Kenyon, Mike

Contact Email: mk@astro.keele.ac.uk
Institute: Keele University
First Coauthor: Rob Jeffries
Institute: Keele University
Presenting Thesis: Yes
Subject Area: Brown Dwarfs & Extrasolar Planets
Waveband: Optical
Technique: Spectroscopy
Presentation: Poster Display
Title: Spectroscopic Brown Dwarf Candidates Around $\sigma$ Orionis
Abstract: We present a spectroscopic survey of the young stellar cluster surrounding $\sigma$ Ori. High resolution ($\sim1$Å FWHM) spectra were obtained of 80 photometric members using the Wide Field Fibre Optic Spectrograph on the WHT. Two wavelength regions were investigated, one covering the 6708Å lithium I absorption line and the other encompassed the sodium I doublet at 8183 and 8195Å. Thirty four objects in the survey were found to definitely contain lithium at undepleted levels, securing their status as young, very low-mass objects. A further sixteen cluster members show some evidence of lithium but with less confidence. For assumed ages of 2-4Myr, the mass range of these objects is 0.03- $0.1M_{\odot}$. We further investigate these objects using their radial velocities, RI and 2MASS infrared photometry.