We report the discovery of two new exoplanet systems around fully convective stars, found from the radial-velocity (RV) variations of their host stars measured with the nIR spectropolarimeter CFHT/SPIRou over […]
sub-Neptune
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
HD 21520 b: A Warm Sub-Neptune Transiting A Bright G Dwarf
We report the discovery and validation of HD 21520 b, a transiting planet found with TESS and orbiting a bright G dwarf (V=9.2, Teff=5871±62 K, R⋆=1.04±0.02R⊙).
Posted inAstrochemistry, Astrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release
Small, Cool And Sulfurous Exoplanet May Help Write The Recipe For Planetary Formation
A surprising yellow haze of sulfur dioxide in the atmosphere of a gas “dwarf” exoplanet about 96 light years away from our own solar system makes the planet a prime […]
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
Sulfur Dioxide and Other Molecular Species in the Atmosphere of the Sub-Neptune GJ 3470 b
We report observations of the atmospheric transmission spectrum of the sub-Neptune exoplanet GJ 3470 b taken using the Near-Infrared Camera (NIRCam) on JWST. Combined with two archival HST/WFC3 transit observations […]
![Comparisons between the theoretical transmission spectra generated by EPACRIS (solid lines) and the JWST observations for (Top) H2:H2O=50:50 and [C+N+S]=100×solar metallicity scenario of K2-18 b assuming Ab = 0.3 corresponding to the left panel of Figure 4, and (Bottom) H2:H2O=75:25 and [C+N+S]=100×solar metallicity scenario of TOI-270 d assuming Ab = 0 corresponding to the right panel of Figure 4. The grey symbols with error bars indicate JWST observations of corresponding exoplanets taken from Madhusudhan et al. (2023) for K2-18 b (Top), and Benneke et al. (2024) for TOI-270 d (Bottom). Each color represents a spectrum generated by excluding specific species: green for no CH4, red for no CO2, light blue for no OCS, blue for no H2O, teal for no CO, light brown for no NH3, and black for all species included. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/06/Chemical-Mapping-of.png?resize=1200%2C720&ssl=1)
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
Chemical Mapping of Temperate Sub-Neptune Atmospheres: Constraining The Deep-interior H2O/H2 Using The Atmospheric CO2/CH4
Understanding the envelope composition of sub-Neptune-type exoplanets is challenging due to the inherent degeneracy in their interior composition scenarios. Particularly, the H2O/H2 ratio, or can be expressed as the O/H […]
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Press Release, Stellar Cartography, Water/Hycean Worlds & Oceanography
From Super-Earths to Sub-Neptunes: Observational Constraints and Connections to Theoretical Models
We update the PlanetS catalog of transiting planets with precise and robust mass and radius measurements and use this comprehensive catalog to explore Mass-Radius (M-R) diagrams.
![Mass–radius diagram of confirmed exoplanets with mass and radius precision better than 3σ and 10σ, respectively. Planetary parameters (black dots) are taken from the NASA Exoplanet Archive (https://exoplanetarchive.ipac.caltech.edu), and updated to October 2023. HD 73344b is represented by the red dot. The red arrow represents the upper 10σ limit on its mass. Composition models calculated from Aguichine et al. (2021) with a core mass fraction of 30% and various H2O mass fraction (from 10% to 80%) are represented by coloured lines (see text). Composition models calculated from Lopez & Fortney (2014) for a 1 Gyr-old system, Teq,b ∼ 900 K, and an envelope mass fraction fenv = [1, 2, 3, 4, 5] % are shown in gray. For comparison, the relation for an Earth-like composition (32.5% core, 67.5% mantle) from Brugger et al. (2017) is shown by the green dashed curve, and some solar system planets (Venus, the Earth, Uranus and Neptune) are displayed. -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/05/A-Low-mass-Sub-Neptune-Planet.png?resize=1200%2C719&ssl=1)
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report
A Low-mass Sub-Neptune Planet Transiting The Bright Active Star HD 73344
Context. Planets with radii of between 2-4 RE closely orbiting solar-type stars are of significant importance for studying the transition from rocky to giant planets.
Posted inAstrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Imaging & Spectroscopy, Status Report, Water/Hycean Worlds & Oceanography
The Discovery and Follow-up of Four Transiting Short-period Sub-Neptunes Orbiting M dwarfs
Sub-Neptunes with 2−3R⊕ are intermediate in size between rocky planets and Neptune-sized planets. The orbital properties and bulk compositions of transiting sub-Neptunes provide clues to the formation and evolution of […]
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
The TESS-Keck Survey. XXII. A sub-Neptune Orbiting TOI-1437
Exoplanet discoveries have revealed a dramatic diversity of planet sizes across a vast array of orbital architectures. Sub-Neptunes are of particular interest; due to their absence in our own solar […]
Posted inAstrogeology, Exoplanets, -moons, -comets, Status Report
How Planets Form by Pebble Accretion V. Silicate Rainout Delays Contraction of Sub-Neptunes
The characterization of Super-Earth-to-Neptune sized exoplanets relies heavily on our understanding of their formation and evolution.