arXiv subjects

C. Moutou

Publications and source records attributed to C. Moutou.

At least 19 recordsLinked to original sources

arXiv2026

Revisiting TOI-4438 and TOI-442 planetary systems with new observations from SPIRou and TESS

We present a comprehensive re-analysis of two star-planet systems: TOI-4438, an M3.5V star hosting a mini-Neptune in a 7.4-day orbit, and TOI-442, an M1V star with a 4-day period planet located within the hot Neptune desert. Both systems were originally identified as transiting planet candidates by TESS and subsequently validated through the radial velocity (RV) method. Our work incorporates new TESS transit data and high-resolution spectroscopy from the SPIRou near-infrared spectropolarimeter. We detect a persistent and relatively strong Zeeman signature in TOI-442, while TOI-4438 exhibits weaker and intermittent magnetic activity, and we infer the stellar rotation periods of both stars from the variability of the longitudinal magnetic field. We jointly fit photometry and RV models for each system. For TOI-4438\,b we combine archival CARMENES data with 81 SPIRou observations and five TESS sectors. This yields a refined planetary mass of $M_{\rm p} = 4.11^{+0.40}_{-0.38}\,M_{\oplus}$ and a radius of $R_{\rm p} = 2.40^{+0.09}_{-0.10}\,R_{\oplus}$, consistent with the previous estimate within 1.1$\sigma$ while improving by 53\% the precision on the mass and 22\% on the radius. For TOI-442\,b, we add 29 SPIRou RV measurements to an extensive archival dataset, significantly extending the temporal baseline. With a new TESS sector, we tighten the mass to $M_{\rm p} = 28.38^{+0.77}_{-0.73}\,M_{\oplus}$ and radius to $R_{\rm p} = 4.25^{+0.10}_{-0.08}\,R_{\oplus}$, which agrees to the previous values within 1.5$\sigma$ and improves the precisions by 46\% and 67\% respectively. We find no clear signs of additional planets in the available RV data, although we detect a single-transit event in the TOI-4438 light curve. We compare various RV models and find that those accounting for stellar variability-induced signals yield improved constraints on the planetary parameters.

astro-ph.EP↗

arXiv2026

Unstable magnetospheric accretion on the T Tauri star TW Hya

In this paper we present new spectropolarimetric and velocimetric observations of the prototypical classical T Tauri star TW Hya obtained with SPIRou at the Canada-France-Hawaii Telescope, expanding our previous monitoring over two new seasons (2024 and 2025). We confirm that the large-scale magnetic field of TW Hya varied with time, and find that it showed fluctuations on a timescale of about a year in addition to the longer term variations outlined in the previous study. Using Zeeman-Doppler imaging, we obtain that the large-scale field of TW Hya mostly consisted of a poloidal dipole of mean polar strength 0.83 kG, inclined at an average 17degr to the rotation axis. We also find that the radial velocities of TW Hya, once fully filtered from telluric contamination, were dominated by rotational modulation induced by activity, with residuals of 32 m/s rms. No signal from a putative close-in planet is found, with an upper limit on the planet mass ranging from 0.33 to 0.98 Mjup for distances of 0.053 to 0.41 au from the central star. Emission lines indicate that the mass accretion rate was equal to $10^{-8.33\pm0.20}$ Msun/yr on average, with peak-to-peak fluctuations by a factor of ~5 from season to season. This confirms that accretion onto TW Hya is unstable, with the magnetospheric gap carved by the large-scale field at the center of the disk extending on average no further than 33-40% of the corotation radius where the disk Keplerian angular velocity equals the rotation rate at the stellar surface.

astro-ph.SR↗

arXiv2026

The SPHERE infrared survey for exoplanets (SHINE) V. Full sample characterization

Unbiased surveys of large stellar samples are the prime means through which the prevalence of exoplanets can be derived, and crucial constraints to planet formation models can be set. Direct imaging (DI) is ideally positioned to probe the outer regions (5-300au) of planetary systems, providing complementary information to techniques such as transits and radial velocities. We present the full sample of the SpHere INfrared survey for Exoplanets (SHINE), the second largest DI campaign to date. SHINE observed 460 stars between 2015 and 2023 thanks to the guaranteed time observations (GTO) allocated by ESO to the SPHERE consortium at VLT. The goal of this paper is to homogeneously derive the stellar properties of the targets and to define a subsample of young single hosts to be used as a starting point for the final statistical analysis of the survey. Stellar ages were determined based on kinematic indicators (such as the membership to young moving groups), age diagnostics (lithium abundance, rotation, activity), and isochrone fitting. A thorough vetting for binarity was undertaken combining astrometric, spectroscopic, and imaging data. A subsample of 333 stars, covering a large extent of stellar ages and masses, was constructed. Selection criteria, global features, as well as the properties of individual stars are reported and discussed.

