Wavelength and colour information

R-SCI-290       The payload shall provide high precision photometric time series in the wavelength band of 500 nm to 1000 nm.

R-SCI-L0-70    PLATO shall provide two colour information for the brightest stars (V< 8).

Colour information is useful for planet validation, planetary atmospheres studies, and complementary science. In particular, colour information will allow us to break degeneracies in asteroseismology models of pulsators with a convective core experiencing heat-driven coherent oscillation modes.

Various topics within PLATO Complementary Science benefit greatly from colour information. As an example, having light curves in two instead of one colour not  only improves the modeling of eclipsing binaries, but also allows to determine the degree of the dominant pulsation modes of heat-driven O to F-type pulsators across the HR diagramme and thus perform asteroseismic (and if applicable binary) modelling. In addition, having light curves in two colours allows us to distinguish between pulsational and differential rotational variability, because the dependence of the pulsation signal on wavelength is different from the wavelength dependence of differential rotation or spots. This is particularly valuable for stars in their formation process. Other science cases that require two colours are connected with transient phenomena in cataclysmic variables or neutron-star/black-hole compact binaries.

The bandwidth of the filters shall be chosen wide enough to allow for precise white-light photometry of stars too bright to be accurately observed by the normal cameras.



PLATO – Revealing habitable worlds around solar-like stars
Definition Study Report, ESA-SCI(2017)1, April 2017