Ariel mission Archives

Infographic of the OPAL campaign simulations in the ambit of the Ariel mission Dry Run of 2025. The green box contains the codes presented in this paper that make up the Arχes and the Exoclimes suites. We use as inputs provided homogenised information for the stellar and planetary samples and we produce the elemental bulk composition and the molecular atmospheric composition of these planets. These are used to make highly detailed and realistic synthetic atmospheric spectra. -- astro-ph.EP

Ariel Mission, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Missions & Hardware, Status Report, Stellar Cartography

The Origins Of Planets For ArieL (OPAL) Key Science Project: The End-to-end Planet Formation Campaign For The ESA Space Mission Ariel

by Keith CowingJanuary 26, 2026January 26, 2026

The growing body of atmospheric observations of exoplanets from space and ground-based facilities showcases how the great diversity of the planetary population is not limited to their physical properties but […]

Simulated stellar wind of TOI-1860, DS Tuc A, and HD 63433 in the x⋆ −y⋆ plane. The rotation axis lies along the positive z⋆. The Alfvén surface is shown as a translucent surface and its intersection on the x⋆ −y⋆ plane is shown as a white curve. The colour bar indicates the total wind velocity. The orbits of the hosted exoplanets are also included as coloured ellipses. For HD 63433, we also show the simulations from the 2023 data analysed in Bellotti et al. (2024). -- astro-ph.SR

Ariel Mission, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Missions & Hardware, Space Weather & Heliophysics, Status Report, Stellar Cartography

Spectropolarimetric Characterisation Of Exoplanet Host Stars In Preparation Of The Ariel Mission II. The magnetised wind environment of TOI-1860, DS Tuc A, and HD 63433

by Keith CowingDecember 27, 2025December 27, 2025

We update the status of the spectropolarimetric campaign dedicated to characterise the magnetic field properties of a sample of known exoplanet-hosting stars included in the current target list of the […]

Synoptic view of the key performances of the JWST’s instruments and Ariel for transiting exoplanets. Top table summarises the characteristics of instruments and observing modes for JWST. Central left panel: simulations of a WASP-39 b-like exoplanet, used as example of a relatively faint target (Vmag „ 12) optimal for various JWST’s instruments (NIRSpec, NIRISS, MIRI) and observable by Ariel in Tier 2. Bottom left panel: simulation of a HD189733 b-like exoplanet, used as example of a bright target (Vmag „ 7.7) observable with JWST NIRCam and optimal for Ariel in Tier 3. JWST’s noise is obtained with the ExoCTK Pandexo tool (Batalha et al., 2017), while the Ariel’s noise is estimated using the ArielRad simulator (Mugnai et al., 2020). -- astro-ph.IM

Ariel Mission, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

On The Synergetic Use Of Ariel And JWST For Exoplanet Atmospheric Science

by Keith CowingSeptember 9, 2025February 15, 2026

This white paper explores the potential for strategic synergies between the JWST and the Ariel telescopes, two flagship observatories poised to revolutionise the study of exoplanet atmospheres.

The radial gas temperature maps of planets from the 3D AFGKM ExoRad with a global temperature, Tglobal of 800K (left), 1600K (center) and 2400K (right) that orbit different host stars (top to bottom: A, G, M). The (Tgas, pgas)-maps gas are shown as equatorial slice plots. -- astro-ph.EP

AI - Data - Apps - Cybernetics, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Status Report

Accelerating Exoplanet Climate Modelling: A Machine Learning Approach To Complement 3D GCM Grid Simulations

by Keith CowingAugust 15, 2025August 15, 2025

With the development of ever-improving telescopes capable of observing exoplanet atmospheres in greater detail and number, there is a growing demand for enhanced 3D climate models to support and help […]

Suppression index Ξ as a function of mantle thermal gradient ∆T and bulk modulus K. Regions with Ξ > 1.1 (light-shaded) correspond to > 10% enhancements in escape velocity, indicating strong thermoelastic suppression of atmospheric loss. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report

Thermoelastic Contraction As A Suppressor Of Atmospheric Escape In Close-in Exoplanets

by Keith CowingAugust 12, 2025

The long-term retention of substantial atmospheres in close-in exoplanets presents a major challenge to classical hydrodynamic escape theory, which predicts rapid mass loss under intense stellar irradiation.