astro-ph.EP↗

arXiv2026

The GRAVITY young stellar object survey -- XV. The star-disk interaction region of the T Tauri star DO Tau

Protoplanetary disks around young Sun-like stars are the cradles of the vast majority of detected exoplanets. Probing these disks at multiple spatial scales is key to uncovering how planets form. We aim to spatially and spectrally resolve the inner disk and star-disk interaction region of the M0.3 T Tauri star DO Tau by combining two complementary techniques. We used high-resolution near-infrared spectra from CFHT/SPIRou to constrain the magnetospheric star-disk interaction process and optical long-baseline interferometry with ESO VLTI/GRAVITY to determine the sizes of the K-band continuum and Br$\gamma$ line emitting regions. From the SPIRou spectra, we confirmed that this ~0.5 M$_\odot$ star is a strong accretor. The HI and HeI lines exhibit strong variability on a daily timescale, consistent with the burster classification of DO Tau derived from its K2 light curve. We derived an upper limit of 0.35 on the ratio between the magnetospheric truncation radius and the disk corotation radius, indicative of an ordered unstable accretion regime. The size of the Br$\gamma$ line emitting region obtained from GRAVITY is much smaller than the K-band continuum emitting region. This compact Br$\gamma$ emission region ($R_{Br\gamma} \sim$ 0.011 au) suggests that most of the line flux originates from the magnetospheric accretion region and/or from an inner wind close to the magnetosphere-disk interface. The inclination we derived for the inner disk (45-55{\deg}) differs from that of the outer disk inferred from the ALMA continuum (30{\deg}). This points toward a misalignment or warp of the outer disk that may originate from the suspected past encounter with the neighboring HV Tau system.

astro-ph.SR↗

arXiv2026

Monitoring the magnetospheric accretion of the classical T Tauri star DO Tau with SPIRou

We present observations of the classical T Tauri star DO Tau collected with the near-infrared SPIRou spectropolarimeter and precision velocimeter at the Canada-France-Hawaii Telescope from early 2020 to late 2025. Circularly polarized Zeeman signatures were clearly detected at most epochs in the atomic spectral lines of DO Tau, yielding longitudinal magnetic fields of up to 280 G modulated with a period of 5.128+-0.002 d which we identified as the rotation period of DO Tau. Applying Zeeman-Doppler imaging to the SPIRou data recorded in 2021, 2024 and 2025, we found that DO Tau hosts an unusual large-scale magnetic field that is weaker, less poloidal, more inclined to the rotation axis, and varies more rapidly with time than those of previously studied T Tauri stars, possibly as a result of intense accretion between the inner disk and the stellar surface. The dipole component of this large-scale field of about 0.2-0.3 kG even flipped polarity toward the end of our observing campaign, making DO Tau the first T Tauri star for which a magnetic polarity reversal is reported. The magnetospheric gap surrounding the central star was quite compact, extending to ~1.6 Rstar (0.014 au) as a result of the strong accretion rate (log Mdot = -7.7 Msun/yr), with the inner accretion disk being warped by the tilted stellar magnetic field. Radial velocity variations suggest the presence of a close-in planet of a few Mjup or a density structure in the inner accretion disk at an orbital period of 21 d (corresponding to 0.12 au), which might be linked to the wiggle in the jet axis of DO Tau.

astro-ph.SR↗

arXiv2026

Atmospheric characterization of HIP 67522 b with VLT/CRIRES+. VLT/CRIRES+ suggests a heavier planet and hints at deuterium fractionation

