Studying The Planetary System Of Proxima Centauri With NIRPS

We obtained 420 high-resolution spectra of Proxima, over 159 nights, using the Near Infra Red Planet Searcher (NIRPS).

We derived 149 nightly binned radial velocity measurements with a standard deviation of 1.69 m/s and a median uncertainty of 55 cm/s, and performed a joint analysis combining radial velocities, spectroscopic activity indicators, and ground-based photometry, to model the planetary and stellar signals present in the data, applying multi-dimensional Gaussian process regression to model the activity signals.

We detect the radial velocity signal of Proxima b in the NIRPS data. All planetary characteristics are consistent with those previously derived using visible light spectrographs.

In addition, we find evidence of the presence of the sub-Earth Proxima d in the NIRPS data. When combining the data with the HARPS observations taken simultaneous to NIRPS, we obtain a tentative detection of Proxima d and parameters consistent with those measured with ESPRESSO.

By combining the NIRPS data with simultaneously obtained HARPS observations and archival data, we confirm the existence of Proxima d, and demonstrate that its parameters are stable over time and against change of instrument. We refine the planetary parameters of Proxima b and d, and find inconclusive evidence of the signal attributed to Proxima c (P = 1900 d) being present in the data.

We measure Proxima b and d to have minimum masses of 1.055 ± 0.055 M_e, and 0.260 ± 0.038 M_e, respectively. Our results show that, in the case of Proxima, NIRPS provides more precise radial velocity data than HARPS, and a more significant detection of the planetary signals.

The standard deviation of the residuals of NIRPS after the fit is 80 cm/s, showcasing the potential of NIRPS to measure precise radial velocities in the near-infrared.

Alejandro Suárez Mascareño, Étienne Artigau, Lucile Mignon, Xavier Delfosse, Neil J. Cook, François Bouchy, René Doyon, Jonay I. González Hernández, Thomas Vandal, Izan de Castro Leão, Atanas K. Stefanov, João Faria, Charles Cadieux, Pierrot Lamontagne, Frédérique Baron, Susana C. C. Barros, Björn Benneke, Xavier Bonfils, Marta Bryan, Bruno L. Canto Martins, Ryan Cloutier, Nicolas B. Cowan, Daniel Brito de Freitas, Jose Renan De Medeiros, Elisa Delgado-Mena, Pedro Figueira, Xavier Dumusque, David Ehrenreich, David Lafrenière, Christophe Lovis, Lison Malo, Claudio Melo, Christoph Mordasini, Francesco Pepe, Rafael Rebolo, Jason Rowe, Nuno C. Santos, Damien Ségransan, Stéphane Udry, Diana Valencia, Gregg Wade, Manuel Abreu, José L. A. Aguiar, Khaled Al Moulla, Guillaume Allain, Romain Allart, Tomy Arial, Hugues Auger, Luc Bazinet, Nicolas Blind, David Bohlender, Isabelle Boisse, Anne Boucher, Vincent Bourrier, Sébastien Bovay, Christopher Broeg, Denis Brousseau, Alexandre Cabral, Andres Carmona, Yann Carteret, Zalpha Challita, Bruno Chazelas, João Coelho, Marion Cointepas, Uriel Conod, Eduardo Cristo, Ana Rita Costa Silva, Antoine Darveau-Bernier, Laurie Dauplaise, Jean-Baptiste Delisle, Roseane de Lima Gomes, Thierry Forveille, Yolanda G. C. Frensch, Félix Gracia Témich, Dasaev O. Fontinele, Jonathan Gagné, Frédéric Genest, Ludovic Genolet, João Gomes da Silva, Nolan Grieves, Olivier Hernandez, Melissa J. Hobson, H. Jens Hoeijmakers, Norbert Hubin, Farbod Jahandar, Ray Jayawardhana, Hans-Ulrich Käufl, Dan Kerley, Johann Kolb, Vigneshwaran Krishnamurthy, Benjamin Kung, Alexandrine L’Heureux, Pierre Larue, Henry Leath, Olivia Lim, Gaspare Lo Curto, Allan M. Martins, Jaymie Matthews, Jean-Sébastien Mayer, Yuri S. Messias et al. (41 additional authors not shown)

Comments: 31 pages, 30 figures, 5 tables, beautiful data
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2507.21751 [astro-ph.EP] (or arXiv:2507.21751v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2507.21751
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Journal reference: 2025, A&A, 700, A11
Related DOI:
https://doi.org/10.1051/0004-6361/202553728
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Submission history
From: Alejandro Suárez Mascareño
[v1] Tue, 29 Jul 2025 12:31:53 UTC (9,588 KB)
https://arxiv.org/abs/2507.21751
Astrobiology,