Leggett, Sandy

Contact Email: skl@jach.hawaii.edu
Institute: Joint Astronomy Centre Hilo Hawaii
First Coauthor: David Golimowski
Institute: Johns Hopkins University
Research URL:http://jach.hawaii.edu/JACpublic/UKIRT/public/research.html
Subject Area: Brown Dwarfs & Extrasolar Planets
Waveband: Infrared
Technique: Photometry
Presentation: Oral Contribution: Tuesday
Title: Infrared Photometry of late-M, L, and T Dwarfs
Abstract: We present $ZJHKL^{\prime}M^{\prime}$ photometry obtained at the UK Infrared Telescope for 58 late-M, L, and T dwarfs most of which have been spectroscopically classified using near-infrared spectra (see paper by co-investigators Geballe, Knapp & Fan). We obtained Z for 42 dwarfs, JHK for 34, $L^{\prime}$ for 18, and $M^{\prime}$ for two L dwarfs and two T dwarfs. These provide the first accurate $M^{\prime}$ photometry for L and T dwarfs and we find that their K- $M^{\prime}$ colors are much bluer than predicted by published models. K- $L^{\prime}$ increases monotonically through most of M, L, and T, but is degenerate between L6 and T5 and so its usefulness as a temperature indicator is limited. The JHK colors of L dwarfs show significant scatter, indicating that these fluxes are sensitive to variations in photospheric dust properties; however J-K is a good estimator of T dwarf subclass. For 16 dwarfs with known parallaxes we present luminosities and estimate effective temperatures to be: $2200~>~T_{\rm eff}~>~1300$ K for L dwarfs and $1300~>~T_{\rm eff}~>~800$ K for known T dwarfs.