EPRV Colloquium May 2026 -- Dr. Nuno Santos

Title: Chasing stellar noise with PoET: lessons from the first month of observations Abstract: The Paranal solar ESPRESSO Telescope (PoET) is a new observing facility designed to address the problem of stellar noise in exoplanet research. Connected to the ESPRESSO spectrograph at the ESO Very Large Telescope (VLT), PoET provides, for the first time, the capability to regularly acquire high-resolution spectra of resolved regions of the solar disk using a state-of-the-art exoplanet-hunting spectrograph. In parallel, PoET also enables the acquisition of time series of disk-integrated (“Sun-as-a-star”) observations. The unique PoET+ESPRESSO dataset, obtained in ultra-high-resolution mode (R ~ 200,000), covers the full optical spectrum (380-780 nm) in a single exposure. By using the Sun as a proxy for other solar-type stars, we aim to achieve a better understanding of how different solar features contribute to spectral variability. Owing to its unique capabilities, PoET data will also enable investigations of several outstanding problems in solar and stellar physics. In this seminar, I will present the scientific motivation behind PoET and describe its design. I will then review the development of the project, from its installation at Paranal to first light on 1 April 2026, highlighting some of the technical and operational challenges encountered along the way. Finally, I will discuss the PoET science program and the organisation of the science team. Preliminary results will be presented to illustrate the instrument's scientific potential.