We present below an ongoing project for a new bright time instrument,
a cross-dispersed échelle spectrograph/spectropolarimeter called
ESPaDOnS, for general community use at the Canada-France-Hawaii
Telescope (CFHT). The design
specifications for this instrument are that it is to be able to obtain
a complete optical spectrum (i.e. from 370 to 900 nm) in a single
exposure, with a resolving power of about 50,000. If desired,
ESPaDOnS will be able to measure all the polarisation components of
the stellar light (circular and linear) with the same resolving power.
The spectrograph will be bench-mounted and
fed by a double optical fibre from a Cassegrain module containing all
calibration facilities and the optional polarisation analyser, making it
possible to have extremely good wavelength stability and minimal instrumental
ESPaDOnS should be a unique instrument worldwide in polarimetric mode, competitive with similar instruments on 8 m class telescopes in non-polarimetric mode. With this facility, French and Canadian astronomers should be able to address with unprecedented detail a broad range of important issues in stellar physics, from studies of stellar interiors, to investigations of stellar atmospheres, stellar surfaces, stellar magnetic fields, and to observations of circumstellar environments and extrasolar planets.