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Diving into the planetary system of Proxima with NIRPS -- Breaking the metre per second barrier in the infrared

T0 review · 2 major / 5 minor · reviewed 2026-08-06 · deepseek-v4-flash

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Pith's one-line read NIRPS infrared radial velocities reach 55 cm/s precision on Proxima, independently detect Proxima b, and, combined with HARPS and archival data, confirm the sub-Earth Proxima d.

desk verdict NIRPS reaches sub-m/s on Proxima — solid, thorough paper, but the Proxima d confirmation leans more on ESPRESSO than the abstract lets on. read the letter →

arxiv 2507.21751 v1 pith:EWNP4EO3 submitted 2025-07-29 astro-ph.EP astro-ph.IMastro-ph.SR

Alejandro Suárez Mascareño , Étienne Artigau , Lucile Mignon , Xavier Delfosse , Neil J. Cook , François Bouchy , René Doyon , Jonay I. González Hernández
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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 Stan Metchev Leslie Moranta Dany Mounzer Nicola Nari Louise D. Nielsen Ares Osborn Mathieu Ouellet Jon Otegi Léna Parc Luca Pasquini Vera M. Passegger Stefan Pelletier Céline Peroux Caroline Piaulet-Ghorayeb Mykhaylo Plotnykov Emanuela Pompei Anne-Sophie Poulin-Girard José Luis Rasilla Vladimir Reshetov Jonathan Saint-Antoine Mirsad Sarajlic Ivo Saviane Robin Schnell Alex Segovia Julia Seidel Armin Silber Peter Sinclair Michael Sordet Danuta Sosnowska Avidaan Srivastava Márcio A. Teixeira Simon Thibault Philippe Vallée Valentina Vaulato Joost P. Wardenier Bachar Wehbe Drew Weisserman Ivan Wevers François Wildi Vincent Yariv Gérard Zins
This is my paper · ORCID
classification astro-ph.EPastro-ph.IMastro-ph.SR
keywords radialvelocitynear-infraredspectroscopyexoplanetdetectionMdwarfstellaractivityGaussianprocessregressionProximabd
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

This paper claims that NIRPS, a near-infrared spectrograph on the 3.6-m ESO telescope, reaches a median radial-velocity uncertainty of $55\ \mathrm{cm\,s^{-1}}$ on Proxima, the closest star to the Sun, with post-fit residuals near $80\ \mathrm{cm\,s^{-1}}$ — a metre-per-second barrier crossed in the infrared for the first time. From 149 nights of its own data the paper independently detects the habitable-zone planet Proxima b at about 11σ, while the 5.12-day sub-Earth Proxima d appears at only about 2σ in NIRPS alone and gains confirmation only when NIRPS is combined with simultaneously taken HARPS spectra and 24.5 years of archival data. The adopted model measures Proxima b with minimum mass $1.055 \pm 0.055\ M_\oplus$ and Proxima d with minimum mass $0.260 \pm 0.038\ M_\oplus$, argues both signals are stable over time and consistent across instruments, and leaves the candidate Proxima c unconfirmed. If these claims hold, infrared RVs are a competitive, not merely complementary, channel for finding and confirming Earth-mass planets around the cool faint stars that visible-light spectrographs struggle to observe.

What carries the argument

The argument is carried by a multidimensional Gaussian process in which a single underlying activity function $G(t)$ appears in every time series — photometry, line-width variations, visible RVs, and infrared RVs — as a linear combination of $G$ and its time derivative $G'(t)$, the FF′ spot-modelling formalism. The GP kernel is the sum of two stochastic harmonic oscillators, one at the rotation period $P_\mathrm{rot} \simeq 83$ days and one at $P_\mathrm{rot}/2$; the authors chose this kernel specifically because quasi-periodic alternatives suppressed long-period signals in photometric tests. Around the GP sit a four-sinusoid magnetic-cycle model, polynomial detrending against the chromatic index and barycentric velocity, and circular or Keplerian planet terms; velocities are produced by a line-by-line template-matching code and detection significance is scored by the False Inclusion Probability framework.

