NIRPS tightens the mass estimate of GJ 3090 b and detects a planet near the stellar rotation period Pierrot Lamontagne, Drew Weisserman, Charles Cadieux, David Lafrenière, Alexandrine L’Heureux, et al. Astronomy and Astrophysics, 2026 We present an updated characterization of the planetary system orbiting the nearby M2 dwarf GJ 3090 (TOI-177; d =22 pc), based on new high-precision radial velocity (RV) observations from NIRPS and HARPS. With an orbital period of 2.85 d, the transiting sub-Neptune GJ 3090 b has a mass we refine to 4.52 ± 0.47 M ⊕ , which, combined with our derived radius of 2.18 ± 0.06 R ⊕ , yields a density of 2.40 −0.30 +0.33 g∉cm −3 . The combined interior structure and atmospheric constraints indicate that GJ 3090 b is a compelling water-world candidate, with a volatile-rich envelope in which water likely represents a significant fraction. We also confirm the presence of a second planet, GJ 3090 c, a sub-Neptune with a 15.9 d orbit and a minimum mass of 10.0 ± 1.3 M ⊕ , which does not transit. Despite its proximity to the star’s 18 d rotation period, our joint analysis using a multidimensional Gaussian process (GP) model that incorporates TESS photometry and differential stellar temperature measurements distinguishes this planetary signal from activity-induced variability. In addition, we place new constraints on a non-transiting planet candidate with a period of 12.7 d, suggested in earlier RV analyses. This candidate remains a compelling target for future monitoring. These results highlight the crucial role of multidimensional GP modelling in disentangling planetary signals from stellar activity, enabling the detection of a planet near the stellar rotation period that could have remained undetected with traditional approaches.
A seeing measurement device for the PoET solar telescope B Wehbe, A Silva, M Abreu, A Cabral, N C Santos, et al. Ras Techniques and Instruments, 2026 Atmospheric seeing arises from stochastic fluctuations in the refractive index of the Earth’s atmosphere, producing random variations in the apparent direction of incoming light from astronomical sources. Scintillation refers to the associated intensity fluctuations induced by these refractive index inhomogeneities. A quantitative relationship between seeing and scintillation was established in 1993, enabling daytime seeing measurements by exploiting the Sun as an extended, bright source and using non-telescopic instrumentation. PoET, the Paranal solar ESPRESSO Telescope, will feed the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, ESPRESSO, at the European Southern Observatory Very Large Telescope. By using the Sun as a proxy for solar-type stars, PoET will facilitate detailed investigations of the physical processes that drive stellar noise in ultra-high-precision radial-velocity measurements for exoplanet studies. The instrument is capable of targeting any region on the solar disc and acquiring spatially resolved spectra over areas ranging from 1 to 55 arcsec. Accurate characterization of daytime atmospheric seeing is therefore essential for selecting the optimal observing aperture and ensuring the scientific performance of PoET. To support this requirement, we have developed and implemented a dedicated solar seeing monitor for daytime deployment at Paranal, Chile, where PoET will operate. In this work, we describe the instrument design and present the results from commissioning and initial on-sky validation.
NIRPS and TESS reveal a peculiar system around the M dwarf TOI-756: A transiting sub-Neptune and a cold eccentric giant Léna Parc, François Bouchy, Neil J. Cook, Nolan Grieves, Étienne Artigau, et al. Astronomy and Astrophysics, 2025 Context. The Near InfraRed Planet Searcher (NIRPS) joined HARPS on the 3.6-m ESO telescope at La Silla Observatory in April 2023, dedicating part of its Guaranteed Time Observations (GTO) program to the radial velocity follow-up of TESS planet candidates to confirm and characterize transiting planets around M dwarfs. Aims. We present the “Sub-Neptunes” subprogram of the NIRPS-GTO, aimed at investigating the composition and formation of sub-Neptunes orbiting M dwarfs. We report the