Explanipedia

Detailed cool star flare morphology with CHEOPS and TESS <i>(Corrigendum)</i> Open

G. Bruno, I. Pagano, A. Brandeker, G. Olofsson, A. Fortier , et al. · 2025

A Decade of Solar High-Fidelity Spectroscopy and Precise Radial Velocities from HARPS-N Open

X. Dumusque, Khaled Al Moulla, M. Cretignier, N. Buchschacher, D. Ségransan , et al. · 2025

We recently released 10 years of HARPS-N solar telescope and the goal of this manuscript is to present the different optimisations made to the data reduction, to describe data curation, and to perform some analyses that demonstrate the ext…

An ultra-short period super-Earth and sub-Neptune spanning the Radius Valley orbiting the kinematic thick disc star TOI-2345 Open

Yoshi Nike Emilia Eschen, T. G. Wilson, A. Bonfanti, C. M. Persson, S. G. Sousa , et al. · 2025

A crucial chemical link between stars and their orbiting exoplanets is thought to exist. If universal, this connection could affect the formation and evolution of all planets. Therefore, this potential vital link needs testing by character…

NIRPS and TESS reveal a peculiar system around the M dwarf TOI-756: A transiting sub-Neptune and a cold eccentric giant Open

Léna Parc, F. Bouchy, Neil J. Cook, Nolan Grieves, Étienne Artigau , et al. · 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 p…

Quantifying thermal water dissociation in the dayside photosphere of WASP-121 b using NIRPS Open

Neil J. Cook, Khaled Al Moulla, Étienne Artigau, S. C. C. Barros, F. Bouchy , et al. · 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 therma…

Spectral analysis of two directly imaged benchmark L dwarf companions at the stellar-substellar boundary Open

W. Ceva, Elisabeth C. Matthews, Emily Rickman, D. Ségransan, A. Vigan , et al. · 2025

We used multiple epochs of high-contrast imaging spectrophotometric observations to determine the atmospheric characteristics and thermal evolution of two previously detected benchmark L dwarf companions, HD 112863 B and HD 206505 B. We an…

Chromaticity of stellar activity in radial velocities Open

P. Larue, X. Delfosse, A. Carmona, N. Meunier, Étienne Artigau , et al. · 2025

Context . In the search for exoplanets using radial velocities (RV), stellar activity has become one of the main limiting factors for detectability. Fortunately, activity-induced RV signals are wavelength-dependent or chromatic, unlike pla…

A comprehensive study on radial velocity signals using ESPRESSO: Pushing precision to the 10 cm/s level Open

P. Figueira, J. P. Faria, A. M. Silva, A. Castro-González, J. Gomes da Silva , et al. · 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 t…

Radial velocity homogeneous analysis of M dwarfs observed with HARPS Open

L. Mignon, X. Delfosse, N. Meunier, Guillaume Chaverot, Remo Burn , et al. · 2025

Aims . We aim to re-determine planetary occurrences around M dwarfs using 20 years of observations from HARPS on 197 targets. The first aim of this study is to propose more precise occurrence rates using the large volume of the sample but …

Hydride ion continuum hides absorption signatures in the NIRPS near-infrared transmission spectrum of the ultra-hot gas giant WASP-189b Open

Valentina Vaulato, Stefan Pelletier, D. Ehrenreich, R. Allart, E. Cristo , et al. · 2025

Context . Ultra-hot Jupiters showcase one-of-a-kind extreme atmospheric conditions, including the dissociation of molecules into atomic species, ionisation, and significant day-to-night temperature contrasts. The proximity to their host st…

Diving into the planetary system of Proxima with NIRPS Open

A. Suárez Mascareño, Étienne Artigau, L. Mignon, X. Delfosse, Neil J. Cook , et al. · 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 uncertai…

NIRPS detection of delayed atmospheric escape from the warm and misaligned Saturn-mass exoplanet WASP-69 b Open

R. Allart, Yann Carteret, V. Bourrier, L. Mignon, Frédérique Baron , et al. · 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 …

Geometric albedo of WASP-12 b and WASP-76 b in the CHEOPS and TESS bandpasses (<i>Corrigendum</i>) Open

Patricio E. Cubillos, O. D. S. Demangeon, B. Akinsanmi, Y. Alibert, R. Alonso , et al. · 2025

International audience

A comprehensive study on radial velocity signals using ESPRESSO: Pushing precision to the 10 cm/s level Open

P. Figueira, A. M. Silva, A. Castro-González, J. Gomes da Silva, S. G. Sousa , et al. · 2025

We analyse ESPRESSO data for the stars HD10700, HD20794, HD102365, and HD304636 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 timesc…

CORALIE radial-velocity search for companions around evolved stars (CASCADES) Open

E. Fontanet, S. Udry, D. Ségransan, P. Figueira, J.A. Acevedo Barroso , et al. · 2025

Context . With around 200 detections of exoplanets around giant stars to date, our knowledge of the population of exoplanets orbiting evolved hosts more massive than the Sun remains limited. The CORALIE radial-velocity search for companion…

The KELT-7b atmospheric thermal-inversion conundrum revisited with CHEOPS, TESS, and additional data Open

Z. Garai, A. Krenn, Patricio E. Cubillos, G. Bruno, A. M. S. Smith , et al. · 2025

Context . Early theoretical works suggested that ultrahot Jupiters have inverted temperature-pressure (T–P) profiles in the presence of optical absorbers, such as TiO and VO. Recently, an inverted T–P profile of KELT-7b was detected, in ag…

The KELT-7b atmospheric thermal-inversion conundrum revisited with CHEOPS, TESS, and additional data Open