What would settle it

A decisive test is to keep NIRPS observing Proxima until the 5.12-day signal can be found in a fully blind search with no period prior from visible-light data: at the claimed amplitude and $55\ \mathrm{cm\,s^{-1}}$ precision, roughly two more years of the same cadence should push the detection past $5\sigma$, and its recovered amplitude should match $39.2 \pm 5.7\ \mathrm{cm\,s^{-1}}$; a blind detection that fails, or lands at a different amplitude, would falsify the confirmation, as would a companion injection test in which a synthetic $39\ \mathrm{cm\,s^{-1}}$ planet at 5.12 days is not recovered by the same pipeline at comparable significance.

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Extended reading notes

Core claim

The central claim, stated by the paper as 'in the case of Proxima, NIRPS provides more precise radial velocity data than HARPS, and a more significant detection of the planetary signals,' rests on a same-baseline, same-cadence comparison: NIRPS and HARPS observed the star simultaneously through a dichroic splitter, and the infrared data had median uncertainties of $55\ \mathrm{cm\,s^{-1}}$ against $1.4\ \mathrm{m\,s^{-1}}$ for HARPS, with post-fit residual RMS of $0.81\ \mathrm{m\,s^{-1}}$ against $2.77\ \mathrm{m\,s^{-1}}$. The joint model measures Proxima b with period $11.18465 \pm 0.00053$ days and semi-amplitude $1.226 \pm 0.062\ \mathrm{m\,s^{-1}}$, and Proxima d with period $5.12338 \pm 0.00035$ days and semi-amplitude $39.2 \pm 5.7\ \mathrm{cm\,s^{-1}}$, both parameters consistent with the ESPRESSO-based results they extend. Apodised-signal tests place both signals at stable amplitude across the full 24.5-year baseline, and independent per-instrument fits agree within $1\sigma$, which the paper uses to argue the 5.12-day signal is a planet present in more than one instrument and not a product of the activity model. The paper does not confirm Proxima c and reports an updated magnetic-cycle length of $6560 \pm 85$ days, approximately twice the previously published value.

Load-bearing premise

The load-bearing premise is that the two-oscillator Gaussian process plus the four-sinusoid cycle model removes all stellar activity and instrumental signals down to periods of a few days, so that the $39.2 \pm 5.7\ \mathrm{cm\,s^{-1}}$ signal at 5.12 days is planetary rather than leftover activity.

Editorial extensions

If this is right

  • NIRPS already measures Proxima b's $1.23\ \mathrm{m\,s^{-1}}$ amplitude at about $11\sigma$ in its own data, so sub-metre-per-second planets become detectable around M dwarfs without 8-m class telescopes.
  • The refined ephemerides cut the 2026 prediction uncertainty for Proxima b from about 6 hours to about 3 hours, directly improving the scheduling of planned atmospheric-characterisation observations.
  • Residual RMS of $80\ \mathrm{cm\,s^{-1}}$ for NIRPS against $1.5\ \mathrm{m\,s^{-1}}$ for HARPS on the same star establishes that infrared precision spectroscopy is a viable route to Earth-mass planet detection at 4-m class facilities.
  • The 99% compatibility limits exclude planets above roughly $0.15\ M_\oplus$ inside 10 days and $0.3\ M_\oplus$ in the habitable zone, so the system's small inner planets are now confined to a narrow parameter space.
  • Proxima c is not confirmed, and the data permit at most a lower-amplitude signal near 1800 days, so the planetary architecture of Proxima is revised to a two-confirmed-planet system.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Because NIRPS and HARPS observed Proxima simultaneously through one dichroic splitter, the precision comparison is nearly free of time-span and sampling biases; repeating the same split-beam experiment on several other M dwarfs would show whether Proxima is a typical case or a favorable one for infrared RVs.
  • The paper's activity model leaves the 5.12-day signal at only about $2\sigma$ in NIRPS alone; if continued infrared monitoring raises it to a blind $5\sigma$ detection, the same strategy could resurrect several sub-Earth candidates around other M dwarfs that visible-light data alone cannot confirm.
  • The claimed $18$-year cycle, if real, predicts the photometric period-drift pattern (the butterfly-like diagram) to repeat; about a decade of continued photometry would discriminate it cleanly from the shorter 8-year cycle plus non-periodic trends, which the paper itself flags as the main unresolved ambiguity.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