first results of this program with the characterization of the TOI-756 system, which consists of TOI-756 b, a transiting sub-Neptune candidate detected by TESS, as well as TOI-756 c, an additional non-transiting planet discovered by NIRPS and HARPS. Methods. We analyzed TESS and ground-based photometry, high-resolution imaging, and high-precision radial velocities (RVs) from NIRPS and HARPS to characterize the two newly discovered planets orbiting TOI-756, as well as to derive the fundamental properties of the host star. A dedicated approach was employed for the NIRPS RV extraction to mitigate telluric contamination, particularly when the star’s systemic velocity was shown to overlap with the barycentric Earth radial velocity. Results. TOI-756 is a M1V-type star with an effective temperature of Teff ~ 3657 K and a super-solar metallicity ([Fe/H]) of 0.20±0.03 dex. TOI-756 b is a 1.24-day period sub-Neptune with a radius of 2.81 ± 0.10 R⊕ and a mass of 9.8−1.6+1.8 M⊕. TOI-756 c is a cold eccentric (ec = 0.45 ± 0.01) giant planet orbiting with a period of 149.6 days around its star with a minimum mass of 4.05 ± 0.11 MJup. Additionally, a linear trend of 146 m s−1 yr−1 is visible in the radial velocities, hinting at a third component, possibly in the planetary or brown dwarf regime. Conclusions. We present the discovery and characterization of the transiting sub-Neptune TOI-756 b and the non-transiting eccentric cold giant TOI-756 c. This system is unique in the exoplanet landscape, standing as the first confirmed example of such a planetary architecture around an M dwarf. With a density of 2.42 ± 0.49 g cm−3, the inner planet, TOI-756 b, is a volatile-rich sub-Neptune. Assuming a pure H/He envelope, we inferred an atmospheric mass fraction of 0.023 and a core mass fraction of 0.27, which is well constrained by stellar refractory abundances derived from NIRPS spectra. It falls within the still poorly explored radius cliff and at the lower boundary of the Neptune desert, making it a prime target for a future atmospheric characterization with JWST to improve our understanding of this population.
Quantifying thermal water dissociation in the dayside photosphere of WASP-121 b using NIRPS Luc Bazinet, Romain Allart, Björn Benneke, Stefan Pelletier, Joost P. Wardenier, et al. Astronomy and Astrophysics, 2025 The intense stellar irradiation of ultra-hot Jupiters results in some of the most extreme atmospheric environments in the planetary regime. On their daysides, temperatures can be sufficiently high for key atmospheric constituents to thermally dissociate into simpler molecular species and atoms. This dissociation drastically changes the atmospheric opacities and, in turn, critically alters the temperature structure, atmospheric dynamics, and day-night heat transport. To date, however, simultaneous detections of the dissociating species and their thermally dissociation products in exoplanet atmospheres have remained rare. In this work we present the simultaneous detections of H2O and its thermally dissociation product OH on the dayside of the ultra-hot Jupiter WASP-121 b based on high-resolution emission spectroscopy with the recently commissioned Near InfraRed Planet Searcher (NIRPS). We retrieved a photospheric abundance ratio of log10(OH/H2O) = −0.15 ± 0.20, indicating that there is about as much OH as H2O at photospheric pressures, which confirms predictions from chemical equilibrium models. We compared the dissociation on WASP-121 b with other ultra-hot Jupiters and show that a trend in agreement with equilibrium models arises. We also discuss an apparent velocity shift of 4.79−0.97+0.93 km s−1 in the H2O signal, which is not reproduced by current global circulation models. Finally, in addition to H2O and OH, the NIRPS data reveal evidence of Fe and Mg, from which we inferred a Fe/Mg ratio consistent with the solar and host star ratios. Our results demonstrate that NIRPS can be an excellent instrument to obtain simultaneous measurements of refractory and volatile molecular species, thus paving the way for many future studies on the atmospheric composition, chemistry, and the formation history of close-in exoplanets.
