CHEOPS Archives

Artist's impression of the planetary system around the star LHS 1903. Credit: ESA

Exoplanets, -moons, -comets, Gas Giants, Press Release, Stellar Cartography

Study Reveals A Planetary System With An Unexpected Rocky Planet In Its Outer Region

by Keith CowingFebruary 16, 2026February 16, 2026

An international scientific team, led by the University of Warwick and involving the Canary Islands Institute of Astrophysics, has used the European Space Agency’s Cheops satellite to discover that the […]

Cheops open questions: How do planets form?

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Press Release, Stellar Cartography

Cheops Discovers Late Bloomer Planet From Another Era

by Keith CowingFebruary 13, 2026February 13, 2026

Many Vile Earthlings Munch Jam Sandwiches Under Newspapers and My Very Educated Mother Just Served Us Nachos. What sounds like gibberish half-sentences are memory aids taught to children to help […]

Artist's concept of exoplanet candidate HD 137010 b, dubbed a "cold Earth" because it's a possible rocky planet slightly larger than Earth, orbiting a Sun-like star about 146 light-years away. NASA/JPL-Caltech/Keith Miller (Caltech/IPAC)

Analog Studies, Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Press Release

Exoplanet Candidate HD 137010 b: An Ice-Cold Earth Analog?

by Keith CowingJanuary 30, 2026January 30, 2026

The Discovery A candidate planet that might be remarkably similar to Earth, HD 137010 b, has one potentially big difference: It could be colder than perpetually frozen Mars. See A […]

Stability analysis of the TOI-5788 planetary system. For fixed initial conditions (Table 4), the parameter space of the system is explored by varying the orbital period and the eccentricity of planet c (left panel) and the eccentricities of both planets (right panel). The step size is 0.0025 in the eccentricities, 0.001 d in the orbital period of planet b, and 0.003 d in the orbital period of planet c. For each initial condition, the system is integrated over 5000 yr and, from a frequency analysis of the mean longitude of the outer planet, a stability indicator is calculated. The colours in the plot represent the chaotic diffusion, measured by the variation in the frequency (see text). Red points correspond to highly unstable orbits, whilst blue points correspond to orbits which are likely to be stable on Gyr timescales. The black dots show the values of the best fit solution (Table 4). -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report, Stellar Cartography, Water/Hycean Worlds & Oceanography

Discovery and Characterisation of Two Exoplanets Orbiting the Metal-poor, Solar-type Star TOI-5788 with TESS, CHEOPS, and HARPS-N

by Keith CowingJanuary 28, 2026January 28, 2026

We present the discovery and characterisation of two transiting exoplanets orbiting the metal-poor, solar-type star TOI-5788.

Stability analysis of the TOI-6041 system. The phase space of the system is explored by varying the orbital period Pi and eccentricity ei of each planet independently. For each initial condition (Table 4), the system is integrated over 10 kyr, and a stability criterion is derived with the frequency analysis of the mean longitude. The chaotic diffusion is measured by the variation in the frequencies. The color scale corresponds to the logarithmic variation in the stability index used in (Correia et al. 2010). The red zone corresponds to highly unstable orbits, while the dark blue region can be assumed to be stable on a billion-year timescale. White dashed lines indicate the nominal orbital periods reported in Table 4. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report

Giant Outer Transiting Exoplanet Mass (GOTEM) Survey.VII. TOI-6041: A Multi-planet System Including A Warm Neptune Exhibiting Strong TTVs

by Keith CowingDecember 28, 2025December 28, 2025

We present the characterization of the TOI-6041 system, a bright (V=9.84±0.03) G7-type star hosting at least two planets.

Photometric 2-minute cadence PDCSAP time series of TIC 4897275 (HD 85426) in TESS sectors 21 (top panel) and 48 (bottom panel) are shown in grey, with 30-minute binned data overlaid in black. The transits of HD 85426 b are indicated by the blue box transits. The rise in flux shortly after BJD 2,459,630 is caused by a passing asteroid. The predicted conjunction time windows for planet c and planet candidate d are shaded in orange and violet, respectively. The width of these conjunction time windows was set to twice the predicted uncertainty.-- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Status Report

HARPS-N, TESS, and CHEOPS Discover A Transiting Sub-Neptune And Two Outer Companions Around The Bright Solar Analogue HD 85426

by Keith CowingNovember 14, 2025November 15, 2025

We provide a detailed characterisation of the planetary system orbiting HD 85426 (TOI-1774).