2 major / 5 minor

Summary. The paper presents 149 nightly-binned NIRPS radial-velocity measurements of Proxima (420 spectra over 159 nights, 604-day baseline) with a median uncertainty of 55 cm/s and a post-fit residual RMS of approximately 80 cm/s. It performs a joint analysis of NIRPS, simultaneous HARPS, archival UVES/HARPS/ESPRESSO data, and long-term photometry, using a multidimensional Gaussian-process model with two SHO kernels and a four-sinusoid stellar-cycle model. The central claims are: an independent NIRPS detection of Proxima b; tentative NIRPS and NIRPS+HARPS evidence for Proxima d; confirmation of both signals in the combined dataset with FIP below the 1% threshold; refined ephemerides and masses; no conclusive detection of Proxima c; and a revised stellar cycle of about 18 years with signatures of differential rotation. The paper argues that NIRPS achieves sub-metre-per-second precision in the infrared for an M dwarf and outperforms HARPS under the same campaign conditions.

Significance. If the results hold, the paper demonstrates that a near-infrared spectrograph on a 3.6-m telescope can reach the sub-m/s RV regime for an M dwarf, provides an independent dataset for Proxima b, sharpens the ephemerides of b and d, and adds quantitative evidence on the candidate Proxima d. The analysis is unusually thorough: it uses multidimensional GP regression, an externally calibrated FIP detection framework, blind and guided searches, apodised-signal stability tests, per-instrument consistency checks, injection-recovery for Proxima c, and explicit comparisons of alternative GP kernels. The planned release of the data at CDS is a reproducibility strength. The principal caveat is that the instrument-independence and confirmation claims for Proxima d depend in part on guided fits and on the ESPRESSO dataset in which d was originally proposed; quantifying the non-ESPRESSO evidence is necessary before the strongest wording in the abstract can be defended.

major comments (2)
  1. [5.3.2, Fig. 12] The instrument-independence claim for Proxima d is not quantitatively supported. The UVES+HARPS+NIRPS comparison is a guided fit that adopts period priors centered on the Faria et al. (2022) solution, and no FIP, detection significance, or posterior probability K>0 is quoted for this subset. Since ESPRESSO is both the discovery instrument and a component of the full dataset, the statement in Section 6.2.2 that the signal is "present in instruments other than ESPRESSO" overreaches. Please report a blind or semi-blind false-inclusion probability for the non-ESPRESSO subset, or at minimum the posterior significance of K_d in the UVES+HARPS+NIRPS combination, and temper the abstract's instrument-independence claim accordingly.
  2. [5.1, 5.2, Abstract] The abstract's phrase "we find evidence of the presence of Proxima d in the NIRPS data" overstates the quantitative content of Section 5.1: the blind NIRPS search leaves the 5.12-day peak above the 1% FIP threshold, and the guided fit gives K = 32 +/- 14 cm/s, i.e., only about a 2-sigma amplitude. The NIRPS+HARPS GTO blind search reaches only FIP ~10%. Please either add a blind false-inclusion probability for NIRPS alone or rephrase the abstract to "tentative evidence" or "a signal consistent with Proxima d", reserving stronger confirmation language for the combined full dataset.
minor comments (5)
  1. [6.3.1, Conclusions] The quoted stellar cycle period is internally inconsistent: Section 6.3.1 and Table 2 give 6560 +/- 85 days (17.96 +/- 0.23 yr), while the Conclusions give 17.73 +/- 0.22 yr. Please harmonize the numbers and state explicitly that the 23.7-year photometric baseline covers only about 1.3 cycles, as the text itself acknowledges.
  2. [Fig. 18 caption] The caption refers to "the confirmed planets, Proxima b and Proxima c", but Proxima c is a candidate planet throughout the paper; it should say "Proxima b and the candidate Proxima c".
  3. [4.1, 5.3.3, Table G.1] The description in Section 4.1 says the cycle has a "common period and phase" for all time series, but Equation (2) uses independent phases for each harmonic; please rephrase to "common periods and per-harmonic phases". Also, Section 5.3.3 says the adopted model uses period priors with a range of +/-40%, whereas Table G.1 shows U(9.0,13.5) and U(4.1,6.1), which are approximately +/-20% around the adopted periods.
  4. [3.3, 6.2.5] There are several typographical and spacing errors that should be corrected, including "t was announced" in Section 3.3, "measuremets" in Section 3.1, and "conjuction" in Section 6.2.5; the many "di fficult"/"di fferent" spacing artifacts also suggest a final proofreading pass.
  5. [5.1, 5.2, 6.1] The NIRPS post-fit residual RMS is quoted as 81 cm/s, 84 cm/s, and 80 cm/s in different places; please use a single rounded value or explicitly state which model and dataset each number refers to.

