85 citations · 717 across the 35 of their papers we have counts for
38 papers
Beyond Pebble Isolation: Diverse Pathways to Giant Planet Formation Across Stellar and Orbital Scales
Lorenzo Peerani, Sho Shibata, Ravit Helled
Context. Giant planet formation requires reaching crossover mass, i.e., when the mass of the gaseous envelope becomes equal to the mass of the core, within the disc's lifetime. The…
The metallicity of giant exoplanets around low-mass stars and how Ariel can help
Ravit Helled, Sho Shibata, Shubham Kanodia +1
Giant planets orbiting low-mass stars represent a unique population of giant planets that can be studied to constrain planet formation theory. Surveys of transiting giant exoplanet…
Composition gradients in sub-Neptunes: K2-18 b and TOI-270 d as case studies
Luca Morf, Ravit Helled
Structure models of sub-Neptunes commonly assume purely adiabatic interiors with distinct layers of homogeneous composition. We assess how allowing for more complex interiors with…
The MegaWave Radio Surveyor
T. Joseph W. Lazio, Evgenya Shkolnik, James Aguirre +40
Several Decadal-level questions in astrophysics, exoplanets, astrobiology, and cosmology can be addressed only at low radio frequencies inaccessible from Earth. The MegaWave Radio…
The atmospheric vertical structure of Uranus and Neptune from thermochemical models: the impact of model assumptions
Thomas Douçot, Ravit Helled, Daniel Kitzmann +2
The composition and temperature-pressure profile of the atmospheres of Uranus and Neptune are not well-determined. As observational data are limited, we often rely on chemical equi…
Evolutionary tracks of giant planets formed by disk instability
Mirco Bussmann, Ravit Helled
The evolution of giant planets depends on their formation history. While several evolutionary models self-consistently link planet formation by core accretion to long-term evolutio…
The influence of composition gradients on giant planet radii
Henrik Knierim, Ravit Helled
The radius of a giant planet is a key physical property. It encapsulates the outcome of its mass, composition, and thermal state, serving as a critical link between observations an…
Direct Measurement of Extinction in a Planet-Hosting Gap
G. Cugno, S. Facchini, F. Alarcon +12
Recent disk observations have revealed multiple indirect signatures of forming gas giant planets, but high-contrast imaging has rarely confirmed the presence of the suspected pertu…
On the origin of Jupiter's fuzzy core: constraints from N-body, impact and evolution simulations
Thomas Meier, Christian Reinhardt, Sho Shibata +3
It has been suggested that Jupiter's fuzzy core could be a result of a giant impact. Here, we investigate the expected impact conditions from N-body simulations. We then use state-…
The linear-mixing approximation in silica-water mixtures at planetary conditions
Valiantsin Darafeyeu, Stephanie Rimle, Guglielmo Mazzola +1
The Linear Mixing Approximation (LMA) is often used in planetary models for calculating the equations of state (EoSs) of mixtures. A commonly assumed planetary composition is a mix…
Convective Mixing in Gas Giant Planets with Primordial Composition Gradients
Henrik Knierim, Ravit Helled
Linking atmospheric measurements to the bulk planetary composition and ultimately the planetary origin is a key objective in planetary science. In this work, we identify the cases…
Discovery of a cold giant planet and mass measurement of a hot super-Earth in the multi-planetary system WASP-132
N. Grieves, F. Bouchy, D. J. Armstrong +25
Hot Jupiters generally do not have nearby planet companions, as they may have cleared out other planets during their inward migration from more distant orbits. This gives evidence…
Can Jupiter's atmospheric metallicity be different from the deep interior?
Simon Müller, Ravit Helled
Updated formation and structure models of Jupiter predict a metal-poor envelope. This is at odds with the two to three times solar metallicity measured by the Galileo probe. Additi…
The fuzzy cores of Jupiter and Saturn
Ravit Helled, David J. Stevenson
New interior models of Jupiter and Saturn suggest that both planets have "fuzzy cores". These cores should be viewed as central regions that are enriched with heavy elements but ar…
Searching for Giant Exoplanets around M-dwarf Stars (GEMS) I: Survey Motivation
Shubham Kanodia, Caleb I. Cañas, Suvrath Mahadevan +13
Recent discoveries of transiting giant exoplanets around M-dwarf stars (GEMS), aided by the all-sky coverage of TESS, are starting to stretch theories of planet formation through t…
Earth as an Exoplanet. III. Using Empirical Thermal Emission Spectra as an Input for Atmospheric Retrieval of an Earth-twin Exoplanet
Jean-Noël Mettler, Björn S. Konrad, Sascha P. Quanz +1
In this study, we treat Earth as an exoplanet and investigate our home planet by means of a potential future mid-infrared (MIR) space mission called the Large Interferometer For Ex…
An extended low-density atmosphere around the Jupiter-sized planet WASP-193 b
Khalid Barkaoui, Francisco J. Pozuelos, Coel Hellier +32
Gas giants transiting bright nearby stars provide crucial insights into planetary system formation and evolution mechanisms. Most of these planets exhibit certain average character…
Zonal winds of Uranus and Neptune: Gravitational harmonics, dynamic self-gravity, shape, and rotation
Deniz Soyuer, Benno Neuenschwander, Ravit Helled
Uranus and Neptune exhibit fast surface zonal winds that can reach up to few hundred meters per second. Previous studies on zonal gravitational harmonics and Ohmic dissipation cons…
Earth as an Exoplanet. II. Earth's Time-variable Thermal Emission and Its Atmospheric Seasonality of Bioindicators
Jean-Noel Mettler, Sascha P. Quanz, Ravit Helled +2
We assess the dependence of Earth's disk-integrated mid-infrared thermal emission spectrum on observation geometries and investigate which and how spectral features are impacted by…
Potential long-term habitable conditions on planets with primordial H-He atmospheres
Marit Mol Lous, Ravit Helled, Christoph Mordasini
Cold super-Earths which retain their primordial, H-He dominated atmosphere could have surfaces that are warm enough to host liquid water. This would be due to the collision induced…
Jupiter's Temperature Structure: A Reassessment of the Voyager Radio Occultation Measurements
Pranika Gupta, Sushil K. Atreya, Paul G. Steffes +12
The thermal structure of planetary atmospheres is an essential input for predicting and retrieving the distribution of gases and aerosols, as well as the bulk chemical abundances.…
Possible in situ formation of Uranus and Neptune via Pebble Accretion
Claudio Valletta, Ravit Helled
The origin of Uranus and Neptune is still unknown. In particular, it has been challenging for planet formation models to form the planets in their current radial distances within t…
Enrichment of Jupiter's atmosphere by late planetesimal bombardment
Sho Shibata, Ravit Helled
Jupiter's atmosphere is enriched with heavy elements by a factor of about 3 compared to proto-solar. The origin of this enrichment and whether it represent the bulk composition of…
A wide-orbit giant planet in the high-mass b Centauri binary system
Markus Janson, Raffaele Gratton, Laetitia Rodet +24
Planet formation occurs around a wide range of stellar masses and stellar system architectures. An improved understanding of the formation process can be achieved by studying it ac…