Young transiting exoplanets provide unique opportunities to probe planetary atmospheres during the critical early phases of evolution. HIP 67522 b, a 17 Myr old hot Jupiter with an extraordinarily low bulk density, represents an ideal target for high-resolution transmission spectroscopy. We aim to characterize the atmospheric composition, thermal structure, and dynamics of HIP 67522 b using ground-based high-resolution near-infrared spectroscopy. We obtained high-resolution spectra with VLT/CRIRES+ in the K2166 band during a transit on 30 January 2025. We applied cross-correlation techniques and Bayesian nested sampling retrievals to constrain molecular abundances, temperature structure, and atmospheric dynamics. We detect H$_2$O at 20$\sigma$ and CO at 5$\sigma$, confirming the extremely extended atmosphere of this low-mass giant. A velocity offset of $-2.9 \pm 0.2$ km s$^{-1}$ indicates day-to-night winds. The rotation velocity is constrained to <1.8 km s$^{-1}$ at 3$\sigma$, consistent with tidal locking. Retrieval analysis suggests a planetary mass of 29.8 $\pm$ 3 Earth masses and a vertically isothermal atmosphere. This mass is two times larger than the mass estimated from JWST atmospheric observations and inconsistent at 3$\sigma$ hence leaving a doubt on the actual planetary density of the planet. Using the mass derived from the CRIRES+ data, we derive a C/O ratio of $0.83 \pm 0.09$, about 1.5 times solar, and a subsolar metallicity [C+O/H] $= -0.8 \pm 0.4$ which can be increased if the atmosphere is cloudy, a degeneracy our data alone cannot resolve. We report a tentative 2$\sigma$ detection of HDO with an extreme enrichment factor of $\sim$1000 relative to the protosolar D/H ratio. If confirmed, this would be the first detection of deuterium in an exoplanet atmosphere and would require intense escape rate to be explained.

astro-ph.EP↗

arXiv2026

The SPIRou Legacy Survey: Detection of a nearby world orbiting in the habitable zone of Gl725B achieved by correcting strong telluric contamination in near-infrared radial velocities with WAPITI

M dwarfs are prime targets in the search for exoplanets because of their prevalence and because low-mass planets can be better detected with radial velocity (RV) methods. In particular, the near-infrared (NIR) spectral domain offers an increased RV sensitivity and potentially reduced stellar activity signals. Howevern precise NIR RV measurements can be strongly affected by telluric absorption lines from the Earth's atmosphere. We searched for planets orbiting Gl 725 B, a nearby late-M dwarf at $3.5$ pc, using high-precision SPIRou RV observations. We assessed the impact of telluric contamination and evaluated the performance of the weighted principal component analysis reconstruction method (WAPITI), designed to mitigate these systematics and improve planet detectability. Using synthetic and observational SPIRou data, we simulated telluric effects on RVs under varying barycentric Earth radial velocity (BERV) conditions and applied WAPITI to correct line-by-line RVs. The method was tested through injection-recovery experiments and applied to real SPIRou observations of Gl 725 B. WAPITI efficiently corrects telluric contamination in simulated and real datasets, enhancing the detectability and accuracy of planetary signals. We identify a two-planet system around Gl 725 B composed of a candidate inner planet (Gl 725 Bb) with a period of $4.765 \pm 0.004$ days and semi-amplitude $1.4 \pm 0.3$ m.s$^{-1}$, and a confirmed outer planet (Gl 725 Bc) with a period of $37.90 \pm 0.17$ days and semi-amplitude $1.7 \pm 0.3$ m.s$^{-1}$. Their minimum masses are $1.5 \pm 0.4$ and $3.5 \pm 0.7$ M$_\oplus$, respectively, and the outer planet lies in the habitable zone. Using a multi-dimensional Gaussian process framework to model stellar activity, we also recover a stellar rotation period of $105.1 \pm 3.3$ days.

astro-ph.EP↗

arXiv2025

Searching for close-in planets around TWA 7 with SPIRou

We outline in this paper observations of the young pre-main-sequence low-mass star TWA 7, hosting a debris disk and a distant planet. Using data collected with the near-infrared SPIRou spectropolarimeter / precision velocimeter at the Canada-France-Hawaii Telescope from early 2019 to mid 2021, we detected the magnetic field of TWA 7 from the circularly polarized Zeeman signatures and Zeeman broadening of atomic spectral lines, and the rotational modulation of its longitudinal component at the known stellar rotation period (of 5.012+-0.007 d). We then modeled the large-scale and small-scale magnetic properties of TWA 7 using Zeeman-Doppler imaging. We found that TWA 7 hosted a mainly poloidal field that significantly evolved from 2019 to 2021, the dipole component getting stronger (increasing from 0.5 kG in 2019 to 0.7 kG in 2021) and less inclined to the stellar rotation axis (from 22{\deg} in 2019 to 15{\deg} in 2021). We also analyzed the radial velocities of TWA 7 derived from the SPIRou data, and found a tentative planet signature at a period of 15.2 d (with aliases at 20.8 and 30.4 d), very close to the detection limit of our data and that would correspond to a 0.17 Mjup planet at a distance of 0.09 au if confirmed. We finally report modulation of the 1083 nm He I and 1282 nm Pa-beta lines of TWA 7 with a period of 6.6 d, different from the rotation period and potentially hinting at the presence of a close-in planet triggering star-planet interactions.

