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2 Spectroscopy

Using the high-resolution Echelle spectrograph UVES (Dekkeret al. 2000) at the VLT, we carried out spectroscopic observations of nine bona fide and candidate brown dwarfs (M6-M8) (ChaH$\alpha $1 to 8 and 12) and three mid-M-type T Tauri stars (B34, CHXR74 and Sz23) in ChaI between March and May 2000. For each object at least two spectra separated by a few weeks have been obtained.

UVES is ideal for high precision measurements of RVs of faint objects. The spectra have been taken using the red arm of the two-armed UVES spectrograph equipped with a mosaic of two CCDs (blue side of red arm: EEV; red side of red arm: MIT-LL). The wavelength coverage is 6600Å to 10400 Å and the spectral resolution $\rm\lambda / \Delta \lambda=40\,000$. The spectra have been taken with a slit of 1 $\hbox{$^{\prime\prime}$ }$ to 1.2 $\hbox{$^{\prime\prime}$ }$ during a seeing of 0.4 $\hbox{$^{\prime\prime}$ }$ to 1.0 $\hbox{$^{\prime\prime}$ }$.

The spectra have been optimally extracted, including bias correction, flat fielding, cosmic ray elimination and sky subtraction using the Echelle package of IRAF[*].


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Copyright ESO 2001