Nuno C. Santos
IA / CAUP

Abstract
The detection and characterization of Earth-like planets—those with physical conditions suitable for liquid water and potentially life-sustaining environments—is a major goal of modern astrophysics. However, this search is significantly hindered by astrophysical "noise" from host stars, which distorts the spectra used to detect and analyze these planets. Current methods to mitigate this issue have not yet achieved the necessary level of precision.
The Paranal solar ESPRESSO Telescope (PoET) is a new observing facility designed to address this critical problem. 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. The science of PoET will provide valuable information for the analysis of data from future projects and space missions aiming at the detection and characterization of other Earths. PoET spectra will further allow to tackle other problems in solar and stellar physics.

2026 June 12, 13:30

IA/U.Porto
Centro de Astrofísica da Universidade do Porto (Auditorium)
Rua das Estrelas, 4150-762 Porto