The Southern African Large Telescope (SALT) and the Potential for Galactic Dynamical Studies

Abstract

Over the next 5 years or so, an international consortium lead by South Africa plans to build an 8-10 m class telescope — the Southern African Large Telescope (SALT) — modelled closely on the novel design of the Hobby-Eberly Telescope (HET) in west Texas. These telescopes represent new paradigms in design, at ~ 20% of the cost of conventional telescopes. SALT will be operated as a queue-scheduled telescope and is primarily designed for spectroscopic observations. I review the characteristics of SALT and discuss the major science drivers, which will decide the probable choice of a first-light instrument package, yet to he defined. This will likely include multi-object spectroscopic capability over a wavelength range of at least 400 nm to 1700 nm and with resolving powers of at least R ~ 300 — 20000, using both fibre-fed and imaging spectrographs. The former will include provision for long-slit and integral field unit fibre arrangements. A Fabry-Perot etalon may also be employed to enable 2-D imaging spectroscopy of particular spectral lines. It is possible that the instrument suite eventually chosen for SALT may have extended capabilities, both in wavelength (perhaps 350 nm ≲ A ≲ 2500 nm) and resolution limit (R up to ~ 100000). I review some of the possible science applications of SALT. Studies in the area of galactic dynamics could include dark matter in elliptical galaxies, galaxy formation and evolution, galaxy rotation curves and applications to general surveys (e.g. the HST Medium Deep Survey; XMM).