astro-ph.SR↗

arXiv2025

Characterizing planetary systems with SPIRou: questions about the magnetic cycle of 55 Cnc A and two new planets around B

One of the first exoplanet hosts discovered thirty years ago, the star 55 Cnc has been constantly observed ever since. It is now known to host at least five planets with orbital periods ranging from 17 hours to 15 years. It is also one of the most extreme metal rich stars in the neighbourhood and it has a low-mass secondary star. In this article, we present data obtained at the Canada-France-Hawai'i Telescope with the SPIRou spectropolarimeter on both components of the 55 Cnc stellar system. We revisit the long-period radial-velocity signals of 55 Cnc A, with a focus on the role of the magnetic cycle, and propose the existence of a sixth planet candidate, whose period falls close to that of the magnetic cycle, or half of it. The other massive outer planet has a revised period of 13.15 years and a minimum mass of 3.8 MJup. Although some uncertainty remains on these outer planets, the characterization of the four inner planets is very robust through the combination of many different data sets, and all signals are consistent in the nIR and optical domains. In addition, the magnetic topology of the solar-type primary component of the system is observed by SPIRou at the minimum of its activity cycle, characterized by an amplitude ten times smaller than observed during its maximum in 2017. For the low-mass component 55 Cnc B, we report the discovery of two exoplanets in the system, with a period of 6.799+-0.0014 and 33.75+-0.04 days and a minimum mass of 3.5+-0.8 and 5.3+-1.4 MEarth, respectively. The secondary magnetic field is very weak and the current data set does not allow its precise characterization, setting an upper limit of 10 G. The system 55 Cnc stands out as the sixth binary system with planetary systems around both components, and the first one with non equal-mass stellar components.

astro-ph.EP↗

arXiv2025

Rotational modulation and long-term evolution of the small-scale magnetic fields of M dwarfs observed with SPIRou

M dwarfs are known to host magnetic fields, impacting exoplanet studies and playing a key role in stellar and planetary formation and evolution. Observations revealed the long-term evolution of the large-scale magnetic field reconstructed with Zeeman-Doppler imaging, and a diversity of their topologies. These large-scale magnetic fields only account for a small amount of the unsigned magnetic flux that can be probed by directly modeling the Zeeman broadening of spectral lines in unpolarized spectra. We aim at investigating the long-term behavior of the average small-scale magnetic field of M dwarfs with time, and assess our ability to detect rotational modulation from time series of field measurements derived from unpolarized spectra. We perform fits of synthetic spectra computed with ZeeTurbo to near-infrared high-resolution spectra recorded with SPIRou between 2019 and 2024 in the context of the SLS and SPICE large programs. The analysis is performed on the spectra of 2 partially convective (AD Leo, DS Leo) and 3 fully convective (PM J18482+0741, CN Leo, Barnard star) M dwarfs, along with EV Lac whose mass is close to the fully-convective limit. Our analysis provides measurements of the average small-scale magnetic field, which are compared to longitudinal magnetic field and temperature variation measurements (d$Temp$) obtained from the same data. We were able to detect the rotation period in the small-scale magnetic field series for 4 of the 6 stars in our sample. We find that the average magnetic field can vary by up to 0.3 kG throughout the year (e.g., CN Leo), or of up to 1 kG across rotation phases. The rotation periods retrieved from longitudinal and small-scale magnetic fields are found in agreement within error bars. d$Temp$ measurements are found to anti-correlate with small-scale magnetic field measurements for three stars (EV Lac, DS Leo and Barnard's star).

