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2.8 Overall Scientific Objectives
Since its conception, the main scientific goal of the GAIA mission was
a better understanding of the structure, formation and evolution of the
Galaxy we live in. During the mission design phase, however, it was
realized that its scientific potential was substantially more far-reaching.
According to the extensive mission preliminary studies, all branches of
astrophysics will greatly benefit from the immense quantity of extremely
accurate data provided by GAIA.
Current understanding of the physics of individual stars will be
revolutionized. Very accurate data covering the whole Hertzsprung-Russell
diagram, from pre-main sequence to stellar death, will be available even
for short-lived stellar evolutionary phases, not only for single stars
but also for large numbers of binary and multiple systems. The spatial
distribution of dark matter within the Galaxy will be determined.
A census of the minor bodies in the Solar System, together with measurements
of the number of planets around stars as a function of spectral type, will
quantify planetary system formation modeling, and optimize the search for
extra-trerrestrial life. A large, well-defined all-sky catalogue of galaxies
and quasars will quantify studies of the structure of the local universe and
of much larger scale structures at high redshift. The stars, galaxies, active
galactic nuclei and quasars mapped by GAIA are the natural complement to
surveys at other wavelengths, from ground-based radio observations to
space-based high-energy measurements. Fundamental physics will benefit from
local metric mapping, which will test general relativity to unprecedented
accuracy. More specifically, the scientific topics that will be addressed
by GAIA include ([Gilmore et al. 1998], [Straizys 1999] and [ESA 2000]):
- Galactic Astrophysics:
origin and history of our Galaxy --
tests of hierarchical structure formation theories --
star formation history --
chemical evolution --
inner bulge-bar dynamics --
disk-halo interactions --
dynamical evolution --
nature of the warp --
star cluster disruption --
dynamics of spiral structure --
distribution of dust --
distribution of dark matter --
detection of tidally disrupted debris --
Galaxy rotation curve --
disk mass profile
- Stellar Astrophyiscs:
in situ luminosity function --
dynamics of star forming regions --
luminosity function for pre-main sequence stars --
detection and categorization of rapid evolutionary phases --
complete and detailed local census down to single brown dwarfs --
identification and dating of oldest halo white dwarfs --
age census --
census of binary and multiple stars --
- Distance Scale and Reference Frame:
parallax calibration of all distance scale indicators --
absolute luminosities of Cepheids --
distance to the Magellanic Clouds --
definition of the local, kinematically non-rotating metric
- Local Group and Beyond:
rotational parallaxes for Local Group galaxies --
kinematical separation of stellar populations --
galaxy orbits and cosmological history --
zero proper motion quasar survey --
cosmological acceleration of the Solar System --
surface photometry of galaxies --
detection of supernovae
- Solar System:
deep and uniform detection of minor planets --
taxonomy and evolution --
inner Trojans --
Kuiper Belt objects --
disruption of Oort Cloud
- Extra-Solar Planetary Systems:
complete local census of large planets to 200-500 pc --
orbital characteristics of several thousand systems
- Fundamental Physics:
to
--
to
--
solar to
--
to
/yr --
constraints on gravitational wave energy for
--
constraints on and
from quasar microlensing
Throughout the history of science, substantial enhancements of the measurement
capabilities have always brought to the discovery of unpredicted phenomena.
GAIA will provide multi-epoch astrometric, photometric and spectroscopic
measurements of objects ranging from solar system objects to quasars,
thus constructing the first all-sky phase-space map of the Galaxy as well as
probing the large-scale structure of the low and high redshift universe.
Further scientific results whose nature and importance cannot be foreseen
are therefore to be expected.
As Galileo wrote, ``if they could have seen what we now see, they would judge
how we judge''.
Next: 3. Scientific Case for
Up: 2. The GAIA Mission
Previous: 2.7 Expected Measurement Capabilities
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Mattia Vaccari
2000-12-05