sub-Neptune Archives

(a) Temporal evolution of the gas surface density. Different lines indicate disks with different αrϕ parameter. (b) Migration map for the disk with αrϕ = 10−4 at t = 1 Myr. The colors indicate the direction of migration, with red indicating outward migration and blue inward migration. The solid line shows the zero migration curve, which separates the regions of inward and outward migration. Note that the map depends on the eccentricity and inclination, which are set to 0.005.

Super-Earth Formation With Slow migration From A Ring In An Evolving Peaked Disk Compatible With Terrestrial Planet Formation

by Keith CowingJuly 25, 2024July 25, 2024

For the origin of the radially concentrated solar system’s terrestrial planets, planet formation from a ring of solids at about 1 au from the Sun with convergent/suppressed type I migration […]

Planetary properties for the combined sample used for analysis and probability density distribution split by planet radius or period. Left: Planetary radius and orbital period for all the known transiting planets associated with the 153 planet hosts in Louden et al. (2021) and the 20 planet hosts in the 2022 sample are shown on top of the full KOI sample. The planets outlined in black have hosts with Teff > 6250 K. Right: We divided the planets into subsets based on radius and period and fit the sub-samples. The dashed lines on the left panel show the locations of the cuts over the planet sample in period-radius space. After performing each of the two cuts, the resulting distributions of ⟨sin i⟩ are labeled according to the half they represent. -- astro-ph.EP

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

A Larger Sample Confirms Small Planets Around Hot Stars Are Misaligned

by Keith CowingJuly 1, 2024July 1, 2024

The distribution of stellar obliquities provides critical insight into the formation and evolution pathways of exoplanets. In the past decade, it was found that hot stars hosting hot Jupiters are […]

Detrended TESS (top row) and CHEOPS (bottom row) light curves, phase-folded to the orbital periods of HIP 29442 b (left), c (middle) and d (right). The coloured points show the 30-min binned data, the solid black lines show the best-fit transit models. -- astro-ph.EP

Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gas Giants, Icy Worlds, Imaging & Spectroscopy, Press Release, Water/Hycean Worlds & Oceanography

Unveiling the Internal Structure And Formation History Of The Three Planets Transiting HIP 29442 (TOI-469) With CHEOPS

by Keith CowingJune 28, 2024June 28, 2024

Multiplanetary systems spanning the radius valley are ideal testing grounds for exploring the proposed explanations for the observed bimodality in the radius distribution of close-in exoplanets. One such system is […]

Full sample of 133 sub-Neptunes used in this study. The top-left panel shows the mass-radius relation. The (nearly)-resonant population is defined as ∆MMR 0.05. The black line is the sub-Neptune mass-radius relation from Parc et al. (2024). Other panels show the cumulative distributions for parameters of the planets or their host star. The pvalue given for each parameter is the probability that the distribution of that parameter is drawn form the same underlying distribution for the (nearly) resonant and non-resonant populations. The potential 2D correlation between parameters is explored in Fig. B.1. -- astro-ph.EP

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

Resonant Sub-Neptunes Are Puffier

by Keith CowingJune 28, 2024June 28, 2024

A systematic, population-level discrepancy exists between the densities of exoplanets whose masses have been measured with transit timing variations (TTVs) versus those measured with radial velocities (RVs).

Radius versus Teff for all observed systems, showing both initial Kepler values from DR25 (magenta points; Berger et al. 2018) and the revised primary star values from this work (navy points), with the initial and revised values for each system connected by a black line. The underlying curves are MIST isochrones at various ages. The lower panel indicates the percent residual between the 1 Gyr evolutionary model and the final primary star radius for accepted systems. -- astro-ph.EP

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

Revising Properties of Planet-Host Binary Systems. IV. The Radius Distribution of Small Planets in Binary Star Systems is Dependent on Stellar Separation

by Keith CowingJune 26, 2024June 26, 2024

Small planets (Rp≤4R⊕) are divided into rocky super-Earths and gaseous sub-Neptunes separated by a radius gap, but the mechanisms that produce these distinct planet populations remain unclear.