astro-ph.SR↗

arXiv2025

Six-yr SPIRou monitoring of the young planet-host dwarf AU Mic

In this paper we revisit our spectropolarimetric and velocimetric analysis of the young M dwarf AU Mic based on data collected with SPIRou at the Canada-France-Hawaii telescope, over a monitoring period of 2041 d from 2019 to 2024. The longitudinal magnetic field, the small-scale magnetic field, and the differential temperature of AU Mic, derived from the unpolarized and circularly-polarized spectra, were clearly modulated with the stellar rotation period, with a pattern that evolved over time. The magnetic modeling with Zeeman-Doppler imaging provides a consistent description of the global field of AU Mic that agrees not only with the Least-Squares Deconvolved profiles of the circularly-polarized and unpolarized spectral lines, but also with the small-scale field measurements derived from the broadening of spectral lines, for each of the 11 subsets of the full data. We find that the large-scale field was mostly poloidal, with a dominant dipole component slightly tilted to the rotation axis which decreased from 1.4 to 1.1 kG before increasing at the end of the campaign. The average small-scale field followed a similar trend, decreasing from 2.8 to 2.6 kG then rising. The long-term magnetic evolution we report for AU Mic suggests that, if cyclic, the cycle period is significantly longer than 6 yr. From velocimetric data, we derived improved mass estimates for the two transiting planets, respectively equal to M_b = 6.3+2.5-1.8 M_earth and M_c = 11.6+3.3-2.7 M_earth, yielding very contrasting densities of 0.32+0.13-0.10 and 2.9+1.1-0.8 g/cm3, and a new 90% confidence upper limit of 4.9 M_earth for candidate planet d (period 12.7 d) suspected to induce the transit-timing variations of b and c. We also confirm our claim regarding candidate planet e orbiting with a period of 33.11+-0.06 d, albeit with a smaller mass of M_e = 21.1+5.4-4.3 M_earth.

astro-ph.SR↗

arXiv2025

Full Stokes magnetometry of the active M dwarfs AU Mic and EV Lac with SPIRou

We report in this paper circularly and linearly polarized observations of the young active M dwarfs AU Mic and EV Lac with the near-infrared SPIRou spectropolarimeter at the Canada-France-Hawaii Telescope, collected from August to October 2023 over a few rotation cycles of both stars. Applying Least-Squares Deconvolution (LSD) to our spectra, we detected Zeeman signatures in circular (Stokes V) and linear (Stokes QU) polarization, and Zeeman broadening in unpolarized (Stokes I) LSD profiles, all exhibiting clear rotational modulation. Using the stellar surface tomographic technique of Zeeman-Doppler imaging on our sets of observations, along with a simple parametric description of how the small-scale and large-scale fields relate to each other, we recovered the magnetic topologies of AU Mic and EV Lac successively from LSD Stokes V, Stokes IV and Stokes IVQU profiles, to investigate how the reconstructed maps evolve as we provide more information, and ultimately infer reliable magnetic maps of both stars. We find that AU Mic hosts a fairly simple and mostly poloidal large-scale field aligned with the rotation axis within about 10deg, whereas that of EV Lac is more complex, stronger and less axisymmetric. Both stars feature intense small-scale fields, of about 4 kG for AU Mic and 6 kG for EV Lac when averaged over the whole stellar surface. Stokes QU Zeeman signatures allow one to reconstruct stellar magnetic fields more reliably, and are especially useful for stars with more complex fields and low vsini's like EV Lac.

astro-ph.SR↗

arXiv2025

Detecting and characterising the magnetic field of exoplanets

Magnetic fields play a crucial role in planetary evolution and habitability. While the intrinsic magnetic fields of solar system planets are relatively well understood, the magnetic properties of exoplanets remain largely unconstrained, despite their potential ubiquity. Detecting exoplanetary magnetic fields is essential to advancing our understanding of planetary habitability beyond the solar system. This paper focuses on two promising spectropolarimetric techniques for detecting magnetic fields in hot exoplanets: direct detection through polarization signatures in the He I 1083 nm triplet and indirect detection via star-planet magnetic interactions manifesting as stellar hot spots. The direct method is particularly suited to close-in gas giants, leveraging the Hanle and Zeeman effects to detect low-amplitude magnetic fields. The indirect method can apply to both giant and low-mass planets by identifying magnetic connectivity-induced features in the stellar atmosphere. Although the interpretation of current detections remain tentative, upcoming high-resolution spectropolarimetric capabilities in the UV and near-infrared, particularly with future missions like HWO, promise to enable definitive measurements of exoplanetary magnetic fields. These advancements will open new avenues for probing the magnetic environments of exoplanets and their implications for atmospheric retention and habitability.

