REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity
Lead Research Organisation:
University of St Andrews
Department Name: Physics and Astronomy
Abstract
For millennia people have wondered, "Do other Earths exist?" "Are they common?" "Would they show signs of life?". We now have the technical capability to answer these questions. New radial-velocity spectrometers are capable of detecting the reflex motions of stars
hosting Earth-mass planets in their habitable zones; the James Webb Space Telescope has the power to probe the atmospheres of rocky exoplanets. Yet the unprecedented precision of these instruments' measurement capabilities is up against a fundamental astrophysically-imposed barrier to achieving these goals: contamination of exoplanetary signals by stellar activity and variability. Further progress is contingent on solving this "variability problem".
REVEAL gathers world-leading experts in exoplanetary and stellar physics to tackle this problem in synergy:
- We will build on recent advances in magnetohydrodynamic simulations of stellar atmospheres, and data-driven efforts to separate the exoplanet signal from the stellar variability.
- We will simulate the "ground truth" of the turbulent physics of entire stellar photospheres resolved at the level of individual convective cells for a broad class of stars.
- We will model the emergent spectra of these "virtual" stars and "observe" them using the same data-processing pipelines as stellar radial-velocity and transit-spectroscopy observations.
We will continue to observe the Sun and stars hosting small planets found with TESS and PLATO. The stars' own spectra will REVEAL the clues needed to disentangle stellar variability from our measurements of their planets' masses and the fingerprints of molecules in their atmospheres. Our unified efforts will enable the new cutting-edge space observatories and ground-based facilities to realize the full potential of their designs, bringing us closer to the most profound discoveries we could hope to achieve in our lifetimes - the identification of another Earth or even possible signs of life on another planet.
hosting Earth-mass planets in their habitable zones; the James Webb Space Telescope has the power to probe the atmospheres of rocky exoplanets. Yet the unprecedented precision of these instruments' measurement capabilities is up against a fundamental astrophysically-imposed barrier to achieving these goals: contamination of exoplanetary signals by stellar activity and variability. Further progress is contingent on solving this "variability problem".
REVEAL gathers world-leading experts in exoplanetary and stellar physics to tackle this problem in synergy:
- We will build on recent advances in magnetohydrodynamic simulations of stellar atmospheres, and data-driven efforts to separate the exoplanet signal from the stellar variability.
- We will simulate the "ground truth" of the turbulent physics of entire stellar photospheres resolved at the level of individual convective cells for a broad class of stars.
- We will model the emergent spectra of these "virtual" stars and "observe" them using the same data-processing pipelines as stellar radial-velocity and transit-spectroscopy observations.
We will continue to observe the Sun and stars hosting small planets found with TESS and PLATO. The stars' own spectra will REVEAL the clues needed to disentangle stellar variability from our measurements of their planets' masses and the fingerprints of molecules in their atmospheres. Our unified efforts will enable the new cutting-edge space observatories and ground-based facilities to realize the full potential of their designs, bringing us closer to the most profound discoveries we could hope to achieve in our lifetimes - the identification of another Earth or even possible signs of life on another planet.
