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Discovery of a Tight Brown Dwarf Companion to the Low Mass Star LHS 2397a

Published online by Cambridge University Press:  26 May 2016

Melanie Freed ,
Laird M. Close  and
Nick Siegler
Melanie Freed
Affiliation:
Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson AZ, USA 85721–0065; mfreed@as.arizona.edu
Laird M. Close
Affiliation:
Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson AZ, USA 85721–0065; mfreed@as.arizona.edu
Nick Siegler
Affiliation:
Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson AZ, USA 85721–0065; mfreed@as.arizona.edu

Abstract

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Using the adaptive optics system, Hōkūpa'a, at Gemini-North, we have directly imaged a companion around the UKIRT faint standard M8 star, LHS 2397a (FS 129) at a separation of 2.96 AU. Near-Infrared photometry obtained on the companion has shown it to be an L7.5 brown dwarf and confirmed the spectral type of the primary to be an M8. We also derive a substellar mass of the companion of 0.068M⊙, although masses in the range (0.061 – 0.069) are possible, and the primary mass as 0.090M⊙ (0.089 – 0.094). Reanalysis of archival imaging from HST has confirmed the secondary as a common proper motion object. This binary represents the first clear example of a brown dwarf companion within 4 AU of a low mass star, and should be the first L7.5 to have a dynamical mass. As part of a larger survey of M8-M9 stars, this object may indicate that there is no “brown dwarf desert” around low mass primaries.

Type
Part 6. Searches for Substellar Companions
Information
Symposium - International Astronomical Union , Volume 211: Brown Dwarfs , 2003 , pp. 261 - 264
Copyright
Copyright © Astronomical Society of the Pacific 2001 

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