Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

Chapter 10
Scientific rationale
10.1 Background
10.1.1 Key astrophysical questions
The thematic priorities of the other LAOG teams point toward a number of instrumental needs, too large for
an even big laboratory to cope with. For historical reasons and complementarity with other institutes, in the
early 90’s the LAOG has focused its instrumental interest on the capability to study compact sources : environment
of stars, especially young ones, (FOST) or AGN (SHERPAS) mainly, but also micro-quasars (SHERPAS)
or embedded protostars (ASTROMOL). Recently, with the advent of improved observational techniques (e.g.
high contrast imaging with adaptive optics) that already let to spectacular results in the field, the LAOG has
put forward the case of extra-solar planets.
Studying the nearby environment of young stars with emphasis on extra-solar planetary systems calls first for
imaging capabilities with spectral resolution and high angular resolution. Further progress will come from improving
i) the achievable contrast ii) the imaging capabilities (e.g. measurement of interferometric phase) iii)
the angular resolution.
As a result, based on the instrumental expertise acquired in LAOG for more than 10 years, we have focused our
developments on optical instrumentation dedicated to making progress in these directions. In parallel, some
of us are or should be involved in other instrumental operations also related to studies of extra-solar planets,
planetary formation or stellar formation (astrometry, high spectral resolution, radial velocity spectroscopy...)
but that are outside our main instrumental objectives.
10.1.2 Related instrumental evolution
More specifically, two instrumental fields are currently evolving in the right direction to this end :
• In adaptive optics (AO) imaging, continuing system and sub-systems developments are being done on
major aspects : components (among which deformable micro-mirrors), fast low-cost computers, optimization
modes (such as high contrast AO, or extreme AO (XAO), multi-conjugate AO), laser guide star for
wavefront sensing in empty fields. . .
Part of this progress is essential to our scientific goals, especially deformable mirrors with large actuators
number and the XAO approach.
• Optical multi-telescope interferometry has also evolved a lot in a few years with major equipments (such
as VLTI) now offered to the general User. Further improvement is to come from spectacular progress
in R&D on guided optics, especially integrated optics, with the prospect that much of the present-day
components of an instrument be accommodated within one or a few stable and very small integrated
optics components.
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