astro-ph.IM↗

arXiv2025

Mass, Gas, and Gauss around a T Tauri Star with SPIRou

Studies of young planets help us understand planet evolution and investigate important evolutionary processes such as atmospheric escape. We monitored IRAS 04125+2902, a 3 Myr-old T Tauri star with a transiting planet and a transitional disk, with the SPIRou infrared spectropolarimeter on the Canada-France-Hawaii Telescope. Using these data, we constrained the mass and density of the Jupiter-size companion to <0.16 M_J and <0.23 g/cm^3, respectively (90\% upper limits). These rule out a Jovian-like object and support the hypothesis that it is an ancestor to the numerous sub-Neptunes found around mature stars. We unambiguously detect magnetic fields at the stellar surface, small-scale fields reaching 1.5 kG and the large-scale field mostly consisting of a 0.80-0.95 kG dipole inclined by 5-15deg to the rotation axis. Accretion onto the star is low and/or episodic at a maximum rate of ~10^{-11} Msun/yr, indicating that IRAS 04125+2902 is most likely in a magnetic 'propeller' regime, possibly maintaining the star's slow rotation (11.3~d). We discover persistent Doppler-shifted absorption in a metastable He I line, clear evidence for a magnetized wind from a gaseous inner disk. Variability in absorption suggests structure in the disk wind that could reflect disk-planet interactions.

astro-ph.SR↗

arXiv2025

Characterizing planetary systems with SPIRou: Detection of a sub-Neptune in a 6-day period orbit around the M dwarf Gl 410

The search for exoplanets around nearby M dwarfs represents a crucial milestone in the census of planetary systems in the vicinity of our Solar System. Since 2018 our team is carrying a radial-velocity blind search program for planets around nearby M dwarfs with the near-IR spectro-polarimeter and velocimeter SPIRou at the CFHT and the optical velocimeter SOPHIE at the OHP in France. Here we present our results on Gl 410, a 0.55 Msun 480+-150 Myr old active M dwarf distant 12 pc. We used the line-by-line (LBL) technique to measure the RVs with SPIRou and the template matching method with SOPHIE. Three different methods were employed, two based on principal component analysis (PCA), to clean the SPIRou RVs for systematics. We applied Gaussian processes (GP) modeling to correct the SOPHIE RVs for stellar activity. The l1 and apodize sine periodogram analysis was used to search for planetary signals in the SPIRou data taking into account activity indicators. We analyzed TESS data and searched for planetary transits. We report the detection of a M sin(i)=8.4+-1.3 Mearth sub-Neptune planet at a period of 6.020+-0.004 days in circular orbit with SPIRou. The same signal, although with lower significance, was also retrieved in the SOPHIE RV data after correction for activity using a GP trained on SPIRou's longitudinal magnetic field (Bl) measurements. The TESS data indicate that the planet is not transiting. Within the SPIRou wPCA RVs, we find tentative evidence for two additional planetary signals at 2.99 and 18.7 days. In conclusion, infrared RVs are a powerful method to detect extrasolar planets around active M dwarfs. Care should be taken however to correct/filter systematics generated by residuals of the telluric correction or small structures in the detector plane. The LBL technique combined with PCA offers a promising way to reach this objective. Further monitoring of Gl 410 is necessary.

astro-ph.EP↗

arXiv2025

The SPIRou Legacy Survey: near-infrared and optical radial velocity analysis of Gl 480 and Gl 382 using SPIRou, HARPS and CARMENES spectrographs

Context: Advancements in the field of exoplanetary research have extended radial velocity (RV) observations from the optical to the near-infrared (nIR) domain. M dwarf stars, characterized by their lower masses and higher prevalence of rocky planets, have become a focal point of investigation. This study uses data from the near-infrared spectropolarimeter SPIRou and data available in the literature from the HARPS and CARMENES spectrographs operating in the optical to analyze RVs of two nearby M dwarfs, Gl 480 and Gl 382. Aims: This work aims to detect and characterize exoplanetary companions around Gl 480 and Gl 382 by mitigating stellar activity effects through advanced data analysis techniques. The study seeks to improve the reliability of RV signals by integrating multi-wavelength observations and stellar activity diagnostics. Methods: The study employs a comprehensive approach that combines the line-by-line (LBL) framework with the Wapiti (Weighted principAl comPonent analysIs reconsTructIon) method to correct for systematics in SPIRou data. Through an extensive analysis of available stellar activity indicators and by combining optical data from the HARPS and CARMENES instruments, we perform a joint analysis of RV measurements in both the nIR and optical domains. Results: Our analysis confirms the detection of a planet orbiting Gl 480 with a period of $9.5537 \pm 0.0005$ d and a minimum mass of $8.8 \pm 0.7$ M$_\oplus$. Additionally, we detect a tentative signal at 6.4 d, whose significance depends strongly on the choice of Gaussian Process priors constrained by stellar activity indicators and would require further observations for confirmation. In contrast, no planetary signals are detected for Gl 382, where RV variations are dominated by stellar activity.