Organisations
- University of St Andrews (Lead Research Organisation)
- Las Cumbres Observatory (Collaboration)
- Open University (Collaboration)
- University of Leicester (Collaboration)
- University of Bern (Collaboration)
- Queen's University Belfast (Collaboration)
- Keele University (Collaboration)
- European Space Agency (Collaboration)
- National Institute for Astrophysics (Collaboration)
- American River College (Collaboration)
- Harvard University (Collaboration)
- UNIVERSITY OF EDINBURGH (Collaboration)
- University of Geneva (Collaboration)
- MAX-PLANCK-GESELLSCHAFT ZUR FORDERUNG DE (Project Partner)
- Massachusetts Institute of Technology (Project Partner)
- AURA Inc (Project Partner)
Publications
Borsato L
(2024)
Characterisation of the warm-Jupiter TOI-1130 system with CHEOPS and a photo-dynamical approach
in Astronomy & Astrophysics
Bruno G
(2024)
Detailed cool star flare morphology with CHEOPS and TESS
in Astronomy & Astrophysics
Cortés-Zuleta P
(2025)
GI 725A b: A potential super-Earth detected with SOPHIE and SPIRou in an M dwarf binary system at 3.5 pc
in Astronomy & Astrophysics
Egger J
(2024)
Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS
in Astronomy & Astrophysics
Klein B
(2024)
Investigating stellar activity through eight years of Sun-as-a-star observations
in Monthly Notices of the Royal Astronomical Society
Krenn A
(2024)
Characterisation of the TOI-421 planetary system using CHEOPS, TESS, and archival radial velocity data
in Astronomy & Astrophysics
Leleu A
(2024)
Photo-dynamical characterisation of the TOI-178 resonant chain Exploring the robustness of transit-timing variations and radial velocity mass characterisations
in Astronomy & Astrophysics
Mantovan G
(2024)
The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b
in Astronomy & Astrophysics
Nascimbeni V
(2024)
The K2-24 planetary system revisited by CHEOPS
in Astronomy & Astrophysics
Palethorpe L
(2024)
Confronting compositional confusion through the characterisation of the sub-Neptune orbiting HD 77946
in Monthly Notices of the Royal Astronomical Society
| Description | PLATO Stellar Variability Working Group |
| Geographic Reach | Europe |
| Policy Influence Type | Participation in a guidance/advisory committee |
| Title | tweaks2025: A Python Toolkit for Small Exoplanet Analysis |
| Description | The tweaks2025 package is a collection of Jupyter notebooks and Python functions designed for the analysis of small exoplanets using data from TESS, HARPS-N, and CHEOPS. The toolkit facilitates data retrieval from DACE, radial velocity (RV) data processing, stellar activity modeling, and statistical analysis of planetary signals. It is currently in beta testing within my research group and hosted on a private GitHub repository. Future plans include a public release. |
| Type Of Material | Improvements to research infrastructure |
| Year Produced | 2025 |
| Provided To Others? | No |
| Impact | The tweaks2025 package has been deployed to postdocs, graduate students, and final-year dissertation students within my research group, who are using it for exoplanet data analysis. It has improved efficiency in data handling, stellar activity modeling, and planetary signal characterization. Future plans include a public GitHub release, enabling broader adoption by the exoplanet community. |
| Description | CHEOPS |
| Organisation | European Space Agency |
| Country | France |
| Sector | Public |
| PI Contribution | A. Cameron is the ESA-appointed UK member of the Science Team. His responsibilities to the mission include membership of the Preliminary Requirements Review Panel, chairing the panel for scientific validation of the Science Operations Centre, and leading Science Team Working Group B2 for mission Data Analysis. This work continues into the extended mission period 2023-26. |
| Collaborator Contribution | All aspects of mission design, spacecraft and instrument fabrication, and mission software. The project is led by the University of Bern. The University of Geneva hosts the Science Operations Centre. |
| Impact | CHEOPS - CHaracterising ExOPlanet Satellite - is the first mission dedicated to searching for exoplanetary transits by performing ultra-high precision photometry on bright stars already known to host planets. The mission's main science goals are to measure the bulk density of super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterisation studies of exoplanets in these mass and size ranges. Launch is scheduled to take place in November 2019. |
| Start Year | 2012 |
| Description | CHEOPS |
| Organisation | University of Bern |
| Country | Switzerland |
| Sector | Academic/University |
| PI Contribution | A. Cameron is the ESA-appointed UK member of the Science Team. His responsibilities to the mission include membership of the Preliminary Requirements Review Panel, chairing the panel for scientific validation of the Science Operations Centre, and leading Science Team Working Group B2 for mission Data Analysis. This work continues into the extended mission period 2023-26. |
| Collaborator Contribution | All aspects of mission design, spacecraft and instrument fabrication, and mission software. The project is led by the University of Bern. The University of Geneva hosts the Science Operations Centre. |
