Report - School of Physics

C
ESO 1997 Working Group on Extra-Solar Planets
The ESO 1997 Working Group on the Detection of Extra-Solar Planets consisted
of 16 members, and met on four occasions during 1996 and 1997. The assignment
was to ‘advise ESO [...] on how to help designing a competitive strategy in this field
that is predicted to expand dramatically in the next years, and to become one of the
leading fields of astronomy in the next century.’ The 1997 Working Group and its
task were somewhat comparable to the current effort, with the notable difference
that this time the Working Group was asked to provide recommendations to both
ESA and ESO, thereby encompassing both space- and ground-based astronomy.
This appendix looks briefly at the findings and recommendations of their final report,
published on 10 September 1997. This may provide some understanding of why some
recommendations were successfully implemented while others were not, and what
lessons can be learned from the past.
In the introduction of their report the 1997 Working Group states: ‘Only by allocating
a major fraction of time on some of its telescopes and developing new technology
— and doing it now – will ESO fully exploit its potential in this field and be truly competitive.’
They then laid out their plan to achieve this goal. They identified six areas
in which ESO could play a critical role, namely: radial velocity searches, narrowangle
astrometry, microlensing, direct detection, transits and timing of eclipses. The
recommendations, planned timeframe, and status and achievements of each of these
is summarised in Table 10.
Radial Velocity Searches: The main recommendation was to devote a major
fraction of the observing time at the CAT and the 3.6 m to monitor the radial velocities
of about 1000 stars over the next 5–10 years. They called for the development
of a dedicated spectrograph providing an accuray of about 1 m/s. Such a survey was
considered indispensable to provide targets for VLTI which was assumed to become
operational by 2002. They also advocated high-fidelity calibration of the iodine cell
for UVES and the timely development of CRIRES to provide a survey using twilight
observations in order to obtain complimentary information in the IR.
Narrow-Angle Astrometry: The Working Group considered astrometry a very
attractive method for the study of planets because it allows for determination of
orbits and planet masses directly. It was considered complimentary to other search
methods exploring different regions of parameter space. Achieving an accuracy of
about 10 micro-arcsec was considered feasible. Realisation of the technique was
regarded as technically very challenging, requiring knowledge of the length of the
baseline to within 50 µm and the knowledge of the delay between the two stars with
5 nm precision over a 100 m baseline.
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