FInding ExoeaRths: tackling the ChallengEs of stellar activity

Project Information

FIERCE

Grant agreement ID: 101052347

DOI

10.3030/101052347

EC signature date 22 July 2022

Start date 1 October 2022

End date 30 September 2028

Funded under

• European Research Council (ERC)

Total cost

€ 2 458 705,00

EU contribution

€ 2 458 705,00

Coordinated by

CENTRO DE INVESTIGACAO EM ASTRONOMIA E ASTROFISICA DA UNIVERSIDADE DOPORTO ASSOCIACAO
Portugal

Periodic Reporting for period 1 - FIERCE (FInding ExoeaRths: tackling the ChallengEs of stellar activity)

Reporting period: 2022-10-01 to 2025-03-31

Summary of the context and overall objectives of the project

The detection and characterisation of other Earths, planets with the physical conditions to hold liquid water and thus potential life-sustaining environments, is a bold objective of present-day astrophysics. This goal continuously pushes the development of new ground- and space-based instrumentation. However, the quest for other Earths is severely limited by astrophysical “noise” from the host stars, whose signatures distort the spectra that are used to detect and characterise them. Existing methods usually circumvent the problem without a detailed understanding of the individual sources of variability. This is insufficient to reach the required precision levels. To enable the full scientific success of major exoplanet research facilities a new approach is clearly needed.

FIERCE aims at providing the long-needed step forward to tackle these challenges. The ultimate goal is to i) develop novel approaches to identify, model, and correct stellar spurious signals in radial velocity measurements down to 10 cm/s, and ii) obtain a comprehensive understanding of the impact of stellar granulation and activity on the detection of exoplanet atmospheres.

To this end, FIERCE will approach the problem of stellar “noise” from a whole new angle, building a dedicated facility, the Paranal solar Espresso Telescope (PoET - https://poet.iastro.pt). PoET will connect to the state-of-the-art ESPRESSO spectrograph (ESO) and, using the Sun as a proxy, allow to unambiguously identify and understand the sources of relevant variability in solar-type stars.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

To achieve its science goals, FIERCE is organized in 4 work packages:
WP1: Towards the solution, Building PoET
WP2: Mapping the Sun
WP3: Identify and model stellar RV signals
WP4: Stellar physics and the characterisation of exoplanet atmospheres

WP1: design and build a solar telescope that, connected with ESPRESSO spectrograph at ESO (Chile), will allow to obtain disk resolved and disk integrated spectra of the Sun.

The final design of the instrument was defined, including all the interfaces with ESO. The detailed design of the project was delivered to ESO. This process converged towards the signature of the "Hosting Agreement" by ESO's Director General (June 2024). The team started the procurement of major instrument components, including the main telescope and the telescope dome. We expect the telescope dome to be commissioned in April 2025, and the telescope to be installed in June. Scientific observations will start at that moment.

WP2: The main goal is to prepare, plan, and acquire the observations with PoET. Before PoET is ready, preparatory activities have been followed: i) the preparation of the observational software that will interface to the telescope, and ii) the planning of the observations and their sequence.

On the observational software side, requirements are defined and the implementation is ongoing. The team has also prepared a first version of the observation plan following discussions concerning the main science goals of the instrument. Part of this was based on a brainstorming with the international community, done in two different workshops organized in Porto (PoET Workshop #1 and #2, in 2023 and 2024).

WP3 and WP4: These WPs are focused, respectively, on understanding the impact of stellar "noise" in the measurement of precise radial velocities and on the detection of transmission spectroscopy signatures of exoplanets. For this analysis, PoET data will be key. As such, during the first two years of the project the activities were mostly preparatory. In particular, the team hired 5 new PhD students and 3 pos-docs. Different ongoing research projects are focused on the following topics, as already previewed in the application:
- The understanding of individual line variability in the derivation of precise radial velocities;
- The development of the SOAP code, adding new physics and preparing it to ingest PoET data;
- The impact of non-uniformity of the stellar surface in the extraction and interpretation of transmission spectra of exoplanets.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

As per design of the project, we expect that most major results going beyond state-of-the-art will issue from the analysis of PoET data, that will start being gathered after the first light of the instrument (expected June 2025).