Explanipedia

Ever Elusive Exospheres: One Probable Detection and Two Nondetections of H α Transits in Young Systems Open

Andrew W. Mann, Erin Flowers, A. Heitzmann, Benjamin T. Montet, George Zhou · 2025

Gaps in the exoplanet population, such as the Neptunian Desert, point to the importance of mass loss in sculpting the radii of close-in exoplanets. Young planets (<500 Myr) offer the opportunity to detect such mass loss while it is still s…

HARPS-N, TESS, and CHEOPS discover a transiting sub-Neptune and two outer companions around the bright solar analogue HD 85426 Open

A. Mortier, A. Collier Cameron, M. Cretignier, A. Anna John, J. A. Egger , et al. · 2025

We provide a detailed characterisation of the planetary system orbiting HD 85426 (TOI-1774). This bright G-type star (M*: 0.99 M⊙; R*: 1.13 R⊙; age: 7.4 Gyr; V mag: 8.25) hosts a transiting sub-Neptune, HD 85426 b, with an orbital period o…

HARPS-N, TESS, and CHEOPS discover a transiting sub-Neptune and two outer companions around the bright solar analogue HD 85426 Open

F. Lienhard, A. M. J. Mortier, A. Collier Cameron, L. Borsato, A. Anna John , et al. · 2025

We provide a detailed characterisation of the planetary system orbiting HD 85426 (TOI-1774). This bright G-type star ($M_{\ast}$: 0.99 $\text{M}_{\odot}$; $R_{\ast}$: 1.13 $\text{R}_{\odot}$; age: 7.4 Gyr; V mag: 8.25) hosts a transiting s…

Detailed cool star flare morphology with CHEOPS and TESS (Corrigendum) Open

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

CHEOPS ground segment: Systems and automation for mission and science operations Open

A. Heitzmann, María José González Bonilla, A. Bekkelien, B. Akinsanmi, M. Beck , et al. · 2025

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…

An Ultra-Short Period Super-Earth and Sub-Neptune Spanning the Radius Valley Orbiting the Kinematic Thick Disk 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…

Improved characterization of the TOI-2141 system: A dense sub-Neptune with non-transiting inner and outer companions Open

R. Luque, K. W. F. Lam, J. Cabrera, A. Bonfanti, Yoshi Nike Emilia Eschen , et al. · 2025

Aims. We aim to refine the fundamental parameters of the TOI-2141 planetary system, which includes a transiting sub-Neptune orbiting a Sun-like star on a relatively long orbit of 18.26 days, by combining new photometric and spectroscopic o…

Transit timing variations in HIP 41378: CHEOPS and TESS confirm a non-transiting sixth planet in the system Open

P. Leonardi, L. Borsato, L. Pagliaro, Daria Kubyshkina, J.A. Egger , et al. · 2025

In multiple-planet systems, gravitational interactions of exoplanets could lead to transit timing variations (TTVs), whose amplitude becomes significantly enhanced when planets are in or near mean-motion resonances (MMRs), making them more…

A four-planet system orbiting the old thick disk star TOI-1203 Open

D. Gandolfi, A. Alnajjarine, L. M. Serrano, J. A. Egger, K. W. F. Lam , et al. · 2025

TOI-1203 is a bright (V=8.6) G3 V star known to host a transiting warm sub-Neptune on a 25.5 d orbit. Here we report on an intensive high-precision radial velocity and photometric follow-up campaign carried out with the HARPS spectrograph …

ATREIDES Open

V. Bourrier, M. Steiner, A. Castro-González, D. J. Armstrong, O. Attia , et al. · 2025

The distribution of close-in exoplanets is shaped by a complex interplay between atmospheric and dynamical processes. The Desert, Ridge, and Savanna (respectively a lack, overoccurence, and mild deficit of Neptunes with increasing periods)…

Improved characterization of the TOI-2141 system: a dense sub-Neptune with non-transiting inner and outer companions Open