The transmission spectrum of the sub-Neptune K2-18 b, a candidate Hycean world (from Madhusudhan et al. 2023). The observed JWST spectrum is shown in the orange and red data obtained with the NIRISS and NIRSpec instruments on JWST as noted in the legend. The dark blue line denotes the median-fit model spectrum while medium and lighter blue regions denote the 1σ and 2σ contours, respectively. CH4 and CO2 are detected robustly at 5σ and 3σ confidence, respectively, as evident from their strong spectral features labelled in the figure. Only marginal evidence for DMS is found in regions of the spectrum overlapping with the strong CH4 and CO2 features as shown. The yellow circles show the median-fit model binned to the same resolution as the data. -- astro-ph.EP

Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Origin & Evolution of Life, Status Report, Water/Hycean Worlds & Oceanography

The Hycean Paradigm in the Search for Life Elsewhere

by Keith CowingJune 19, 2024June 19, 2024

The search for habitable conditions and signs of life on exoplanets is a major frontier in modern astronomy. Detecting atmospheric signatures of Earth-like exoplanets is challenging due to their small […]

Reconstructed maps of the large-scale field of GJ 3378 -- astro-ph.EP

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

Characterizing Planetary Systems With SPIRou: A Temperate Sub-Neptune Exoplanet Orbiting The Nearby Fully-convective Star GJ 1289 And A Candidate Around GJ 3378

by Keith CowingJune 18, 2024

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 […]

Phase folded TESS transit data with modeled allesfitter fit (grey), and residuals plot on the bottom. Also plotted are the phase folded points binned to 30 minutes (black). -- astro-ph.EP

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

HD 21520 b: A Warm Sub-Neptune Transiting A Bright G Dwarf

by Keith CowingJune 17, 2024June 17, 2024

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⊙).

The sulfur-laden atmosphere discovered on gaseous exoplanet GJ 3470 b, show here in an illustration orbiting its star in the constellation Cancer, could help researchers figure out how it (and similar planets) were formed. Image: Department of Astronomy, UW–Madison

Astrochemistry, 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

by Keith CowingJune 11, 2024June 11, 2024

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 […]

Three independent reductions of the NIRCam F322W2 and F444W data agree within their uncertainties The top panel shows the F322W2 and F444W transmission spectra, as reduced using the Pegasus, Eureka, and tshirt pipelines, plotted with their associated 1 σ uncertainties using constant 0.015µm-wide spectral bins. All of the F322W2 spectra have been offset down by 163 ppm to correct for a bias offset in the F322W2 transit depths compared to the F444W and Spitzer data (see Appendix B.3). All three reductions agree on the shape of the transmission spectrum and show features due to H2O (2.5–3.2µm), CH4 (3.2–3.5µm), SO2 (3.9–4.1µm), and CO2 (2.6–2.9µm and 4.2–4.5µm). The absorption cross sections of the prominent species in this wavelength range, many of which are visually identifiable in the bottom panel. -- astro-ph.EP

Astronomy & 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

by Keith CowingJune 11, 2024June 11, 2024

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 […]

sub-Neptune

Super-Earth Formation With Slow migration From A Ring In An Evolving Peaked Disk Compatible With Terrestrial Planet Formation

A Larger Sample Confirms Small Planets Around Hot Stars Are Misaligned

Unveiling the Internal Structure And Formation History Of The Three Planets Transiting HIP 29442 (TOI-469) With CHEOPS

Resonant Sub-Neptunes Are Puffier

Revising Properties of Planet-Host Binary Systems. IV. The Radius Distribution of Small Planets in Binary Star Systems is Dependent on Stellar Separation

The Hycean Paradigm in the Search for Life Elsewhere

Characterizing Planetary Systems With SPIRou: A Temperate Sub-Neptune Exoplanet Orbiting The Nearby Fully-convective Star GJ 1289 And A Candidate Around GJ 3378

HD 21520 b: A Warm Sub-Neptune Transiting A Bright G Dwarf

Sulfur Dioxide and Other Molecular Species in the Atmosphere of the Sub-Neptune GJ 3470 b

Miraflores Butte On Mars

Ocean World Exploration: 2026 American Samoa ROV + Mapping Exploration

Development Of An Adaptive Optics Testbed At MPIA For The ELT/Planetary Camera And Spectrograph (PCS)

Exploring Long-period Architectures: Four New Planet Candidates from Kepler with Periods >342 days

The Selfish Ribosome