions are physically related to the primary nearby stars and have the same age. Our carefully selected sample includes three remote white dwarf companions to main-sequence stars and two systems (55 Cnc and GJ 777A) of multiple planets and distant stellar companions. Ten new CPM companions, including three of extreme separations, are found. Multiple hierarchical systems are abundant; more than 25% of CPM components are spectroscopic or astrometric binaries or multiples themselves. Two new astrometric binaries are discovered among nearby CPM companions, GJ 264 and HIP 59000, and preliminary orbital solutions are presented. The Hyades kinematic group (or stream) is presented broadly in the sample, but we find few possible thick-disk objects and no halo stars. It follows from our investigation that moderately young (age ≾ to Gyr) thin-disk dwarfs are the dominating species in the near CPM systems, in general agreement with the premises of the dynamical survival paradigm.

Additional Information

© 2008 The American Astronomical Society. Received 2008 March 13; accepted 2008 July 1. The research described in this paper was in part carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France; and data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, California Technology Institute, funded by NASA and the National Science Foundation (NSF).

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August 22, 2023
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