Multicolor simultaneous light curves in g-, r-, i-, and zs-bands, obtained by MuSCAT2 on 2021 March 19 (Top) and MuSCAT3 on 2021 January 28 (Bottom) (Section 2.2 and 2.3). The data are jointly fitted with the transit model (blue, green, orange, and red) and baseline model, and the data are subtracted with the baseline models (gray). Alt text: Time-series flux for the transits of the MuSCAT2 and MuSCAT3 data in g-, r-, i-, and zs-bands, and the optimum models for each. -- astro-ph.EP

Ariel Mission, Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

The Mass Of TOI-654 b: A Short-period Sub-Neptune Transiting A Mid-M Dwarf

by Keith CowingJuly 23, 2025July 23, 2025

Sub-Neptunes are small planets between the size of the Earth and Neptune. The orbital and bulk properties of transiting sub-Neptunes can provide clues for their formation and evolution of small […]

Potential interior structures of Uranus, Neptune, K2-18 b and TOI-270 d if they have undergone hydrogen-water demixing. We note that alternatives models are also possible (see Secs. 3 and 4). For Uranus and Neptune, the sketches correspond to the cases with Toffset = 1100 K, in which both planets are fully demixed. However, we can’t exclude scenarios in which demixing is still ongoing or does not occur at all. The sketch for K2-18 b shows a mini-Neptune scenario with ongoing demixing, while the one for TOI-270 d corresponds to a case of full demixing. -- astro-ph.EP

Ariel Mission, Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Ice Giant, Icy Worlds, Neptune, Status Report, Uranus

The Possibility of Hydrogen-Water Demixing in Uranus, Neptune, K2-18b and TOI-270d

by Keith CowingJuly 13, 2025July 13, 2025

The internal structures of Uranus and Neptune remain unknown. In addition, sub-Neptunes are now thought to be the most common type of exoplanets.

Number of planets observed in a notional 3 year Ariel transit survey. The white star highlights the best overall leverage. The one-room schoolhouse yields the most targets, with other scenarios resulting in 30–60% fewer planets. -- astro-ph.EP

Ariel Mission, Astronomy & Telescopes, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Maximizing Ariel’s Survey Leverage For Population-Level Studies Of Exoplanets

by Keith CowingJune 10, 2025June 10, 2025

ESA’s Ariel mission will be uniquely suited to performing population-level studies of exoplanets. Most of these studies consist of quantifying trends between an Ariel-measured quantity, y, and an a priori […]

The Rossiter-McLaughlin effect of WASP-129 Ab, WASP-162b, Qatar-7b, and EPIC 219388192b. The observed data points (black) are shown with their error bars. The systemic and Keplerian orbit velocities were removed. The blue line shows the best fitting model to the data, together with 1-σ (dark grey) and 3-σ (light grey) confidence intervals. -- astro-ph.EP

Ariel Mission, Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Ten Aligned Orbits: Planet Migration in the Era of JWST and Ariel

by Keith CowingMay 28, 2025May 28, 2025

Understanding the diverse formation and migration pathways that shape exoplanetary systems requires characterizing both their atmospheric properties and their orbital dynamics.

Overview of the proposed methodology. The workflow consists of a local data-centric pipeline including data pre-processing, feature engineering, and uncertainty-aware modeling. The trained model is then deployed on the Kaggle platform to perform inference and evaluation on the public and private challenge datasets. Insights from the public leader board and model evaluation are fed back into the pipeline (yellow arrow) to improve data processing and enhance model generalization in a data-centric approach. -- cs.LG

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Status Report

NeurIPS 2024 Ariel Data Challenge: Characterisation of Exoplanetary Atmospheres Using a Data-Centric Approach

by Keith CowingMay 21, 2025

The characterization of exoplanetary atmospheres through spectral analysis is a complex challenge. The NeurIPS 2024 Ariel Data Challenge, in collaboration with the European Space Agency’s (ESA) Ariel mission, provided an […]

Ariel mission

The Origins Of Planets For ArieL (OPAL) Key Science Project: The End-to-end Planet Formation Campaign For The ESA Space Mission Ariel

Spectropolarimetric Characterisation Of Exoplanet Host Stars In Preparation Of The Ariel Mission II. The magnetised wind environment of TOI-1860, DS Tuc A, and HD 63433

On The Synergetic Use Of Ariel And JWST For Exoplanet Atmospheric Science

Accelerating Exoplanet Climate Modelling: A Machine Learning Approach To Complement 3D GCM Grid Simulations

Thermoelastic Contraction As A Suppressor Of Atmospheric Escape In Close-in Exoplanets

The Mass Of TOI-654 b: A Short-period Sub-Neptune Transiting A Mid-M Dwarf

The Possibility of Hydrogen-Water Demixing in Uranus, Neptune, K2-18b and TOI-270d

Maximizing Ariel’s Survey Leverage For Population-Level Studies Of Exoplanets

Ten Aligned Orbits: Planet Migration in the Era of JWST and Ariel

NeurIPS 2024 Ariel Data Challenge: Characterisation of Exoplanetary Atmospheres Using a Data-Centric Approach

Ocean Planet Expeditions: Alvin Submersible Certified To Return To Service

Martian Dust Storms May Ggenerate Atmospheric Electrical Conditions That Could Impact Mars Missions

Discovery Of An Exterior Third Planet Orbiting β Pictoris

C,N,O,S, And Photochemistry In A Temperate Giant Planet Orbiting A Late M Dwarf

Coupled AtmospHere Interior modeL Intercomparison (CHILI). I. Evolutionary Modelling — Primordial Magma Oceans of Earth and Venus