gas giant Archives

Planetary growth timescales in an irradiated disc

Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Icy Worlds, Status Report

Super-Earth Formation In Systems With Cold Giants

by Keith CowingJune 29, 2025June 28, 2025

Around our Sun, terrestrial planets did not grow beyond Earth in mass, while super-Earths are found to orbit approximately every other solar-like star.

Mass-Radius plot of asteroids, moons, planets, brown dwarfs and low-mass stars. From nearly 5600 exoplanets listed in the PHL-HWC database, 1504 are categorized as terrestrial worlds (orange dots), 2609 as Neptunian worlds (green dots), 1355 as Jovian worlds (purple dots), and 115 as brown dwarfs (brown dots). -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Nomenclature, Systematics, Natural History, Status Report

(Re)-Defining Planets — the Fundamental Plane of Planets

by Keith CowingJune 23, 2025June 23, 2025

6000+ exoplanets are now detected using various techniques, with estimates of billions of planets existing in our Galaxy alone.

Binary collision-induced H2–He absorption coefficient, α, normalized by the hydrogen and helium gas densities, as function of frequency in the fundamental band, at 296 K. The parato-ortho distribution, is representative of equilibrium H2, just as in Fig. 2. Our model (“this work”), is compared with the model of Abel et al.17 for T = 300K, and with the laboratory measurements of Vitali et al. 18 and Brodbeck et al.19 , both of which were made near 296 K. We note that neither our model nor that of Abel et al. considered the discrete, intercollisional interference dips present in the laboratory spectra. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Ice Giant, Jupiter, Neptune, Saturn, Status Report, Uranus

Improved H2-He and H2-H2 Collision-Induced Absorption Models and Application to Outer-Planet Atmospheres

by Keith CowingJune 15, 2025June 13, 2025

Using state-of-the-art ab initio interaction-induced dipole and potential-energy surfaces for hydrogen-helium (H2-He) pairs, we compute the rototranslational collision-induced absorption coefficient at 40-400 K for frequencies covering 0-4000 cm-1.

First direct image of 14 Her c. JWST/NIRCam coronagraphic imaging of the 14 Her system with the MASKA335R coronagraph (transmission indicated by gray shaded circles). North is up, east is left. Left: Prediction for the location of 14 Her c from a reproduction of the orbits presented in (G. F. Benedict et al. 2023), at the epoch of observation (MJD=60449), and the location of the point source detected in the F444W filter. Middle: A starlight-subtracted image taken with the F200W filter (1.755−2.227 µm), showing extended emission from a background galaxy at about 1. ′′5 to the SE from the host star. No other statistically significant point sources are apparent, as intended, given the cold temperature of the planet 14 Her c. Right: A starlight-subtracted image taken with the F444W filter (3.881−4.982 µm), showing extended emission from the same background galaxy, and a point source at 1. ′′1 to the SW with a contrast of 1 × 10−6 . The location of the point source, detected with a contrast of 9.6 × 10−7 , agrees within 1σ with the predicted location for the planet, so we conclude we have detected 14 Her c. -- (astro-ph.EP

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

JWST Coronagraphic Images of 14 Her c: a Cold Giant Planet in a Dynamically Hot, Multi-planet System

by Keith CowingJune 14, 2025June 12, 2025

Most observed multi-planet systems are coplanar, in a dynamically “cold” configuration of concentric orbits like our own Solar System.

Transit depth versus wavelength for our full atmosphere model of HD209458b (Model C). We zoom in past the extent of the Hα and He I 10830 ˚A line to show the comparison with HST observations (Sing et al. 2016) and JWST observations (with different data reduction pipelines in different colors) (Xue et al. 2024). The JWST observations analyzed can be accessed via DOI:10.17909/f5j3-jq48. Note that the Na D and K I lines are a result of only the lower/middle atmosphere model, and we do not calculate transit depths for these lines based on the upper atmosphere model. -- astro-ph.EP

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

A Multi-Species Atmospheric Escape Model with Excited Hydrogen and Helium: Application to HD209458b

by Keith CowingJune 13, 2025June 12, 2025

Atmospheric escape shapes exoplanet evolution and star-planet interactions, with He I 10830 Å absorption serving as a key tracer of mass loss in hot gas giants. However, transit depths vary […]

This image of exoplanet 14 Herculis c was taken by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera). A star symbol marks the location of the host star 14 Herculis, whose light has been blocked by a coronagraph on NIRCam (shown here as a dark circle outlined in white). NASA, ESA, CSA, STScI, W. Balmer (JHU), D. Bardalez Gagliuffi (Amherst College)

Astronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Icy Worlds, Press Release

Frigid Exoplanet 14 Herculis c Is In A Strange Orbit

by Keith CowingJune 12, 2025June 12, 2025

A planetary system described as abnormal, chaotic, and strange by researchers has come into clearer view with NASA’s James Webb Space Telescope. Using Webb’s NIRCam (Near-Infrared Camera), researchers have successfully […]

An artist’s illustration of solar system formation, and the formation of a protoplanetary disk filled with gases and dust that over time clump together and smash into each other to form larger and larger bodies. Image credit: Gemini Observatory/AURA/Lynette Cook.

Astrogeology, Exoplanets, -moons, -comets, Press Release

Space Pebbles And Rocks Played A Pivotal Role In A Giant Planet’s Formation

by Keith CowingJune 11, 2025September 18, 2025

Scientists analysing an ultra-hot giant planet believe it was formed by absorbing lightweight gases like methane evaporating from tiny space pebbles, whilst being bombarded with large rocky objects.

Close-up of the star RIK 113, seen here surrounded by a cloud of gas and dust called a protoplanetary disc. These discs are a common feature around young stars, containing all the building blocks needed to make a new planet. Over time, these dusty discs will fragment and condense under the influence of gravity, forming larger objects like protoplanets. These planetary embryos carve out gaps in the dust around them, forming the intricate, ring-like structures that we can see in this disc. -- ESO

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

RIK 113: The Likely Site Of A New Planet Forming

by Keith CowingJune 10, 2025June 10, 2025

An international team of astronomers led by University of Galway, has discovered the likely site of a new planet in formation, most likely a gas giant planet up to a […]

A summary schematic of assumptions that are made in planet formation modeling, protoplanetary disk modeling, and exoplanet atmospheric modeling. We note that several of the presented variables can be directly measured (e.g., planet mass, radius, and semi-major axis), but not necessarily in all systems. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Status Report

On Linking Planet Formation Models, Protoplanetary Disk Properties, and Mature Gas Giant Exoplanet Atmospheres

by Keith CowingJune 5, 2025June 5, 2025

Measuring a single elemental ratio (e.g., carbon-to-oxygen) provides insufficient information for understanding the formation mechanisms and evolution that affect our observations of gas giant planet atmospheres.

An artist’s rendering of the warm exoplanet WASP-80 b and an overview of its planet-system parameters. Planet image credit: NASA/Ames Research Center. astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report

A Precise Metallicity and Carbon-to-Oxygen Ratio for a Warm Giant Exoplanet from its Panchromatic JWST Emission Spectrum

by Keith CowingJune 5, 2025June 5, 2025

WASP-80 b, a warm sub-Jovian (equilibrium temperature ~820 K, 0.5 Jupiter masses), presents an opportunity to characterize a rare gas giant exoplanet around a low-mass star.

gas giant

Super-Earth Formation In Systems With Cold Giants

(Re)-Defining Planets — the Fundamental Plane of Planets

Improved H2-He and H2-H2 Collision-Induced Absorption Models and Application to Outer-Planet Atmospheres

JWST Coronagraphic Images of 14 Her c: a Cold Giant Planet in a Dynamically Hot, Multi-planet System

A Multi-Species Atmospheric Escape Model with Excited Hydrogen and Helium: Application to HD209458b

Frigid Exoplanet 14 Herculis c Is In A Strange Orbit

Space Pebbles And Rocks Played A Pivotal Role In A Giant Planet’s Formation

RIK 113: The Likely Site Of A New Planet Forming

On Linking Planet Formation Models, Protoplanetary Disk Properties, and Mature Gas Giant Exoplanet Atmospheres

A Precise Metallicity and Carbon-to-Oxygen Ratio for a Warm Giant Exoplanet from its Panchromatic JWST Emission Spectrum

How High-pressure Ices On Large Ocean Worlds Can Support Habitability: The Compatibility Of Amino Acids Into Ice VI And VII

Ice Drives The Emergence Of Functional Protocells

Chemical Abundance Patterns at z=1-7: Carbon, Nitrogen, Neon, Sulphur, and Argon Abundances From JWST Spectroscopy

Optimization of Petal-Shaped Occulters for Exo-Earth Observation

Topographically Forced Stationary Waves Can Explain The Near-Surface Zonal Winds Observed By Huygens On Titan