| Impact | CHEOPS - CHaracterising ExOPlanet Satellite - is the first mission dedicated to searching for exoplanetary transits by performing ultra-high precision photometry on bright stars already known to host planets. The mission's main science goals are to measure the bulk density of super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterisation studies of exoplanets in these mass and size ranges. Launch is scheduled to take place in November 2019. |
| Start Year | 2012 |
| Description | CHEOPS |
| Organisation | University of Geneva |
| Department | Geneva Observatory |
| Country | Switzerland |
| Sector | Academic/University |
| PI Contribution | A. Cameron is the ESA-appointed UK member of the Science Team. His responsibilities to the mission include membership of the Preliminary Requirements Review Panel, chairing the panel for scientific validation of the Science Operations Centre, and leading Science Team Working Group B2 for mission Data Analysis. This work continues into the extended mission period 2023-26. |
| Collaborator Contribution | All aspects of mission design, spacecraft and instrument fabrication, and mission software. The project is led by the University of Bern. The University of Geneva hosts the Science Operations Centre. |
| Impact | CHEOPS - CHaracterising ExOPlanet Satellite - is the first mission dedicated to searching for exoplanetary transits by performing ultra-high precision photometry on bright stars already known to host planets. The mission's main science goals are to measure the bulk density of super-Earths and Neptunes orbiting bright stars and provide suitable targets for future in-depth characterisation studies of exoplanets in these mass and size ranges. Launch is scheduled to take place in November 2019. |
| Start Year | 2012 |
| Description | HARPS-North |
| Organisation | Harvard University |
| Department | Harvard-Smithsonian Center for Astrophysics |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | St Andrews, Belfast and Edinburgh paid for and fabricated the front end optics and control systems of HARPS-N. PDRAs Thomas Wilson and subsequently Pia Cortes Zuleta are developing and testing target validation and ranking procedures for PLATO, by selecting TESS targets for HARPS-N follow-up. |
| Collaborator Contribution | Harvard provided detectors, Geneva led the project and built the spectrograph. In exchange for the instrument, INAF have provided 80N/year of guaranteed observing time on the 3.5-m TNG over 5 years. |
| Impact | The HARPS-N spectrograph is a high-precision radial-velocity instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere and installed at the TNG on La Palma Island (Canary Islands) to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements. To date it has produced 60% of the mass determinations in existence for transiting super-Earth and mini-Neptune planets discovered with the NASA Kepler/K2 mission. Over the subsequent five years (2017-2022) further guaranteed time was awarded by INAF to characterise planets transiting brighter stars from the NASA TESS mission and the Swiss-led ESA CHEOPS satellite following their respective launches in 2018. In the period of the third agreement with INAF (2023-2028) this work continues, working towards RV followup of PLATO targets around the end of the agreement period. |
| Start Year | 2010 |
| Description | HARPS-North |
| Organisation | National Institute for Astrophysics |
| Country | Italy |
| Sector | Academic/University |
| PI Contribution | St Andrews, Belfast and Edinburgh paid for and fabricated the front end optics and control systems of HARPS-N. PDRAs Thomas Wilson and subsequently Pia Cortes Zuleta are developing and testing target validation and ranking procedures for PLATO, by selecting TESS targets for HARPS-N follow-up. |
| Collaborator Contribution | Harvard provided detectors, Geneva led the project and built the spectrograph. In exchange for the instrument, INAF have provided 80N/year of guaranteed observing time on the 3.5-m TNG over 5 years. |
| Impact | The HARPS-N spectrograph is a high-precision radial-velocity instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere and installed at the TNG on La Palma Island (Canary Islands) to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements. To date it has produced 60% of the mass determinations in existence for transiting super-Earth and mini-Neptune planets discovered with the NASA Kepler/K2 mission. Over the subsequent five years (2017-2022) further guaranteed time was awarded by INAF to characterise planets transiting brighter stars from the NASA TESS mission and the Swiss-led ESA CHEOPS satellite following their respective launches in 2018. In the period of the third agreement with INAF (2023-2028) this work continues, working towards RV followup of PLATO targets around the end of the agreement period. |
| Start Year | 2010 |
| Description | HARPS-North |
| Organisation | Queen's University Belfast |
| Department | Astrophysics Research Centre |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | St Andrews, Belfast and Edinburgh paid for and fabricated the front end optics and control systems of HARPS-N. PDRAs Thomas Wilson and subsequently Pia Cortes Zuleta are developing and testing target validation and ranking procedures for PLATO, by selecting TESS targets for HARPS-N follow-up. |
