Physical parameters of T dwarfs derived from high-resolution near-infrared spectroscopy

I present a study aimed at determining the effective temperature and surface gravity of a sample of nine T-type field T dwarfs from the comparison of high-resolution near-infrared spectra and synthetic models. The spectra were obtained with NIRSPEC, using ten echelle orders to cover part of the J-band with a resolving power R~20,000.
The AMES-COND cloudless solar metallicity models used here were obtained using the PHOENIX code. The modelled spectra reproduce quite well the observed features for T dwarfs later than T5. Our results support the assumption of a dust free atmosphere for these objects. Nearly all features observed in their spectra are due to water vapor and potasium. The comparison between the spectroscopically derived Teff and log g of our targets and the evolutionary models yield ages below 1 Gyr and masses of 10-25 Jupiter-mass for about half of the target sample.

 

Date: 
20/11/2008 - 13:00
Speaker: 
Carlos del Burgo
Filiation: 
Dublin Institute for Advanced Physics (Dublin, Ireland)


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