The project "TArget PrioritizAtion routineS for CHEOPS observations"
(TAPAS4CHEOPS) is funded by the Austrian Research Promotion Agency
(FFG) under the ASAP12 scheme and as part of the Austrian contribution
to the CHEOPS mission.
Both exoplanet missions and ground-based facilities revealed the
existence of a great variety of planets, particularly of
intermediate-mass (sub-Neptune, super-Earth) with masses between 2 and
14 MEarth, which present a large spread in density. These
planets are the primary target of CHEOPS, the first S-class ESA
mission, which aim is the detection of shallow transits of low- and
intermediate-mass planets orbiting bright stars. Typical CHEOPS
targets will be systems hosting planets already detected by radial
velocity, for which CHEOPS will search for transits, and systems
hosting planets detected with the transit method by other facilities
(e.g., NGTS and TESS), but for which the measurement of the radius
requires a considerable improvement. Hundreds of possible CHEOPS
targets are foreseen, but the time constrained nature of CHEOPS
observations will not allow to observe them all. It is therefore
necessary to construct a target prioritization strategy.
The primary aim of this project is to produce the currently missign
piece of information to provide a tool for a fast target
prioritisation. We propose to build a method and tool capable of
providing a fast rough planet characterisation, based on theoretical
models, for CHEOPS targets. We recently developed a method that allows
one to provide a first characterisation of the atmosphere of an
intermediate-mass planet provided only its transit radius. The method
allows one also to infer the minimum planetary mass, while the maximum
mass can be inferred from considerations on planetary density and
We are currently computing
a large grid of hydrodynamic models of the upper atmosphere of planets considering a parameter space
composed by: planetary mass, radius, equilibrium temperature, and stellar high-energy input
flux. We will use the grid of models, together with available predictions of the atmospheric masses
to compute planet atmospheric evolution tracks, taking into account a range of realistic levels for
the initial high-energy stellar flux. We will use the grids to design a characterisation scheme for the planets
discovered with the radial velocity method and with transits detected by CHEOPS. The
scheme will be made available through a public web tool and will be used to prioritize either
further CHEOPS observations or follow-up observations aiming at a full atmospheric
characterisation. We will use our developed innovative method to design also a
characterisation scheme for planets discovered with the transit method by other facilities,
hence possible CHEOPS targets. Also these tools will be made available through a public
web site. We will finally explore possible wider implications of our findings to study the
feasibility of a large-scale usage of the tools developed within the project.
Luca Fossati (PI)
Darya Kubyshkina (main project postdoc)
Helmut Lammer (support)
Monika Lendl (support)
Space Research Institute, Austrian Academy of Sciences. Schmiedlstrasse 6, 8042 Graz, Austria.
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