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arXiv · 2507.21284

NIRPS detection of delayed atmospheric escape from the warm and misaligned Saturn-mass exoplanet WASP-69b

Romain Allart·Yann Carteret·Vincent Bourrier·Lucile Mignon·Frederique Baron·Charles Cadieux·Andres Carmona·Christophe Lovis·Hritam Chakraborty·Elisa Delgado-Mena·Etienne Artigau·Susana C. C. Barros·Bjorn Benneke·Xavier Bonfils·Francois Bouchy·Marta Bryan·Bruno L. Canto Martins·Ryan Cloutier·Neil J. Cook·Nicolas B. Cowan·Xavier Delfosse·Rene Doyon·Xavier Dumusque·David Ehrenreich·Jonay I. Gonzalez Hernandez·David Lafreniere·Izan de Castro Leao·Lison Malo·Claudio Melo·Christoph Mordasini·Francesco Pepe·Rafael Rebolo·Jose Renan De Medeiros·Jason Rowe·Nuno C. Santos·Damien Segransan·Alejandro Suarez Mascareno·Stephane Udry·Diana Valencia·Gregg Wade·Manuel Abreu·Jose L. A. Aguiar·Babatunde Akinsanmi·Guillaume Allain·Jose Manuel Almenara·Khaled Al Moulla·Tomy Arial·Hugues Auger·Luc Bazinet·Nicolas Blind·Anne Boucher·Christopher Broeg·Denis Brousseau·Alexandre Cabral·Zalpha Challita·Joao Coelho·Marion Cointepas·Ana Rita Costa Silva·Eduardo Cristo·Antoine Darveau-Bernier·Laurie Dauplaise·Roseane de Lima Gomes·Daniel Brito de Freitas·Dasaev O. Fontinele·Thierry Forveille·Yolanda Frensch·Jonathan Gagne·Frederic Genest·Felix Gracia Temich·Nolan Grieves·Olivier Hernandez·Jens Hoeijmakers·Norbert Hubin·Farbod Jahandar·Ray Jayawardhana·Dan Kerley·Johann Kolb·Vigneshwaran Krishnamurthy·Alexandrine L'Heureux·Monika Lendl·Olivia Lim·Gaspare Lo Curto·Jaymie Matthews·Allan M. Martins·Jean-Sebastien Mayer·Stan Metchev·Yuri S. Messias·Leslie Moranta·Dany Mounzer·Nicola Nari·Louise D. Nielsen·Ares Osborn·Lena Parc·Luca Pasquini·Stefan Pelletier·Celine Peroux·Caroline Piaulet·Mykhaylo Plotnykov·Emanuela Pompei·Anne-Sophie Poulin-Girard
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Abstract

Near-infrared high-resolution echelle spectrographs unlock access to fundamental properties of exoplanets, from their atmospheric escape and composition to their orbital architecture, which can all be studied simultaneously from transit observations. We present the first results of the newly commissioned ESO near-infrared spectrograph, NIRPS, from three transits of WASP-69b. We used the RM Revolutions technique to better constrain the orbital architecture of the system. We extracted the high-resolution helium absorption profile to study its spectral shape and temporal variations. Then, we made 3D simulations from the EVE code to fit the helium absorption time series. We measure a slightly misaligned orbit for WASP-69b (psi of 28.7+/-5.7 deg). We confirm the detection of helium with an average excess absorption of 3.17+/-0.05%. The helium absorption is spectrally and temporally resolved, extends to high altitudes and has a strong velocity shift up to -29.5+/-2.5 km/s 50 minutes after egress. EVE simulations put constraints on the mass loss of 2.25 10^11 g/s and hint at reactive chemistry within the cometary-like tail and interaction with the stellar winds that allow the metastable helium to survive longer than expected. Our results suggest that WASP-69b is undergoing a transformative phase in its history, losing mass while evolving on a misaligned orbit. This work shows how combining multiple observational tracers such as orbital architecture, atmospheric escape, and composition, is critical to understand exoplanet demographics and their formation and evolution. We demonstrate that NIRPS can reach precisions similar to HARPS for RM studies, and the high data quality of NIRPS leads to unprecedented atmospheric characterization. The high stability of NIRPS combined with the large GTO available for its consortium, enables in-depth studies of exoplanets as well as large population surveys.

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Romain Allart, Yann Carteret, Vincent Bourrier, Lucile Mignon, Frederique Baron, Charles Cadieux, Andres Carmona, Christophe Lovis, Hritam Chakraborty, Elisa Delgado-Mena, Etienne Artigau, Susana C. C. Barros, Bjorn Benneke, Xavier Bonfils, Francois Bouchy, Marta Bryan, Bruno L. Canto Martins, Ryan Cloutier, Neil J. Cook, Nicolas B. Cowan, Xavier Delfosse, Rene Doyon, Xavier Dumusque, David Ehrenreich, Jonay I. Gonzalez Hernandez, David Lafreniere, Izan de Castro Leao, Lison Malo, Claudio Melo, Christoph Mordasini, Francesco Pepe, Rafael Rebolo, Jose Renan De Medeiros, Jason Rowe, Nuno C. Santos, Damien Segransan, Alejandro Suarez Mascareno, Stephane Udry, Diana Valencia, Gregg Wade, Manuel Abreu, Jose L. A. Aguiar, Babatunde Akinsanmi, Guillaume Allain, Jose Manuel Almenara, Khaled Al Moulla, Tomy Arial, Hugues Auger, Luc Bazinet, Nicolas Blind, Anne Boucher, Christopher Broeg, Denis Brousseau, Alexandre Cabral, Zalpha Challita, Joao Coelho, Marion Cointepas, Ana Rita Costa Silva, Eduardo Cristo, Antoine Darveau-Bernier, Laurie Dauplaise, Roseane de Lima Gomes, Daniel Brito de Freitas, Dasaev O. Fontinele, Thierry Forveille, Yolanda Frensch, Jonathan Gagne, Frederic Genest, Felix Gracia Temich, Nolan Grieves, Olivier Hernandez, Jens Hoeijmakers, Norbert Hubin, Farbod Jahandar, Ray Jayawardhana, Dan Kerley, Johann Kolb, Vigneshwaran Krishnamurthy, Alexandrine L'Heureux, Monika Lendl, Olivia Lim, Gaspare Lo Curto, Jaymie Matthews, Allan M. Martins, Jean-Sebastien Mayer, Stan Metchev, Yuri S. Messias, Leslie Moranta, Dany Mounzer, Nicola Nari, Louise D. Nielsen, Ares Osborn, Lena Parc, Luca Pasquini, Stefan Pelletier, Celine Peroux, Caroline Piaulet, Mykhaylo Plotnykov, Emanuela Pompei, Anne-Sophie Poulin-Girard. 2025-07-28. NIRPS detection of delayed atmospheric escape from the warm and misaligned Saturn-mass exoplanet WASP-69b. https://doi.org/10.1051/0004-6361%2F202452525

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