| Collaborator Contribution | Harvard provided detectors, Geneva led the project and built the spectrograph. In exchange for the instrument, INAF have provided 80N/year of guaranteed observing time on the 3.5-m TNG over 5 years. |
| Impact | The HARPS-N spectrograph is a high-precision radial-velocity instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere and installed at the TNG on La Palma Island (Canary Islands) to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements. To date it has produced 60% of the mass determinations in existence for transiting super-Earth and mini-Neptune planets discovered with the NASA Kepler/K2 mission. Over the subsequent five years (2017-2022) further guaranteed time was awarded by INAF to characterise planets transiting brighter stars from the NASA TESS mission and the Swiss-led ESA CHEOPS satellite following their respective launches in 2018. In the period of the third agreement with INAF (2023-2028) this work continues, working towards RV followup of PLATO targets around the end of the agreement period. |
| Start Year | 2010 |
| Description | HARPS-North |
| Organisation | University of Edinburgh |
| Department | Institute for Astronomy |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | St Andrews, Belfast and Edinburgh paid for and fabricated the front end optics and control systems of HARPS-N. PDRAs Thomas Wilson and subsequently Pia Cortes Zuleta are developing and testing target validation and ranking procedures for PLATO, by selecting TESS targets for HARPS-N follow-up. |
| Collaborator Contribution | Harvard provided detectors, Geneva led the project and built the spectrograph. In exchange for the instrument, INAF have provided 80N/year of guaranteed observing time on the 3.5-m TNG over 5 years. |
| Impact | The HARPS-N spectrograph is a high-precision radial-velocity instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere and installed at the TNG on La Palma Island (Canary Islands) to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements. To date it has produced 60% of the mass determinations in existence for transiting super-Earth and mini-Neptune planets discovered with the NASA Kepler/K2 mission. Over the subsequent five years (2017-2022) further guaranteed time was awarded by INAF to characterise planets transiting brighter stars from the NASA TESS mission and the Swiss-led ESA CHEOPS satellite following their respective launches in 2018. In the period of the third agreement with INAF (2023-2028) this work continues, working towards RV followup of PLATO targets around the end of the agreement period. |
| Start Year | 2010 |
| Description | HARPS-North |
| Organisation | University of Geneva |
| Department | Geneva Observatory |
| Country | Switzerland |
| Sector | Academic/University |
| PI Contribution | St Andrews, Belfast and Edinburgh paid for and fabricated the front end optics and control systems of HARPS-N. PDRAs Thomas Wilson and subsequently Pia Cortes Zuleta are developing and testing target validation and ranking procedures for PLATO, by selecting TESS targets for HARPS-N follow-up. |
| Collaborator Contribution | Harvard provided detectors, Geneva led the project and built the spectrograph. In exchange for the instrument, INAF have provided 80N/year of guaranteed observing time on the 3.5-m TNG over 5 years. |
| Impact | The HARPS-N spectrograph is a high-precision radial-velocity instrument, similar to HARPS on the 3.6-m ESO telescope in Chile. It will be located in the Northern hemisphere and installed at the TNG on La Palma Island (Canary Islands) to allow for synergy with the NASA Kepler mission. The main scientific rationale of HARPS-N is the characterization and discovery of terrestrial planets by combining transits and Doppler measurements. To date it has produced 60% of the mass determinations in existence for transiting super-Earth and mini-Neptune planets discovered with the NASA Kepler/K2 mission. Over the subsequent five years (2017-2022) further guaranteed time was awarded by INAF to characterise planets transiting brighter stars from the NASA TESS mission and the Swiss-led ESA CHEOPS satellite following their respective launches in 2018. In the period of the third agreement with INAF (2023-2028) this work continues, working towards RV followup of PLATO targets around the end of the agreement period. |
| Start Year | 2010 |
| Description | TECH-LCOGT |
| Organisation | Las Cumbres Observatory |
| Country | United States |
| Sector | Charity/Non Profit |
| PI Contribution | Capital costs of construction of three of the 1-m telescopes in the LGOGT network (SUPAScopes) were funded by the University of St Andrews through SUPA-II. St Andrews continues to fund the maintenance and operations costs of these telescopes, through a combination of internal and external funding, and sale of telescope time. Andrew Cameron and Keith Horne are members of the TECH key project team, which characterises selected exoplanets by intensively monitoring the transit events using the LCOGT 1m network of telescopes. One of our focuses is on the rare "warm Jupiter" class of planets, for which the LCOGT global network is in a unique position to characterise due to the longitudal coverage of telescopes. Additionally we search for for undiscovered planets via transit timing variations and monitor selected K2 transiting planets that require photometric observations in order to fully characterise the system. |
