Café com Física

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

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

Sala de Conferências (Departamento de Física FCTUC)

Sala de Conferências

Departamento de Física FCTUC

Universidade de Coimbra

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

Organized by

Paulo Brás, Paulo Silva, Jaime Silva