MOONS: the Multi-Object Optical and Near-infrared Spectrograph for the VLT

摘要

MOONS (the Multi-Object Optical and Near-infrared Spectrograph) has been selected by ESO as a third-generation instrument for the Very Large Telescope (VLT). The light grasp of the large collecting area offered by the VLT (8.2m diameter), combined with the large multiplex and wavelength coverage (optical to near-IR: 0.8 - 1.8μm) of MOONS will provide the European astronomical community with a powerful, unique instrument able to pioneer a wide range of Galactic, extragalactic and cosmological studies, and it will provide crucial follow-up for major facilities such as Gaia, VISTA, Euclid and LSST. MOONS has the observational power needed to unveil galaxy formation and evolution over the entire history of the Universe, from stars in our Milky Way, through the redshift desert, and up to the epoch of very first galaxies and reionization of the Universe at redshifts of z ＞ 8-9, just a few million years after the Big Bang. From five years of observations MOONS will provide high-quality spectra for ＞3M stars in our Galaxy and the Local Group, and for 1-2M galaxies at z ＞1 (for an SDSS-like survey), promising to revolutionize our understanding of the Universe. The baseline design consists of-1000 fibres, deployable over a field-of-view of～500 arcmin~2, the largest patrol field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8 - 1.8μm with two spectral resolving powers: in the medium-resolution mode (R～4,000-6,000) the entire wavelength range is observed simultaneously, while the high-resolution mode will cover three selected sub-regions simultaneously: one region with R～8,000 near the Ca Ⅱ triplet to measure stellar radial velocities, and two regions at R～20,000 (one in each of the J- and H-bands), for precision measurements of chemical abundances.