A comprehensive study on radial velocity signals using ESPRESSO: Pushing precision to the 10 cm/s level P. Figueira, J. P. Faria, A. M. Silva, A. Castro-González, J. Gomes da Silva, et al. Astronomy and Astrophysics, 2025 Aims. We analyse ESPRESSO data for the stars HD 10700 (τ Ceti), HD 20794 (e Eridani), HD 102365, and HD 304636 acquired via its Guaranteed Time Observations (GTO) programme. We characterise the stars’ radial velocity (RV) signals down to a precision of 10 cm/s on timescales ranging from minutes to planetary periods falling within the host’s habitable zone (HZ). We study the RV signature of pulsation, granulation, and stellar activity, inferring the potential presence of planets around these stars. Thus, we outline the population of planets that while undetectable remain compatible with the available data. Methods. We derived the stellar parameters through different methods for a complete characterisation of the star. We used these parameters to model the effects of stellar pulsations on intra-night RV variations and of stellar activity on nightly averaged values. The RVs were derived both with the cross-correlation method and template matching, as well as over the blue and red ESPRESSO detectors independently to identify colour-dependent parasitic effects of an instrumental or stellar nature. The study of RVs was complemented by an investigation of stellar activity indicators using photospheric information and chromospheric indexes. Results. A simple model of stellar pulsations successfully reproduced the intra-night RV scatter of HD 10700 down to a few cm/s. For HD 102365 and HD 20794, an additional source of scatter at the level of several 10 cm/s remains necessary to explain the data. A kima analysis was used to evaluate the number of planets supported by the nightly averaged time series of each of these three stars, under the assumption that a quasi-periodic Gaussian process (GP) regression is able to model the activity signal. While a frequency analysis of HD 10700 RVs is able to identify a periodic signal at 20 d, when it is modelled along with the activity signal the signal is formally non-significant. Moreover, its physical origin remains uncertain due to the similarity with the first harmonic of the stellar rotation. ESPRESSO data on their own do not provide conclusive evidence to support the existence of planets around HD 10700, HD 102365, or HD 304636. In addition, the comparison of RVs with the contemporaneous indicators displays a strong correlation for HD 102365. The direct interpretation is that half of the RV variance on this star is directly attributed to activity. Conclusions. ESPRESSO is shown to reach an on-sky RV precision of better than 10 cm/s on short timescales (<1h) and of 40 cm/s over 3.5 yr. A subdivision of the datasets showcases a precision reaching 20–30 cm/s over one year. These results impose stringent constraints on the impact of granulation mechanisms on RV. In spite of no detections, our analysis of HD 10700 RVs demonstrates a sensitivity to planets with a mass of 1.7 M⊕ for periods of up to 100 d, and a mass of 2–5 M⊕ for the star’s HZ.
A systematic bias in template-based radial velocity extraction algorithms A. M. Silva, N. C. Santos, J. P. Faria, J. H. C. Martins, E. A. S. Cristo, et al. Astronomy and Astrophysics, 2025 Context. The radial velocity (RV) method plays a key role in modern-day astrophysics. One of the most common techniques for extracting precise RVs from state-of-the-art spectrographs is template-matching (TM) algorithms. They have been shown to perform better than a cross-correlation function (CCF) approach in cases of cooler stars (e.g. M dwarfs) and multiple implementations have appeared over the past years. More recently, line-by-line (LBL) approaches offer an alternative avenue to extract RVs by analyzing individual spectral lines. Aims. In this paper, we identify and explore a previously unidentified, multi-meter-per-second, systematic correlation between time and RVs inferred through TM and LBL methods. We evaluate the influence of the data-driven stellar template in the RV bias and hypothesise on the possible sources of this effect. Methods. We used the s-BART pipeline to extract RVs from three different datasets gathered over four nights of ESPRESSO and HARPS observations. We demonstrate that the effect can be recovered on a larger sample of 19 targets, totalling 4124 ESPRESSO observations over 38 nights. We also showcase the presence of the bias in RVs extracted with the SERVAL and ARVE pipelines. Lastly, we explore the construction of the stellar template over the five years of ESPRESSO observations of HD 10700, totalling more than 2000 observations. Results. We find that a systematic quasi-linear bias affects the RV extraction with slopes that vary from —0.3 ms−1 h−1to —52 m s−1 h−1 in our sample. This trend is not observed in CCF RVs and only appears when all observations of a given star are collected within a short time period (timescales of hours). We show that this systematic contamination exists in the RV time series of two different template-matching pipelines and one line-by-line pipeline, and it is agnostic to the spectrograph. We also find that this effect is linked to the construction of the stellar template, as we were able to mitigate it through a careful selection of the observations used to construct it. Our results suggest that a contamination of micro-telluric features, coupled with other sources of correlated noise, could be the driving factor of this effect. We also show that this effect does not impact the usual usage of template-matching for the detection and characterisation of exoplanets. However, the short-timescale science cases, such as asteroseismology as well as transit and atmospheric characterisation, can be severely affected.
