The brown dwarf kinematics project. II. Details on nine wide common proper motion very low mass companions to nearby stars
Abstract
We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for both stellar primaries and low-mass secondaries and masses for the secondaries are inferred using evolutionary models. Of our three new discoveries, the M3+T6.5 pair G 204-39 and SDSS J1758+4633 has an age constrained to 0.5-1.5 Gyr making the secondary a potentially useful brown dwarf benchmark. The G5+L4 pair G 200-28 and SDSS J1416+5006 has a projected separation of ~25,000 AU making it one of the widest and lowest binding energy systems known to date. The system containing NLTT 2274 and SDSS J0041+1341 is an older M4+L0 (>4.5 Gyr) pair which shows Hα activity in the secondary but not the primary making it a useful tracer of age/mass/activity trends. Two of the nine systems have discrepant component ages that emerge from stellar or ultracool diagnostics indicating possible shortcomings in our understanding of the age diagnostics of stars and brown dwarfs. We find a resolved binary frequency for widely separated (>100 AU) low-mass companions (i.e., at least a triple system) which is at least twice the frequency found for the field ultracool dwarf population. The ratio of triples to binaries and quadruples to binaries is also high for this sample: 3:5 and 1:4, respectively, compared to 8 pc sample values of 1:4 and 1:26. The additional components in these wide companion systems indicates a formation mechanism that requires a third or fourth component to maintain gravitational stability or facilitate the exchange of angular momentum. The binding energies for the nine multiples discussed in this text are among the lowest known for wide low-mass systems, suggesting that weakly bound, low-to-intermediate mass (0.2 M_☉ < M_(tot)< 1.0 M_☉) multiples can form and survive to exist in the field (1-8 Gyr).
Additional Information
© 2010 The American Astronomical Society. Received 2009 May 20; accepted 2009 October 26; published 2009 December 10. The authors thank S. Lepine and C. P. McNally for useful conversations about companion systems, E. Mamajek for a useful discussion on supercluster membership as well as a thorough and helpful referee report, and T. Dupuy for a helpful exchange on known UCD companions. Research has benefited from the M, L, and T dwarf compendium housed at DwarfArchives.org and maintained by Chris Gelino, Davy Kirkpatrick, and Adam Burgasser; this publication has made use of the VLM Binaries Archive maintained by Nick Siegler at http://www.vlmbinaries.org and the SPEX Prism Spectral Libraries, maintained by Adam Burgasser at http://www.browndwarfs.org/spexprism. This publication makes use of data products from the Two Micron All-Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/ California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We acknowledge receipt of observation time through the SMARTS consortium.We also thankSMARTS queue observers M. Hernandez and J. Velazquez.Attached Files
Published - Faherty2010p6773Astron_J.pdf
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- Eprint ID
- 17832
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- CaltechAUTHORS:20100331-143542317
- NASA/JPL/Caltech
- NSF
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2010-04-05Created from EPrint's datestamp field
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2021-11-08Created from EPrint's last_modified field
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- Infrared Processing and Analysis Center (IPAC)