Séminaire IPAG

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Finding nearby Earth analogues with PLATO and the Terra Hunting Experiment

jeudi 5 décembre 2024 - 11h00

Suzanne Aigrain - University of Oxford
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The new generation of Extreme Precision Radial Velocity (EPRV) instruments have an instrumental precision of order 10cm/s. Whether in standalone “survey” mode, or as part of the follow-up effort for space-based transit surveys TESS and PLATO, they open up the prospect of detecting planets similar to the Earth around nearby, Sun-like stars in the coming decade - paving the way for observations of their atmospheres with future space missions such as HWO or LIFE. However, we must overcome one key obstacle: the intrinsic variability of the host star. Over the last decade, multi-output latent Gaussian Process models (sometimes referred to simply as “multi-GPs”) have emerged as a powerful tool to separate the reflex motion caused by planets from the more complex signatures of stellar activity in the time-domain. I will outline the physical and statistical basis of these models, and illustrate their strengths and weaknesses using practical applications to data from the Sun and from more active stars. These methods are data-hungry, and will benefit enormously from the intensive, long-baseline monitoring foreseen for the Terra Hunting Experiment, which will monitor a few dozen stars every night for a decade. I will show that, given enough high-quality data, we can correct instrumental and activity signals down to the ~m/s level for Sun-like stars, and detect super-Earths in their habitable zone. Nonetheless, further progress is needed to detect true Earth analogues. I will outline some promising lines of enquiry, including building more physically motivated yet computationally efficient activity models, and new insights into the RV variability of the “quiet” solar photosphere.

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Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères