MOONS offers unique features and versatility for a variety of studies:

  1. 1. Galactic Archaeology

The study of resolved stellar populations of the Milky Way and other Local Group galaxies can provide us with a fossil record of their chemo-dynamical and star-formation histories over many gigayear timescales. Scheduled for launch in 2013, the ESA Gaia mission will deliver new insight into the assembly history of the Milky Way, but to exploit its full potential ground-based follow-up is required.

MOONS will provide this crucial follow-up for Gaia and for other ground based surveys with VISTA, Pan-STARRS, UKIDSS, by measuring accurate radial velocities, metallicities and chemical abundances for several millions of stars.

Given the spectral resolutions (R~9,000 and R~20,000) and the ability of observing in the near-IR, MOONS will perfectly complement the ongoing and planned surveys including the new large Gaia-ESO public spectroscopic survey. The unique features of MOONS will allow us in particular to clarify the nature of the extincted regions of the Bulge, but also to assess the chemo-dynamical structure of the Thin and Thick Disc, understand the importance of satellites and streams in the Halo, ultimately creating an accurate 3D map of our Galaxy to provide essential insight into its origin and evolution.

  1. - Bulge and disc: Near-IR is less sensitive to dust obscuration and combined with collective power of 8.2m VLT can  reach a distance of ~12 kpc, essentially looking through the Bulge and disc. 

- Streams in the Halo  and clusters: Photometrically selected with Gaia, SDSS, Pan-STARRS, VISTA, UKIDSS, LSST etc.

- Resolved stellar population in external galaxies: Magellanic clouds, Nearby galaxies, follow-up of VISTA and UKIDSS

  1. 2. Galaxy evolution

Tracing the assembly history of galaxies over cosmic time remains a primary goal for observational and theoretical studies of the Universe. Even though, in recent years, large spectroscopic surveys at optical wavelengths (0.3m - 1m) have provided key information on the formation and evolution of galaxies, near-IR spectroscopy is now crucial to extend our knowledge beyond z≈1. In fact, at these redshifts almost all the main spectral features are shifted at >1m.  Exploiting the large multiplex and wavelength coverage of MOONS it will be possible to create the equivalent of the successful Sloan Digital Sky Survey, but at z>1. This will provide an unparalled resource to study the physical processes that shape galaxy evolution and determine the key relations between stellar mass, star-formation, metallicity and the role of feedback. Filling a critical gap in discovery space, MOONS will be a powerful instrument to unveil ``the redshift desert” (1.5<z<3) and study this crucial epoch around the peak of star-formation, the assembly of the most massive galaxies, the effect of the environment and the connection with the shining of powerful active nuclei.

An SDSS-like survey at z ≈ 1-1.5

A huge legacy value

Unique, large samples of galaxies at z>1 to achieve robust measurements of inter-dependence of key physical parameters.

- Accurately determine the critical relation between stellar mass, star-formation and metalllicity and the role of feedback.

- Study the crucial effect of the environment

- Unveil the link between mass accretion and central black hole growth

  1. - Determine the Dark Matter halo mass function via galaxy groups as a fundamental test of the Cold Dark Matter paradigm.

  2. - Allow precise clustering measurements and unprecedented estimation of mass and luminosity function at z>1.

3. Synergy with large-area surveys and Euclid

MOONS is the ideal instrument to provide the essential deep spectroscopic follow up of imaging surveys undertaken with facilities in optical and near-IR (VISTA, UKIDSS, VST, Pan-STARRS, Dark Energy Survey, LSST) and facilities operating at other wavelengths (ALMA, Herschel, eRosita, LOFAR, WISE, ASKAP).

MOONS will play also an important role for the recently approved ESA mission Euclid, covering the same spectral range of the space observations and provide uncontaminated and higher resolution spectra of galaxies that will be very useful to independently assess the level and impact of spectral "confusion", as well as to investigate and correct potential biases introduced by slitless spectroscopy (e.g. redshift accuracy, success rate, emission line properties, galaxy types, etc). 

Target-finder for E-ELT and JWST