| Collaborator Contribution | LCOGT built, maintains and operates the telescopes. |
| Impact | 6 publications to date with either Cameron or Horne as co-authors. |
| Start Year | 2009 |
| Description | WASP |
| Organisation | American River College |
| Country | United States |
| Sector | Academic/University |
| PI Contribution | Design and implementation of WASP data-analysis pipeline. Design and implementation of WASP transit-search software. Design and implementation of WASP transit-fitting and orbit-determination software. |
| Collaborator Contribution | QUB: Fabrication, installation and operation of SuperWASP. Keele: Fabrication, installation and operation of WASP-South. Leicester: Design, implementation and maintenance of WASP data archive. |
| Impact | WASP is the most successful of the ground-based searches for transiting exoplanets, having now found nearly 200 planets. The collaboration has produced over 200 refereed publications, and the WASP archive continues to produce new discoveries in the era of NASA's Kepler and TESS missions. |
| Description | WASP |
| Organisation | Keele University |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Design and implementation of WASP data-analysis pipeline. Design and implementation of WASP transit-search software. Design and implementation of WASP transit-fitting and orbit-determination software. |
| Collaborator Contribution | QUB: Fabrication, installation and operation of SuperWASP. Keele: Fabrication, installation and operation of WASP-South. Leicester: Design, implementation and maintenance of WASP data archive. |
| Impact | WASP is the most successful of the ground-based searches for transiting exoplanets, having now found nearly 200 planets. The collaboration has produced over 200 refereed publications, and the WASP archive continues to produce new discoveries in the era of NASA's Kepler and TESS missions. |
| Description | WASP |
| Organisation | Open University |
| Department | School of Physical Sciences |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Design and implementation of WASP data-analysis pipeline. Design and implementation of WASP transit-search software. Design and implementation of WASP transit-fitting and orbit-determination software. |
| Collaborator Contribution | QUB: Fabrication, installation and operation of SuperWASP. Keele: Fabrication, installation and operation of WASP-South. Leicester: Design, implementation and maintenance of WASP data archive. |
| Impact | WASP is the most successful of the ground-based searches for transiting exoplanets, having now found nearly 200 planets. The collaboration has produced over 200 refereed publications, and the WASP archive continues to produce new discoveries in the era of NASA's Kepler and TESS missions. |
| Description | WASP |
| Organisation | University of Leicester |
| Department | Department of Physics & Astronomy |
| Country | United Kingdom |
| Sector | Academic/University |
| PI Contribution | Design and implementation of WASP data-analysis pipeline. Design and implementation of WASP transit-search software. Design and implementation of WASP transit-fitting and orbit-determination software. |
| Collaborator Contribution | QUB: Fabrication, installation and operation of SuperWASP. Keele: Fabrication, installation and operation of WASP-South. Leicester: Design, implementation and maintenance of WASP data archive. |
| Impact | WASP is the most successful of the ground-based searches for transiting exoplanets, having now found nearly 200 planets. The collaboration has produced over 200 refereed publications, and the WASP archive continues to produce new discoveries in the era of NASA's Kepler and TESS missions. |
| Description | Cafe Scientifique, Pitlochry |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Talk to Cafe Scientifique, Pitlochry, 12 Nov 2024: "Do Other Earths Exist?: REVEALing Signatures of Habitable Worlds Hidden by Stellar Activity" |
| Year(s) Of Engagement Activity | 2024 |
| Description | Good morning scotland |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | BBC Radio Scotland "Good morning Scotland" interview 21 Jan 2025 concerning how to observe the evening "planetary parade" of all bright solar system planets in the early weeks of 2025. |
| Year(s) Of Engagement Activity | 2025 |
| Description | REVEAL press release |
| Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
| Part Of Official Scheme? | No |
| Geographic Reach | National |
| Primary Audience | Public/other audiences |
| Results and Impact | Press release announcing funding of REVEAL project. |
| Year(s) Of Engagement Activity | 2023 |
| URL | https://news.st-andrews.ac.uk/archive/are-we-alone-in-the-universe-new-funding-to-reveal-answers/ |
| Description | SIGMA presentation 1 Nov 2024 |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Regional |
| Primary Audience | Other audiences |
| Results and Impact | Invited presentation to SIGMA Astronomical Society, Moray, 1 Nov 2024: "Exploring small planets with TESS, CHEOPS, HAPS-N, JWST and beyond" |
| Year(s) Of Engagement Activity | 2024 |