Circularity Check

0 steps flagged · score 1.0 of 10

No circular derivation: blind searches carry the main detections; guided priors are labeled and non-forcing.

full rationale

The paper's central claims do not reduce to their inputs by construction. Proxima b is detected in a blind FIP search of the NIRPS-only dataset (Section 5.1, Fig. 3, FIP < 0.001%), with no prior from earlier work; the detection is confirmed by the simultaneous HARPS blind search and by the full-dataset blind search (Section 5.3, Fig. 9). For Proxima d, the paper is appropriately cautious: NIRPS alone yields only a ~2 sigma amplitude in a guided search (32 ± 14 cm/s, Section 5.1), and NIRPS+HARPS gives FIP ~ 10% blind (Section 5.2). The full-dataset blind search does detect d at FIP < 1%, but it includes the ESPRESSO data that originally proposed d; this is a joint re-analysis, not a circular prediction. The instrument-independence test (Section 5.3.2) uses guided priors centered on the authors' own Faria et al. (2022) period, but it is explicitly framed as a consistency check, and the amplitude and phase are left free, so the outcome is not forced by construction. The paper also states its own limitations: NIRPS alone cannot provide a significant detection of d, the HARPS 2023-2024 posterior is mostly flat, and the cycle period is difficult to disentangle from half-period alternatives. FIP thresholds come from the external Hara et al. (2022b) framework. Self-citations are present and used as informative priors, but they are disclosed and do not carry the blind detections. Thus the derivation is self-contained and no circular step meets the evidentiary bar.

Assumptions & free parameters 8 free parameters · 7 assumptions · 0 invented entities

The central planet detections sit on a large fitted activity model: a multidimensional GP, a four-harmonic cycle, per-instrument jitters, zero points, and detrending polynomials. These are not borrowed upstream constants but fitted nuisance parameters; the planet amplitudes are only as good as the model's ability to partition this variance. The paper's stability and kernel tests reduce, but do not eliminate, the risk that the GP absorbs or creates the 5-day signal.

