radius valley Archives - Page 2 of 3 - Astrobiology

We present the discovery by the TESS mission of one transiting Neptune-sized planet, TOI-6223 b and two transiting super-Earths, TOI-1743 b and TOI-5799 b. We validate these planets using a statistical validation method, multi-color light curves and other ancillary observations. astro-ph.EP

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

TOI-1743 b, TOI-5799 b, TOI-5799 c and TOI-6223 b: TESS Discovery And Validation Of Four Super-Earth To Neptune-sized Planets Around M dwarfs

by Keith CowingSeptember 19, 2025September 19, 2025

We combined TESS and ground-based photometric data to constrain the physical properties of the planets. TOI-6223-b is slightly larger than Neptune (Rp=5.12+0.24−0.25 R⊕) orbiting an early M dwarf in 3.86 […]

The upper panel illustrates the mass loss processes and potential formation of graphite in sub-Neptune atmospheres within the graphitestability regime. The lower panel presents the atmospheric compositions calculated from the thermochemical equilibrium model without and with graphite. -- astro-ph.EP

Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

Formation Of Organic Hazes In CO2-rich Sub-Neptune Atmospheres Within The Graphite-stability Regime

by Keith CowingAugust 13, 2025August 13, 2025

Super-Earths and sub-Neptunes are the most common exoplanets, with a “radius valley” suggesting that super-Earths may form by shedding sub-Neptunes’ gaseous envelopes.

GMM fits to the unbinned radius data, along with corresponding histograms, are presented for the entire low-mass star sample and for M, K, and G stellar types. The Super-Earth and Mini-Neptune peaks, as well as the radius valley, are indicated in each plot. -- astro-ph.EP

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

Radius Valley Scaling Among Low Mass Stars With TESS

by Keith CowingJuly 11, 2025July 11, 2025

The Transiting Exoplanet Survey Satellite (TESS) has been highly successful in detecting planets in close orbits around low-mass stars, particularly M dwarfs.

Injection-and-recovery experiment performed to test the detectability of extra planets in the system using the tow TESS sectors described in Sect 5.3. The red star marks the position of TOI-1846 b - astro-ph.EP

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

TOI-1846b: A super-Earth In The Radius Valley Orbiting A Nearby M dwarf

by Keith CowingJune 24, 2025June 24, 2025

We present the discovery and validation of a super-Earth planet orbiting the M dwarf star TOI-1846 (TIC 198385543).

Nearby sources contaminating the TOI-1117 photometry. Left: TPF-shaped heatmap with the pixel-by-pixel flux fraction from TOI-1117 in S13. The red grid is the SPOC aperture. The pixel scale is 21 arcsec pixel−1 . The white disks represent all the Gaia sources, and the five sources that most contribute to the aperture flux are highlighted in different colours. The disk areas scale with the emitted fluxes. Right: Flux contributions to the SPOC aperture from the target and most contaminant stars. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report

The TOI-1117 Multi-planetary System: 3 Sub-Neptunes, 1 In Both The Neptunian Desert And Radius Valley

by Keith CowingJune 9, 2025September 18, 2025

We present the discovery of three sub-Neptune planets around TOI-1117, a Sun-like star with mass 0.97±0.02M⊙, radius 1.05±0.03R⊙, age 4.42±1.50 Gyr and effective temperature 5635±62 K. Light curves from TESS […]

Atmospheric composition trends for planets around M stars after 5 Gyr.

Astrochemistry, Astrogeology, Atmospheres, Climate, Weather, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

An Oxidation Gradient Straddling the Small Planet Radius Valley

by Keith CowingMarch 12, 2025March 12, 2025

We present a population-level view of volatile gas species (H2, He, H2O, O2, CO, CO2, CH4) distribution during the sub-Neptune to rocky planet transition, revealing in detail the dynamic nature […]

Top row: Final semi-major axes and planet masses for the planet population after disc dissipation. The color denotes the final atmosphere mass fraction. The dashed lines show the pebble isolation mass at the start and end of the disc lifetime; the variation is due to the temporal change of the stellar luminosity. Bottom row: Atmosphere mass fraction as a function of core masses. The colors of the points show the injection location in the disc. In the left column we show the the population when gas accretion at the inner edge is halted. In the middle column we show the population when gas accretion continues at the inner edge while in the right column we show the planet population when we vary the inner edge. In general, atmosphere mass fractions for massive cores are similar in all three models. If gas accretion is halted at the inner edge, atmosphere mass fractions are low (up to ∼0.1-5%) due to the efficient migration happening in the disc. When gas accretion continues at the inner edge, the atmosphere mass fractions of the smallest cores can reach up to 1%. Finally, when varying the inner edge, planets that are accreting gas further away from the star are able to accrete more gas due to more efficient contraction, reaching atmosphere mass fractions of almost ∼10%. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography, Water/Hycean Worlds & Oceanography

A Primordial Radius Valley As A Consequence Of Planet Formation

by Keith CowingFebruary 18, 2025

The radius distribution of close-in planets has been observed to have a bimodal distribution with a dearth of planets around ~1.5-2.0 R⊕ commonly referred to as the ”radius valley”.

Snapshots show planetary seeds’ growth and migration from two rings of material. This simulation comes from our M6T2 scenario. The top-left panel shows the starting time of the simulation. The time of each snapshot is shown on the bottom-left of each panel. The color of each dot corresponds to the water mass fraction of each planetary seed. We plot planetesimal and pebble isolation masses with dotted and dashed lines, respectively. The planetesimal isolation mass is obtained by extrapolating the initial surface density of the inner planetesimal disk. The vertical blue dashed line shows the location of the water condensation line. The blue solid line is the boundary of the inward and outward migration where the migration torque is zero. -- astro-ph.EP

Exoplanets, -moons, -comets, Habitable Zones, Icy Worlds, Status Report, Water/Hycean Worlds & Oceanography

Formation of Super-Earths and Mini-Neptunes From Rings of Planetesimals

by Keith CowingJanuary 8, 2025

The solar system planetary architecture has been proposed to be consistent with the terrestrial and giant planets forming from material rings at ~1 au and ~5 au, respectively.

NIR AO imaging and sensitivity curve for TOI 5713 (Keck) and TOI 6002 (Palomar). Inset: Images of the central portion of the data. -- astro-ph.EP

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

TESS Discovery of Two Super-Earths Orbiting the M-dwarf Stars TOI-6002 and TOI-5713 Near The Radius Valley

by Keith CowingSeptember 17, 2024September 17, 2024

We present the validation of two TESS super-Earth candidates transiting the mid-M dwarfs TOI-6002 and TOI-5713 every 10.90 and 10.44 days, respectively.

NIR AO imaging and sensitivity curve for TOI 5713 (Keck) and TOI 6002 (Palomar). Inset: Images of the central portion of the data. -- astro-ph.EP

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

TESS Discovery of Two Super-Earths Orbiting the M-dwarf Stars TOI-6002 and TOI-5713 Near The Radius Valley

by Keith CowingAugust 10, 2024August 10, 2024

We present the validation of two TESS super-Earth candidates transiting the mid-M dwarfs TOI-6002 and TOI-5713 every 10.90 and 10.44 days, respectively. The first star (TOI-6002) is located 32.038±0.019 pc […]