Europlanet Science Congress 2021
Virtual meeting
13 – 24 September 2021
Europlanet Science Congress 2021
Virtual meeting
13 September – 24 September 2021
EPSC Abstracts
Vol. 15, EPSC2021-810, 2021
European Planetary Science Congress 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Exploring the Nu2 Lupi system with CHEOPS

Laetitia Delrez1,2 and the CHEOPS Consortium*
Laetitia Delrez and the CHEOPS Consortium
  • 1University of Liege, Belgium (
  • 2University of Geneva, Switzerland
  • *A full list of authors appears at the end of the abstract

***Results under embargo. Paper accepted for publication at Nature Astronomy, to be published in June.***

Multi-transiting planetary systems around bright stars offer unique windows to comparative exoplanetology. Nu2 Lupi (HD 136352) is a naked-eye (V=5.8) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6, and 107.6 days via radial velocity monitoring with the HARPS spectrograph. The two inner planets (b and c) were recently found to transit by the TESS mission, prompting us to follow up the system with ESA's brand-new CHaracterizing ExOPlanets Satellite (CHEOPS). This led to the exciting discovery that the outer planet d is also transiting. With its bright Sun-like star, long period, and mild irradiation (∼5.7 times the irradiation of Earth), Nu2 Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. By combining all available space and ground-based data, we measured its radius and mass to be 2.56±0.09 REarth and 8.82±0.94 MEarth, respectively, and refined the properties of all three planets: planet b likely has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the Nu2 Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.

CHEOPS Consortium:

David Ehrenreich, Yann Alibert, Andrea Bonfanti, Luca Borsato, Luca Fossati, Matthew J. Hooton, Sergio Hoyer, Francisco J. Pozuelos, Sebastien Salmon, Sophia Sulis, Thomas G.Wilson, Vardan Adibekyan, Vincent Bourrier, Alexis Brandeker, Sebastien Charnoz, Adrien Deline, Pascal Guterman, Jonas Haldemann, Nathan Hara, Mahmoudreza Oshagh, Sergio G. Sousa, Valerie Van Grootel, Roi Alonso, Guillem Anglada Escude, Tamas Barczy, David Barrado, Susana C. C. Barros, Wolfgang Baumjohann, Mathias Beck, Anja Bekkelien, Willy Benz, Nicolas Billot, Xavier Bonfils, Christopher Broeg, Juan Cabrera, Andrew Collier Cameron, Melvyn B. Davies, Magali Deleuil, Jean-Baptiste Delisle, Olivier D. S. Demangeon, Brice-Olivier Demory, Anders Erikson, Andrea Fortier, Malcolm Fridlund, David Futyan, Davide Gandolfi, Antonio Garcia Munoz, Michael Gillon, Manuel Guedel, Kevin Heng, Laszlo Kiss, Jacques Laskar, Alain Lecavelier des Etangs, Monika Lendl, Christophe Lovis, Pierre F. L. Maxted, Valerio Nascimbeni, Goran Olofsson, Hugh P. Osborn, Isabella Pagano, Enric Palle, Giampaolo Piotto, Don Pollacco, Didier Queloz, Heike Rauer, Roberto Ragazzoni, Ignasi Ribas, Nuno C. Santos, Gaetano Scandariato, Damien Segransan, Attila E. Simon, Alexis M. S. Smith, Manfred Steller, Gyula M. Szabo, Nicolas Thomas, Stephane Udry, and Nicholas A. Walton.

How to cite: Delrez, L. and the CHEOPS Consortium: Exploring the Nu2 Lupi system with CHEOPS, European Planetary Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-810,, 2021.