free parameters (8)
  • GP rotation period = 83.2 ± 1.6 d
    Fitted in the joint photometry, FWHM, and RV model; sets the quasi-periodic activity timescale in Eqs 7-8.
  • GP evolution timescale = ln L = 4.07 ± 0.18 (L ≈ 59 d)
    Controls the coherence length of the activity process; a long L allows the GP to absorb low-frequency power, while a short L limits it.
  • GP mapping amplitudes A_i, B_i = A11=22.1, A12=8.9, A21=-12.2, A22=-5.5, A31=-14.6, A32=-0.29, A41=0.59, A42=1.33, A51=0.32, A52=-1.05, B21=39…
    These map the latent activity process and its derivative onto photometry, FWHM, and RVs (Eq 9); they absorb most of the stellar activity variance before planetary amplitudes are estimated.
  • Cycle period = 6560 +85/-82 d (17.96 yr)
    Determined mainly from photometry and applied to FWHM and RV through Eq 2; the authors note the baseline is shorter than two cycles, so the value is not definitive.
  • Cycle harmonic amplitudes = Phot: 32.7, 2.8, 5.1, 7.0 ppt; FWHM VIS: -6.3, -0.26, -0.80, -0.85 m/s; RV VIS: -0.89, 0.98, 0.63, -0.56 m/s
    Four-sinusoid model at P_cyc, P_cyc/2, P_cyc/3, P_cyc/4; needed to fit the non-sinusoidal cycle and prevent it leaking into planet periods.
  • White-noise jitter per instrument = ln sigma RV: NIRPS -0.55, HARPS-03 0.50, HARPS-15 0.43, ESP-18 -0.86, ESP-19 -1.22, UVES -0.08
    Added quadratically to the GP diagonal (Eq 7); absorbs unmodeled stellar and instrumental noise. The NIRPS jitter of about 0.58 m/s is comparable to the Proxima d signal of 0.39 m/s, so the detection depends on the GP partitioning the noise.
  • CRX and BERV detrending slopes = CRX: NIRPS 0.122, HARPS 0.0136, ESP 0.041; BERV: NIRPS a=0.036, b=0.0038; HARPS a=-0.0023, b=-0.0018; ESP a=0.038…
    Linear and quadratic terms against chromatic index and barycentric velocity (Eqs 10-11); remove instrument and telluric induced RVs; if misestimated, they can bias short-period signals.
  • Zero points per dataset = RV NIRPS -0.84, HARPS-03 0.74, HARPS-15 0.38, ESP-18 1.06, ESP-19 1.83, UVES 0.47 m/s
    Instrumental offsets in the joint model; errors here do not affect periods but do slightly affect absolute amplitudes.
assumptions (7)
  • standard math Keplerian orbital solution for circular and eccentric signals (Eqs 12-13)
    Used to convert RV time series into orbital parameters; standard background result, not proved in the paper.
  • domain assumption A single latent process G(t) and its gradient G'(t) generate the activity variations in all time series (Eq 6)
    The multidimensional GP framework (Rajpaul et al. 2015) assumes shared underlying activity; if false, the GP could misattribute planetary power to activity or vice versa.
  • ad hoc to paper Two SHO kernels at P_rot and P_rot/2 with quality factors set by the evolution timescale L (Eqs 7-8)
    Chosen from tests because it 'resulted in the lowest amount of overfitting of long-period signals' (Appendix A); other kernels suppressed long-period signals, so the choice influences which signals survive.
  • ad hoc to paper The stellar cycle is represented by four sinusoids at P_cyc, P_cyc/2, P_cyc/3, P_cyc/4 (Eq 2)
    A photometric-only model selection favored 4 harmonics; the cycle period is not uniquely determined given the baseline.
  • domain assumption NIR activity signals are a scaled version of VIS activity signals (Eq 5)
    Assumes the same shape and phase of activity-induced RV and FWHM variations in NIR and VIS, differing only by a constant scale; the authors note the chromatic effect is small but not perfectly in phase (Section 6.3.3).
  • domain assumption Instrumental and systematic RV effects are removable with linear and quadratic polynomials in CRX and BERV (Eqs 10-11)
    Residual telluric, detector, and stitching effects are assumed to follow these smooth trends; unsupported residual structure would enter the planet fit.
  • domain assumption FIP thresholds (1% conservative, 50% optimistic) from Hara et al. (2022b) are valid for this dataset
    Used to claim detection significance; the calibration is from simulations by the same group, not re-derived here.

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Cite this review

Pith. "Pith review of Diving into the planetary system of Proxima with NIRPS -- Breaking the metre per second barrier in the infrared." pith.science (2026). https://pith.science/paper/EWNP4EO3

@misc{pith2026250721751,
  author       = {Pith},
  title        = {Pith review of: Diving into the planetary system of Proxima with NIRPS -- Breaking the metre per second barrier in the infrared},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/EWNP4EO3}},
  note         = {Machine review of arXiv:2507.21751}
}
abstract

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 $\pm$ 0.055 Me, and 0.260 $\pm$ 0.038 Me, 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.

Figures

Figures reproduced from arXiv: 2507.21751 by the authors.

