Blind search for activity-sensitive lines in the near-infrared using HARPS and NIRPS observations of Proxima and Gl 581

Context. Stellar activity variability is one of the main obstacles to the detection of Earth-like planets using the radial velocity (RV) method. Aims. The aim of this work is to measure the effect of activity in the spectra of M dwarfs and detect activity-sensitive lines in the near-infrared (NIR) to help improve exoplanet detection and characterisation and contribute to further stellar activity analysis in the NIR. Methods. We took advantage of the simultaneous observations of HARPS and the newly commissioned NIRPS spectrograph to carry out a blind search of the most activity-sensitive spectral lines in the NIR using NIRPS spectra and known activity indicators in the optical from HARPS as a reference. We analysed the spectra of Proxima (M5.5V) and Gl 581 (M3V), two M dwarfs with different activity levels and internal structures. Spectral lines were identified for both stars and their profiles were fitted using different models. Results. We found hundreds of lines sensitive to activity for both stars; the Proxima spectra were more affected. For Proxima, around 32% of the identified lines can be used to measure the rotation period of the star, while for Gl 581 the numbers drops to 1%. The fraction of lines sensitive to activity increases with increasing line depth for both stars. A list of 17 lines with rotation period detection for both stars is provided. Conclusions. Stellar activity is able to affect a significant number of spectral lines in the NIR, and methods should be developed to mitigate those effects at the spectral level. The line distortions detected here are expected to come mainly from the flux effect due to temperature contrasts between active regions and the quiet photosphere; however, we cannot rule out the possibility that core-emission from chromospheric activity or Zeeman splitting are also affecting some lines. The new line lists presented here can be used to improve the RV extraction and the detection of RV variability due to stellar activity signals, and to help false positive detection and the modelling of activity variability, thereby enhancing exoplanet detection in the NIR.

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Publication Details

Journal
Springer Link (Chiba Institute of Technology)
Published
2025-08-15
DOI
https://doi.org/10.1051/0004-6361/202555013/pdf
Primary Topic
Stellar, planetary, and galactic studies
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article
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article

Blind search for activity-sensitive lines in the near-infrared using HARPS and NIRPS observations of Proxima and Gl 581

J. V. Seidel, Brooke Cowan, Benjamin Küng, Georgia Mraz et al.
Springer Link (Chiba Institute of Technology)
Stellar, planetary, and galactic studies
article

Blind search for activity-sensitive lines in the near-infrared using HARPS and NIRPS observations of Proxima and Gl 581

