Bibcode
DOI
Siegler, Nick; Close, Laird M.; Cruz, Kelle L.; Martín, Eduardo L.; Reid, I. Neill
Bibliographical reference
The Astrophysical Journal, Volume 621, Issue 2, pp. 1023-1032.
Advertised on:
3
2005
Journal
Citations
91
Refereed citations
87
Description
We present updated results of a high-resolution, magnitude-limited
(Ks<12 mag) imaging survey of nearby low-mass M6.0-M7.5
field stars. The observations were carried out using adaptive optics at
the Gemini North, VLT, Keck II, and Subaru telescopes. Our sample of 36
stars consists predominantly of nearby (<~30 pc) field stars, five of
which we have resolved as binaries. Two of the binary systems, 2MASSI
J0429184-312356 and 2MASSI J1847034+552243, are presented here for the
first time. All five of the discovered binary systems have separations
between 0.08" and 0.53" (2-9 AU) with similar mass ratios (q>0.8,
ΔKs<1 mag). This result supports the hypothesis that
wide (a>20 AU), very low mass (VLM;
Mtot<0.19Msolar) binary systems are rare. The
projected semimajor axis distribution of these systems peak at ~5 AU,
and we report a sensitivity-corrected binary fraction of
9+4-3% for stars with primaries of spectral type
M6.0-M7.5 with separations >~3 AU and mass ratios q>~0.6. Within
these instrumental sensitivities, these results support the overall
trend that both the semimajor axis distribution and binary fraction are
a function of the mass of the primary star and decrease with decreasing
primary mass. These observations provide important constraints for
low-mass binary star formation theories.