NIRPS detection of delayed atmospheric escape from the warm and misaligned Saturn-mass exoplanet WASP-69 b Romain Allart, Yann Carteret, Vincent Bourrier, Lucile Mignon, Frédérique Baron, et al. Astronomy and Astrophysics, 2025 Context. Near-infrared high-resolution échelle 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. Aims. We present the first results of the newly commissioned ESO near-infrared spectrograph, Near-InfraRed Planet Searcher (NIRPS), from three transits of the well-studied warm Saturn WASP-69b. Our goals are to measure the orbital architecture of the planet through the Rossiter-McLaughlin (RM) effect and its atmospheric escape through the 1083 nm helium triplet. Methods. 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. Results. We measure a slightly misaligned orbit for WASP-69 b (3D spin-orbit angle of 28.7−5.3+6.1 ∘). We confirm the detection of helium with an average excess absorption of 3.17±0.05% (maximum of 4.02%). 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−1 50 minutes after egress. The signature cannot be explained by a thermosphere alone and thus requires 3D modeling of the thermosphere and exosphere. EVE simulations put constraints on the mass loss of 2.25 · 1011 g s−1 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. Conclusions. Our results suggest that WASP-69 b is going through a transformative phase of its history by losing mass while evolving on a misaligned orbit, similar to a growing number of Neptunian worlds. 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 in the near-infrared can reach precisions similar to HARPS in the optical for RM studies, and the high data quality of NIRPS leads to unprecedented atmospheric characterization. Therefore, the addition of NIRPS to HARPS on the ESO 3.6 m makes it the driving force of such new studies. The high stability of NIRPS combined with the large Guaranteed Time Observation (GTO) available for its consortium enables in-depth studies of exoplanets as well as large population surveys.
Blind search for activity-sensitive lines in the near-infrared using HARPS and NIRPS observations of Proxima and Gl 581 João Gomes da Silva, Elisa Delgado-Mena, Nuno C. Santos, Telmo Monteiro, Pierre Larue, et al. Astronomy and Astrophysics, 2025 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.
Diving into the planetary system of Proxima with NIRPS Breaking the metre per second barrier in the infrared Alejandro Suárez Mascareño, Étienne Artigau, Lucile Mignon, Xavier Delfosse, Neil J. Cook, et al. Astronomy and Astrophysics, 2025 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 ms−1 and a median uncertainty of 55 cms−1, 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⊕, and 0.260 ± 0.038 M⊕, 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−1, showcasing the potential of NIRPS to measure precise radial velocities in the near-infrared.
NIRPS joining HARPS at ESO 3.6 m On-sky performance and science objectives François Bouchy, René Doyon, Francesco Pepe, Claudio Melo, Étienne Artigau, et al. Astronomy and Astrophysics, 2025 Context. The Near-InfraRed Planet Searcher (NIRPS) is a high-resolution, high-stability near-infrared (NIR) spectrograph equipped with an adaptive optics (AO) system. Installed on the ESO 3.6-m telescope at La Silla Observatory, Chile, it was developed to enable radial velocity (RV) measurements of low-mass exoplanets around M dwarfs and to characterise exoplanet atmospheres in the NIR. Aims. This paper provides a comprehensive design overview and characterisation of the NIRPS instrument, reporting on its on-sky performance, advising on how to carry out observations, and presenting its guaranteed time observation (GTO) programme. Methods. Intensive on-sky testing phases were conducted between November 2019 and March 2023. The instrument started its operations on 1 April 2023. Results. The spectral range continuously covers the Y, J, and H bands from 972.4 to 1919.6 nm. The thermal control system maintains 1 mK stability over several months, thereby minimising drift. The NIRPS’s AO-assisted fibre link improves coupling efficiency and offers a unique high-angular resolution capability with a fibre acceptance of only 0.4″. A high spectral resolving power of R ~ 90 000 and R ~ 75 000 is provided in high-accuracy (HA) and high-efficiency (HE) modes, respectively. The overall throughput from the top of the atmosphere to the detector peaks at 13%. The RV precision, measured on the bright star Proxima with a known exoplanetary system, is 77 cms−1. NIRPS and HARPS can be used simultaneously, offering unprecedented spectral coverage for spectroscopic characterisation and stellar activity mitigation. Modal noise can be aptly mitigated by the implementation of fibre stretchers and AO scanning mode. Conclusions. Initial results confirm that NIRPS opens new possibilities for RV measurements, stellar characterisation, and exoplanet atmosphere studies with high precision and high spectral fidelity. NIRPS demonstrated stable RV precision at the level of 1 m s−1 over several weeks. The instrument’s high throughput, particularly in the H band, offers a notable improvement over previous spectrographs, enhancing our ability to detect small exoplanets.
NIRPS Front-End: Design, performance, and lessons learned Nicolas Blind, Uriel Conod, Allan de Meideros Martins, François Wildi, Francois Bouchy, et al. Proceedings of SPIE the International Society for Optical Engineering, 2022
NIRPS: A stepping stone for AO-fed high-resolution spectroscopy on ELTs Ao4elt 2019 Proceedings 6th Adaptive Optics for Extremely Large Telescopes, 2019