Figure 1
Figure 1. NIRPS GTO data. The upper panel shows the nightly-binned RV data of NIRPS and HARPS, obtained by the NIRPS GTO. The upper￾middle panel shows the time series of FWHM of the same spectra. The lower-middle panel shows the CRX data. The lower panel shows the BERV at which the measurements were taken. All data has its median value subtracted. with a typical exposure time of 400 s, and 1–3 exposures per visit, matching th… view at source ↗
Figure 2
Figure 2. All data. The upper panel shows the combined RV time series of Proxima. The upper-middle panel shows the time series of FWHM of the same spectra. The middle panel shows the CRX data. The lower-middle panel shows the BERV at which the measurements were taken. The lower panel shows the photometric data used in this work. sider separate datasets before and after, denoted ESPRESSO-18 (E18) and ESPRESSO-19 (E19). We redu… view at source ↗
Figure 3
Figure 3. FIP periodogram of the NIRPS-only model. [PITH_FULL_IMAGE:figures/full_fig_p009_3.png] view at source ↗
Figures from the paper (16 more)
Figure 4
Figure 4. Figure 4: Data and model of the NIRPS RV and DLW time series. [PITH_FULL_IMAGE:figures/full_fig_p010_4.png]
Figure 5
Figure 5. Figure 5: NIRPS phase-folded plots of the planetary-induced RV sig [PITH_FULL_IMAGE:figures/full_fig_p011_5.png]
Figure 7
Figure 7. Figure 7: FIP Periodogram of the NIRPS+HARPS 2023-2024 model. The highlighted peak corresponds to the period of 11.19 days of Prox￾ima b. The second weaker peak corresponds to 5.11 days, consistent with the period of Proxima d. -6 -4 -2 0 2 4 6 R V ( m / s ) Proxima b HARPS 15 N…
Figure 8
Figure 8. Figure 8: Phase-folded plots of the planetary-induced RV signals in [PITH_FULL_IMAGE:figures/full_fig_p011_8.png]
Figure 10
Figure 10. Figure 10: RV amplitudes. Posterior distributions of the amplitudes of the RV signals. The vertical dashed lines show the previously reported amplitudes of Proxima d, b, and c. We maintained the priors of N[11.1868, 0.1] days for Proxima b, and N[5.122, 0.05] days for Proxima d,…
Figure 9
Figure 9. Figure 9: FIP periodogram of the full dataset. The highlighted peaks corresponds to the period of 5.11 (Proxima d), and 11.19 (Proxima b). Following the same steps as with previous dataset, we start by performing a blind search. In this case, as the baseline is long enough, we t…
Figure 12
Figure 12. Figure 12: Comparison of the parameters between instruments. [PITH_FULL_IMAGE:figures/full_fig_p013_12.png]
Figure 13
Figure 13. Figure 13: RV model using the full dataset. The two top panels show the VIS RV data (detrended from CRX), with the best model fit (top), and the residuals after the fit (bottom), along with the periodograms of both (right). The two bottom panels show the same for the NIR RV data…
Figure 17
Figure 17. Figure 17: Comparison of RV residuals. Distribution of the residuals of the RV data after subtracting the best fit. The left panel includes all instruments. The right panel excludes ESPRESSO, for an easier visual￾ization of the rest. tion were not consistent with those previousl…
Figure 15
Figure 15. Figure 15: Phase-folded plots of the planetary-induced RV signals. [PITH_FULL_IMAGE:figures/full_fig_p016_15.png]
Figure 16
Figure 16. Figure 16: Comparison of the amplitudes of NIRPS with other instru [PITH_FULL_IMAGE:figures/full_fig_p016_16.png]
Figure 18
Figure 18. Figure 18: Compatibility limits. The upper panel shows the RV amplitude limit (99%) as a function of orbital period. The blue shaded bars show the periods of the confirmed planets, Proxima b and Proxima c. The orange shaded line shows the period of the candidate Proxima c. The g…
Figure 19
Figure 19. Figure 19: Comparison of the cycle models. Cycle model in Flux, FWHM, and RV, showing the relationship between the components. By modelling the cycle simultaneously in photometry, FWHM, and RV, we can compare its signature in all of them [PITH_FULL_IMAGE:figures/full_fig_p018_19.png]
Figure 21
Figure 21. Figure 21: Activity-induced RV variations. Activity-induced RV data from NIRPS and HARPS, after subtracting all planetary and instrumen￾tal effects. plex pattern. The difference in RV amplitude is smaller than what might be expected when extrapolating from past results on active…
Figure 22
Figure 22. Figure 22: Scaled dTEMP variations, compared to other activity prox [PITH_FULL_IMAGE:figures/full_fig_p019_22.png]
Figure 23
Figure 23. Figure 23: NIRPS dTEMP model. The top row shows the NIRPS dTEMP data, along with the best fit model, and the GLS periodogram of the data. The lower row shows the residuals after the fit, along with their periodogram. to 100 days, 1.0 M⊕ up to 1000 days, and to 4 M⊕ up to 10 000 …

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