J. V. Seidel, Brooke Cowan, Benjamin Küng, Georgia Mraz, N. Nari, Caroline Piaulet, L. Mignon, Léna Parc, Lucimara P. Martins, Dhvani Doshi, Vigneshwaran Krishnamurthy, Bruno Chazelas, A. Silber, I. Saviane, Uriel Conod, Hugues Auger, Antoine Darveau-Bernier, Denis Brousseau, Marion Cointepas, Mathieu Ouellet, Frédérique Baron, Jennifer Glover, J. G. De S. Aguiar, Jean-Sébastien Mayer, Dan Kerley, C. Broeg, Valentina Vaulato, Leslie Moranta, Bachar Wehbé, Mykhaylo Plotnykov, Stefan Pelletier, Yann Carteret, S. C. C. Barros, Ryan Nelson Cloutier, J.-B. Delisle, I. C. Leão, Anne-Sophie Poulin-Girard, Guillaume Allain, Sébastien Bovay, Joost P. Wardenier, Farbod Jahandar, Jeremy Cook, Pierrot Lamontagne, Luc Bazinet, Laurie Dauplaise, Vincent Bruniquel, Avidaan Srivastava, Pierre Larue, Pedro Figueira, Tomy Arial, Lina Messamah, Khaled Al Moulla, Stan Metchev, Johann Kolb, Romain Allart, Dany Mounzer, Allan M. Martins, Nicole Gromek, Pedro Branco, Ares Osborn, Ludovic Genolet, Andres Carmona, Anne Boucher, Xavier Bonfils, Olivia Lim, Simon Thibault, Nuno C. Santos, Yolanda G. C. Frensch, Alexandre Cabral, Jonathan Saint-Antoine, Damien Ségransan, Dasaev O. Fontinele, Jaymie Matthews, Jonathan Gagné, François Bouchy, Ray Jayawardhana, Vincent Yariv, Xavier Dumusque, Michael Sordet, Olivier Hernandez, Henry Leath, José Luis Rasilla, Drew Weisserman, David Lafrenière, Xavier Delfosse, Luca Pasquini, Alexandrine L’Heureux, H. Jens Hoeijmakers, Vladimir Reshetov, Ivan Wevers, Isabelle Boisse, Vincent Bourrier, Gregg Wade, Jon Otegi, Eduardo Cristo, Norbert Hubin, Claudio Melo, Manuel Abreu, René Doyon, Alex Segovia, Étienne Artigau, Christoph Mordasini, Rafael Rebolo, Philippe Vallée, Charles Cadieux, Telmo Monteiro, Alejandro Suárez Mascareño, Jonay I. González Hernández, Ana Rita Costa Silva, Hans-Ulrich Käufl, Stéphane Udry, Louise D. Nielsen, Thierry Forveille, Márcio A. Teixeira, Danuta Sosnowska, Gaspare Lo Curto, Justin Lipper, João Coelho, Frédéric Genest, Gérard Zins, Robin Schnell, François Wildi, Nolan Grieves, Peter Sinclair, Roseane de Lima Gomes, João Lucas Carneiro da Silva, Vera M. Passegger, David Bohlender, Atanas K. Stefanov, Francesco Pepe, Christophe Lovis, Jose Renan De Medeiros, Yuri S. Messias, Thomas Vandal, Félix Gracia Témich, Lison Malo, Elisa Delgado-Mena, Mirsad Sarajlic, Björn Benneke, Jason Rowe, Melissa J. Hobson
article en

Abstract

Context. Stellar activity variability is one of the main obstacles to the detection of Earth-like planets using the radial velocity (RV) method. Aims. The aim of this work is to measure the effect of activity in the spectra of M dwarfs and detect activity-sensitive lines in the near-infrared (NIR) to help improve exoplanet detection and characterisation and contribute to further stellar activity analysis in the NIR. Methods. We took advantage of the simultaneous observations of HARPS and the newly commissioned NIRPS spectrograph to carry out a blind search of the most activity-sensitive spectral lines in the NIR using NIRPS spectra and known activity indicators in the optical from HARPS as a reference. We analysed the spectra of Proxima (M5.5V) and Gl 581 (M3V), two M dwarfs with different activity levels and internal structures. Spectral lines were identified for both stars and their profiles were fitted using different models. Results. We found hundreds of lines sensitive to activity for both stars; the Proxima spectra were more affected. For Proxima, around 32% of the identified lines can be used to measure the rotation period of the star, while for Gl 581 the numbers drops to 1%. The fraction of lines sensitive to activity increases with increasing line depth for both stars. A list of 17 lines with rotation period detection for both stars is provided. Conclusions. Stellar activity is able to affect a significant number of spectral lines in the NIR, and methods should be developed to mitigate those effects at the spectral level. The line distortions detected here are expected to come mainly from the flux effect due to temperature contrasts between active regions and the quiet photosphere; however, we cannot rule out the possibility that core-emission from chromospheric activity or Zeeman splitting are also affecting some lines. The new line lists presented here can be used to improve the RV extraction and the detection of RV variability due to stellar activity signals, and to help false positive detection and the modelling of activity variability, thereby enhancing exoplanet detection in the NIR.

Springer Link (Chiba Institute of Technology)
Openalex Percentile: Top 24%
Stellar, planetary, and galactic studies
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