THE MILKY WAY GALAXY
The study of the main components of our Galaxy (Disks, Halo, Bulge, Clusters) is of the uttermost importance to understand the formation and evolution of external galaxies. It is only in our Galaxy that the properties of the different components can be studied in great detail.
Observations of the chemical and kinematical properties of samples of stars belonging to halo and thick disk, the discovery of extremely metal poor stars, the detailed study of Globular clusters, allow to define the properties of the oldest galactic populations and the different merging and accretion processes that affected our Galaxy during its evolution. This include the derivation of accurate age and metallicity for stars and globular clusters and the study of the role of stellar internal mixing from anomalous chemical compositions. The discovery of multiple populations in Globular Clusters represents a key ingredient fot the definition of their formation and evolution.
The Galactic Bulge has been studied by dedicated observational projects, aiming to derive the age distribution and metallicity of its stars. Other research activities are dedicated to the global morphology of the Milky Way from stellar counts and on the study of the extinctions on different lines of sight, to constrain the dust properties in our galaxy.
Population synthesis method allows to define the large scale properties of the Galactic stellar populations, from color-magnitude diagrams and from kinematic data. The stars distribution on the CMD carries the signature of the Star Formation History; their position and kinematics trace the dynamical evolution. This information is combined in a simulator, used as a tool to recover the structure and evolution of the Milky Way.
Simulations of stellar counts in any position of the sky can be obtained interactively with the tTRILEGALool at OAPd. The simulator, which includes a wide variety of photometric systems, can be used both to interpret existing data sets, and to design future surveys. In fact, it is being applied to the data from the SDSS-III Survey, in which the OAPd is involved.
A more sophisticated version of the Padova Galaxy Model including the kinematics of the disks and the halo is also developed.
The ESA cornerstone mission Gaia (launch 2013) will allow an unprecedented view of the formation and evolution of our Galaxy, giving the phase space distribution and metallicity for a billion stars. Padova has a important management responsibilities on the DPAC, the international consortium of over 400 scientists that will process the Gaia data. Padova contribution is mainly focused on the problem of deriving the stellar astrophysical parameters that will be part of the final Gaia catalog.
Gaia has limited spectroscopic capabilities, allowing the derivation of chemical abundances and radial velocities only for bright start ( G< 11 e G< 16 respectively). To complement Gaia measures, a 300-author team proposed the Gaia-ESO Public Spectroscopic Survey to ESO and was granted of 300 nights. The survey will derive metallicity and radial velocities up to G=19, for field stars and for open clusters, using FLAMES (GIRAFFE and UVES) on the VLT, to obstain an homogeneous study of all Galactic stellar populations. Padova Observatory is one of the leading Institutes in this project (with Firenze and Bologna).
The OAPd is involved in the RAVE survey, that secured spectra of bright high galactic latitude stars in the same wavelength region studied with GAIA. The main objective of the survey is to derive radial velocities and chemical abundances. Researchers at the Observatory are responsible for the data extraction and calibration, and for the validation of the derived atmospheric parameters via the acquisition and analysis of NTT and AAT data.
A sample of Red Clump Stars from the Hipparcos Catalogue is the target of the ARCS spectroscopic survey, conducted at the Asiago telescope. Coupling the astrometric, kinematic and photometric information will provide important clues for studies of the galactic structure and dynamics. This, and other researches benefit from the development of a library of synthetic stellar spectra covering the wavelength range from 2500 to 10500 A and with various values of the spectral resolution. This library constitutes the reference data base for the automated analysis of spectral surveys.