Z. Garai, A. Krenn, P. E. Cubillos, G. Bruno, Allison Smith , et al. · 2025

Ultrahot Jupiters are predicted to show inverted temperature-pressure (T-P) profiles in the presence of optical absorbers such as TiO and VO. An inverted T-P profile of KELT-7b was recently detected, in line with these predictions, but suc…

CHEOPS observations confirm nodal precession in the WASP-33 system Open

A. M. S. Smith, Sz. Csizmadia, V. Van Grootel, M. Lendl, C. M. Persson , et al. · 2024

Aims . We aim to observe the transits and occultations of WASP-33 b, which orbits a rapidly rotating δ Scuti pulsator, with the goal of measuring the orbital obliquity via the gravity-darkening effect, and constraining the geometric albedo…

A possible misaligned orbit for the young planet AU Mic c Open

Haocun Yu, Z. Garai, M. Cretignier, Gyula M. Szabó, S. Aigrain , et al. · 2024

The AU Microscopii planetary system is only 24 Myr old, and its geometry may provide clues about the early dynamical history of planetary systems. Here, we present the first measurement of the Rossiter-McLaughlin effect for the warm sub-Ne…

Hints of a close outer companion to the ultra-hot Jupiter TOI-2109 b Open

Jan‐Vincent Harre, A. M. S. Smith, S. C. C. Barros, V. Singh, J. Korth , et al. · 2024

Context . Hot Jupiters (HJs) with close-by planetary companions are rare, with only a handful of them having been discovered so far. This could be due to their suggested dynamical histories, which lead to the possible ejection of other pla…

Architecture of TOI-561 planetary system Open

G. Piotto, T. Zingales, L. Borsato, J. A. Egger, A. C. M. Correia , et al. · 2024

We present new observations from CHEOPS (CHaracterising ExOPlanet Satellite) and TESS (Transiting Exoplanet Survey Satellite) to clarify the architecture of the planetary system hosted by the old Galactic thick disc star TOI-561. Our globa…

Revisiting the multi-planetary system of the nearby star HD 20794 Open

N. Nari, X. Dumusque, N.C. Hara, A. Suárez Mascareño, M. Cretignier , et al. · 2024

Context. Close-by Earth analogs and super-Earths are of primary importance because they will be preferential targets for the next generation of direct imaging instruments. Bright and close-by G-to-M type stars are preferential targets in r…

The CHEOPS view of the climate of WASP-3 b Open

G. Scandariato, L. Carone, Patricio E. Cubillos, P. F. L. Maxted, T. Zingales , et al. · 2024

Context . Hot Jupiters are giant planets subject to intense stellar radiation. The physical and chemical properties of their atmosphere make them the most amenable targets for atmospheric characterization. Aims . In this paper we analyze t…

The CHEOPS view on the climate of WASP-3 b Open

G. Scandariato, L. Carone, P. E. Cubillos, P. F. L. Maxted, T. Zingales , et al. · 2024

Hot Jupiters are giant planets subject to intense stellar radiation. The physical and chemical properties of their atmosphere makes them the most amenable targets for the atmospheric characterization. In this paper we analyze the photometr…

The K2-24 planetary system revisited by CHEOPS Open

V. Nascimbeni, L. Borsato, P. Leonardi, S. G. Sousa, T. G. Wilson , et al. · 2024

The planetary system K2-24 is composed of two transiting low-density Neptunians locked in an almost perfect 2:1 resonance and showing large transit time variations (TTVs), and it is an excellent laboratory to search for signatures of plane…

Characterisation of the warm-Jupiter TOI-1130 system with CHEOPS and a photo-dynamical approach Open

L. Borsato, David Degen, A. Leleu, M. J. Hooton, J. A. Egger , et al. · 2024

Context: Among the thousands of exoplanets discovered to date, approximately a few hundred gas giants on short-period orbits are classified as ‘lonely’ and only a few are in a multi-planet system with a smaller companion on a close orbit. …

Upgrading SPHERE with the second stage AO system SAXO+: frequency-based data-driven controller for adaptive optics Open

Isaac Bernardino Dinis, F. Wildi, D. Ségransan, Vaibhav Gupta, Alireza Karimi , et al. · 2024

This study introduces a novel frequency-based data-driven controller for adaptive optics, using power spectral density for optimization while ensuring stability criteria. It addresses disturbance rejection, command amplitude constraints an…

Unveiling the internal structure and formation history of the three planets transiting HIP 29442 (TOI-469) with CHEOPS Open

J. A. Egger, H. P. Osborn, Daria Kubyshkina, C. Mordasini, Y. Alibert , et al. · 2024

Multiplanetary systems spanning the radius valley are ideal testing grounds for exploring the different proposed explanations for the observed bimodality in the radius distribution of close-in exoplanets. One such system is HIP 29442 (TOI-…

Photo-dynamical characterisation of the TOI-178 resonant chain Open

A. Leleu, J. -B. Delisle, L. Delrez, Edward M. Bryant, A. Brandeker , et al. · 2024

Context . The TOI-178 system consists of a nearby, late-K-dwarf with six transiting planets in the super-Earth to mini-Neptune regime, with radii ranging from to 2.9 R ⊕ and orbital periods between 1.9 and 20.7 days. All the planets, but t…

Resonant sub-Neptunes are puffier Open

A. Leleu, J.-B. Delisle, Remo Burn, André Izidoro, S. Udry , et al. · 2024

A systematic, population-level discrepancy exists between the densities of exoplanets whose masses have been measured with transit timing variations (TTVs) versus those measured with radial velocities (RVs). Since the TTV planets are predo…

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