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An Adaptive Optics Survey of M8-M9 Stars: Discovery of 4 Very Low mass Binaries With at Least One System Containing a Brown Dwarf Companion

Laird M. Close·Nick Siegler·Dan Potter·Wolfgang Brandner·James Liebert
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Abstract

Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has allowed for the first time direct adaptive optics (AO) guiding on M8-M9 very low mass (VLM) stars. An initial survey of 20 such objects (SpT=M8-M9) discovered 4 binaries. Three of the systems have separations of less than 4.2 AU and similar mass ratios (Delta K<0.8 mag; 0.85 3 AU. This is likely consistent with the 23+/-5% measured for more massive (M0-M6) stars over the same separation range. It appears M8-M9 binaries have a much smaller semi-major axis distribution peak (~4 AU; with no systems wider than 15 AU) compared to M and G stars which have a broad peak at larger \~30 AU separations.

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Laird M. Close, Nick Siegler, Dan Potter, Wolfgang Brandner, James Liebert. 2002-01-23. An Adaptive Optics Survey of M8-M9 Stars: Discovery of 4 Very Low mass Binaries With at Least One System Containing a Brown Dwarf Companion. https://doi.org/10.1086/339795

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