WASP-39b 3D model cross sections. Shown are the local gas temperature, Tgas [K] (left) and cloud dust-to-gas mass ratio, ρdust/ρgas (right). The values are derived from the 3D GCM results and shown as cross section across the evening (left hemisphere) and morning terminator (right hemisphere). -- astro-ph.EP

Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Exoplanet Climate Characterization With Transit Asymmetries — A Comprehensive Population Study From The Optical To The Infrared

by Keith CowingNovember 10, 2025November 10, 2025

Space missions (CHEOPS, JWST, PLATO) facilitate detailed characterization of exoplanets. This work provides a framework to characterize cloud and climate properties of close-in gas giants via transit depth asymmetries from […]

Phase folded transits of TOI-2345 b (purple) and TOI-2345 c (green) with the best-fit model from the joint fit in juliet in the top panel. The bottom panel shows the residuals. Left: TESS data. Right: CHEOPS data. -- astro-ph.EP

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

An Ultra-Short Period Super-Earth and Sub-Neptune Spanning the Radius Valley Orbiting the Kinematic Thick Disk Star TOI-2345

by Keith CowingOctober 16, 2025October 16, 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 […]

Stability analysis of the TOI-1203 system in the orbital period-eccentricity domain: planet b (top left), c (top right), d (bottom left), and e (bottom right). For fixed initial conditions, the phase space of the system is explored by varying the orbital period Pi and eccentricity ei of each planet independently. For each initial condition, the system is integrated over 40 kyr, and a stability criterion is derived with the frequency analysis of the mean longitude. The chaotic diffusion is measured by the variation in the frequencies and the color scale corresponds to the decimal logarithm of the stability index D. The red zone corresponds to highly unstable orbits, while the dark blue region can be assumed to be stable on a billion-year timescale. The current positions of the planets are marked with circles in each plot, and error bars represent the observational uncertainties (Tables B.2 and B.3). The white dashed vertical lines correspond to the main MMRs in the system. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release

A Four-planet System Orbiting The Old Thick Disk Star TOI-1203

by Keith CowingSeptember 17, 2025September 17, 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.

Transit light curves and fits for HD 60779 b. The transit models were all fit simultaneously with the RVs, details listed in Table 2. The upper left panel shows the flattened 120 s cadence data from TESS Sector 34. This is the original transit detection. The lower left panel shows the flattened 20 s cadence data from TESS Sector 88. The upper right panel shows the CHEOPS light curve, with the detrending model plotted. The lower right panel shows the detrended CHEOPS transit light curve, fit with the transit model. In all panels, the black points show the data in bins of 0.025 d. -- astro-ph.EP

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Press Release

The HD 60779 Planetary System: A Transiting Sub-Neptune On A 30-day Orbit And A More Massive Outer World

by Keith CowingAugust 28, 2025August 28, 2025

We present the discovery of the planetary system orbiting the bright (V = 7.2), nearby (35 pc), Sun-like star HD 60779, which has a mass of 1.050 +/- 0.044 solar […]

CHEOPS

Study Reveals A Planetary System With An Unexpected Rocky Planet In Its Outer Region

Cheops Discovers Late Bloomer Planet From Another Era

Exoplanet Candidate HD 137010 b: An Ice-Cold Earth Analog?

Discovery and Characterisation of Two Exoplanets Orbiting the Metal-poor, Solar-type Star TOI-5788 with TESS, CHEOPS, and HARPS-N

Giant Outer Transiting Exoplanet Mass (GOTEM) Survey.VII. TOI-6041: A Multi-planet System Including A Warm Neptune Exhibiting Strong TTVs

HARPS-N, TESS, and CHEOPS Discover A Transiting Sub-Neptune And Two Outer Companions Around The Bright Solar Analogue HD 85426

Exoplanet Climate Characterization With Transit Asymmetries — A Comprehensive Population Study From The Optical To The Infrared

An Ultra-Short Period Super-Earth and Sub-Neptune Spanning the Radius Valley Orbiting the Kinematic Thick Disk Star TOI-2345

A Four-planet System Orbiting The Old Thick Disk Star TOI-1203

The HD 60779 Planetary System: A Transiting Sub-Neptune On A 30-day Orbit And A More Massive Outer World

Astrobiologist Dale Andersen’s Antarctic Field Report: 9 November 2026: Lake Untersee Basecamp Update

From Anoxic to Oxic Earth: Detectability of Atmospheric Biosignatures Across Stellar Hosts with ELT/ANDES

The Kinetic Basis of the Genetic Code

Power Density as a Universal Biosignature: An Application to the Stellivore Hypothesis

The Limits of Tidal Circularization and Atmospheric Escape for Mini-Neptunes and Super-Earths: The Case of TOI-2257 b