R. Luque, J. Cabrera, A. Bonfanti, Yoshi Nike Emilia Eschen, G. Olofsson , et al. · 2025

We aim to refine the fundamental parameters of the TOI-2141 planetary system, which includes a transiting sub-Neptune orbiting a Sun-like star in a relatively long orbit of 18.26 days, by combining new photometric and spectroscopic observa…

The CHEOPS view of HD 95338b: Refined transit parameters, and a search for exomoons Open

Szilárd Kálmán, A. E. Simon, A. Deline, Sz. Csizmadia, M. Gy. Szabó , et al. · 2025

Context . Despite the ever-increasing number of known exoplanets, no uncontested detections have been made of their satellites, known as exomoons. Aims . The quest to find exomoons is at the forefront of exoplanetary sciences. Certain spac…

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

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

International audience

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…

Dark skies of the slightly eccentric WASP-18 b from its optical-to-infrared dayside emission Open

A. Deline, P. E. Cubillos, L. Carone, Brice-Olivier Demory, M. Lendl , et al. · 2025

Context . Ultra-hot Jupiters (UHJs) are gas giant exoplanets that are strongly irradiated by their star, setting intense molecular dissociation that leads to atmospheric chemistry dominated by ions and atoms. These conditions inhibit day-t…

Searching for hot water world candidates with CHEOPS Open

J.A. Egger, Daria Kubyshkina, Y. Alibert, H.P. Osborn, A. Bonfanti , et al. · 2025

Studying the composition of exoplanets is one of the most promising approaches to observationally constrain planet formation and evolution processes. However, this endeavour is complicated for small exoplanets by the fact that a wide range…

A joint effort to discover and characterize two resonant mini-Neptunes around TOI-1803 with TESS, HARPS-N, and CHEOPS Open

T. Zingales, L. Malavolta, L. Borsato, D. Turrini, A. Bonfanti , et al. · 2025

Context. The discovery and characterization of mini-Neptunes hold a potentially crucial impact on planetary formation and evolution theories. Estimating their orbital parameters and atmospheric properties would provide valuable hints to im…

Searching for Hot Water World Candidates with CHEOPS: Supplementary Material for TOI-238 b and TOI-1685 b (atmospheric evolution tracks) Open

J. A. Egger, Daria Kubyshkina, Y. Alibert, H. P. Osborn, A. Bonfanti , et al. · 2025

This distribution includes the supplementary data for sections 3.1.5 and 3.2.4 of Egger et al., 2025 (accepted for publication in A&A; https://arxiv.org/pdf/2502.07887), namely, the atmospheric evolution tracks of TOI-238 b and TOI-1685 b,…

Transit-timing variations in the AU Mic system observed with CHEOPS Open

Ádám Boldog, Gy. M. Szabó, L. Kriskovics, L. Borsato, D. Gandolfi , et al. · 2025

AU Mic is a very active M dwarf with an edge-on debris disk and two transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significant transit-timing variations (TTVs) that are caused by the g…

Transit-timing variations in the AU Mic system observed with CHEOPS Open

Ádám Boldog, M. Gy. Szabó, L. Kriskovics, L. Borsato, D. Gandolfi , et al. · 2025

Context . AU Mic is a very active M dwarf star with an edge-on debris disk and two known transiting sub-Neptunes with a possible third planetary companion. The two transiting planets exhibit significant transit-timing variations (TTVs) tha…

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

Allison 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-33b, 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…

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 joint effort to discover and characterize two resonant mini Neptunes around TOI-1803 with TESS, HARPS-N and CHEOPS Open

T. Zingales, L. Malavolta, L. Borsato, D. Turrini, A. Bonfanti , et al. · 2024

We present the discovery of two mini Neptunes near a 2:1 orbital resonance configuration orbiting the K0 star TOI-1803. We describe their orbital architecture in detail and suggest some possible formation and evolution scenarios. Using CHE…

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

Haochuan Yu, Z. Garai, M. Cretignier, Gy. 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…

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…

A close outer companion to the ultra-hot Jupiter TOI-2109 b? Open

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

Hot Jupiters 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, leading to the possible ejection of other planets. TOI-2109 b is…

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