Title of programme: Probing the starspots of WASP-85 A
Abstract: Transiting planets offer a unique opportunity to probe and spatially resolve the surfaces of distant stars. In turn, this can also feedback into improvements for the confirmation and characterisation of exoplanets. Our aim is to use CHEOPS photometry and spectroscopic observations of WASP-85 A b to isolate and analyse the first cross-correlation functions (CCFs) of starspots on a star other than the Sun. This is possible through the reloaded RM technique, which requires a high precision light curve to accurately normalise the ground-based spectra; in doing so, we can directly subtract in- from out-of-transit observations to isolate the starlight behind the planet. CHEOPS light curves will also serve as a critical tool to robustly identify when the planet occults an active region. WASP-85 A is ideal as its hot Jupiter regularly occults starspots, and it can be observed simultaneously by CHEOPS and HARPS-N. WASP-85 A’s relatively high effective temperature, whilst maintaining a convective envelope, means the net convective blueshift and limb-dependent variations should be large and readily detectable. In a starspot, the convective blueshift is suppressed and the shape of the local CCF altered; characterising these differences is critical to validate stellar models. This proposal is timely as current/next-gen spectrographs urgently need improved stellar characterisation to push forward planet confirmation and characterisation.
Temporal Coverage
2021-04-17T20:48:59Z / 2021-04-18T06:03:00Z
Version
3.0
Mission Description
CHEOPS (Benz et al., https://doi.org/10.1007/s10686-020-09679-4) is a European Space Agency (ESA) mission in partnership with Switzerland with important contributions to the payload and the ground segment from Austria, Belgium, France, Germany, Hungary, Italy, Portugal, Spain, Sweden and the United Kingdom.
The satellite has a single payload comprising an ultra-high precision photometer covering the 330 - 1100 nm wavelength range in a single photometric band. Observations are made as part of the Guaranteed Time Observing Programme that is formulated by the CHEOPS Science Team, and the Guest Observers Programme through which the Community at large can apply for CHEOPS time.
