The (radial) velocity of stars - detection and characterisation of exoplanets

by André Silva (Instituto de Astrofísica e Ciência do Espaço (IA), Universidade do Porto)

Wednesday 13 Mar 2024, 14:00 → 15:00 Portugal

Sala de Conferências (Departamento de Física FCTUC)

One of the boldest challenges of present-day astrophysics is to find and characterize other Earths: rocky planets that are capable of sustaining liquid water on their surface over long periods of time. One of the most prolific extra-solar planet (also known as exoplanet) discovery methods is radial velocities (RV). However, the identification of Earth-like planets faces significant challenges due to the small amplitudes of such signals and the difficulties introduced by two factors: i) Earth's atmosphere; and ii) the stellar surface presenting temporal and spatial variability. The level of precision needed to detect Earth-like planets orbiting other suns thus motivated new developments in both instrumentation (e.g. ESPRESSO) and data analysis.
In this seminar, I will start by discussing the methodology behind the s-BART (Silva+2022) algorithm and some of its most interesting results. At its core, s-BART is a Bayesian implementation of the widely used template-matching algorithm, extracting RVs through a comparison of stellar spectra with a stellar model. The second part of this talk will focus on a solar telescope -- PoET -- that is being constructed in the Institute of Astrophysics, with first light predicted in 2025. PoET will connect to the "planet hunter" ESPRESSO spectrograph (ESO-VLT), allowing us to acquire both disk resolved and disk integrated ("sun-as-a-star") observations of the Sun. This unique dataset will cover the full optical domain (380-780 nm) in one single shot and open the door to better understand the impact of stellar activity on stellar spectra