astro-ph.EP↗

arXiv2025

The SPHERE infrared survey for exoplanets (SHINE). V. Complete observations, data reduction and analysis, detection performances, and final results

During the past decade, state-of-the-art planet-finder instruments like SPHERE@VLT, coupling coronagraphic devices and extreme adaptive optics systems, unveiled, thanks to large surveys, around 20 planetary mass companions at semi-major axis greater than 10 astronomical units. Direct imaging being the only detection technique to be able to probe this outer region of planetary systems, the SPHERE infrared survey for exoplanets (SHINE) was designed and conducted from 2015 to 2021 to study the demographics of such young gas giant planets around 400 young nearby solar-type stars. In this paper, we present the observing strategy, the data quality, and the point sources analysis of the full SHINE statistical sample as well as snapSHINE. Both surveys used the SPHERE@VLT instrument with the IRDIS dual band imager in conjunction with the integral field spectrograph IFS and the angular differential imaging observing technique. All SHINE data (650 datasets), corresponding to 400 stars, including the targets of the F150 survey, are processed in a uniform manner with an advanced post-processing algorithm called PACO ASDI. An emphasis is put on the classification and identification of the most promising candidate companions. Compared to the previous early analysis SHINE F150, the use of advanced post-processing techniques significantly improved by one or 2 magnitudes (x3-x6) the contrast detection limits, which will allow us to put even tighter constraints on the radial distribution of young gas giants. This increased sensitivity directly places SHINE as the largest and deepest direct imaging survey ever conducted. We detected and classified more than 3500 physical sources. One additional substellar companion has been confirmed during the second phase of the survey (HIP 74865 B), and several new promising candidate companions are awaiting second epoch confirmations.

astro-ph.EP↗

arXiv2024

Characterization of seven transiting systems including four warm Jupiters from SOPHIE and TESS

We present the study of seven systems, three of which TOI-2295, TOI-2537, and TOI-5110 are newly discovered planetary systems. Through the analysis of TESS photometry, SOPHIE radial velocities, and high-spatial resolution imaging, we found that TOI-2295b, TOI-2537b, and TOI-5110b are transiting warm Jupiters with orbital periods ranging from 30 to 94 d, masses between 0.9 and 2.9 MJ, and radii ranging from 1.0 to 1.5 RJ. Both TOI-2295 and TOI-2537 each harbor at least one additional, outer planet. Their outer planets TOI-2295c and TOI-2537c are characterized by orbital periods of 966.5 +/- 4.3 and 1920^{+230}_{-140} d, respectively, and minimum masses of 5.61^{+0.23}_{-0.24} and 7.2 +/- 0.5 MJ, respectively. We also investigated and characterized the two recently reported warm Jupiters TOI-1836b and TOI-5076b, which we independently detected in SOPHIE RVs. Additionally, we study the planetary candidates TOI-4081.01 and TOI-4168.01. For TOI-4081.01, despite our detection in radial velocities, we cannot rule out perturbation by a blended eclipsing binary and thus exercise caution regarding its planetary nature. On the other hand, we identify TOI-4168.01 as a firm false positive. Finally, we highlight interesting characteristics of these new planetary systems. The transits of TOI-2295b are highly grazing, with an impact parameter of 1.056$^{+0.063}_{-0.043}$. TOI-2537b, in turn, is a temperate Jupiter with an effective temperature of 307+/-15 K and can serve as a valuable low-irradiation control for models of hot Jupiter inflation anomalies. We also detected significant transit timing variations (TTVs) for TOI-2537b, which are likely caused by gravitational interactions with the outer planet TOI-2537c. Finally, TOI-5110b stands out due to its orbital eccentricity of 0.75+/- 0.03, one of the highest planetary eccentricities discovered thus far.

astro-ph.EP↗