radius valley Archives - Page 3 of 3 - Astrobiology

TESS target pixel files for TOI-260 for sector 3 (left), and for TOI-286 for sector 1 ( right). The remaining sectors are shown in Appendix A. The target star is labelled as 1 and marked by a white cross in each case. All sources from the Gaia DR3 catalogue down to a magnitude contrast of 8 are shown as red circles, with the size proportional to the contrast. The SPOC pipeline aperture is overplotted in shaded red squares. -- astro-ph.EP

Habitable Zones, Status Report, Water/Hycean Worlds & Oceanography

Three Super-Earths And A Possible Water World From TESS And ESPRESSO

by Keith CowingJune 12, 2024June 12, 2024

Since 2018, the ESPRESSO spectrograph at the VLT has been hunting for planets in the Southern skies via the RV method. One of its goals is to follow up candidate […]

Mass-Radius Diagram comparing the data from the PlanetS catalog and the data from NASA Exoplanet Archive to highlight the effects of our selection criteria and our detailed study of references. The grey dots represented the default parameters from NASA, the light blue triangles the same but filtered with our criteria on uncertainties and the blue dots correspond to the PlanetS catalog. The resulting M-R relationships from Sect.2.2 are in solid red lines with the confidence intervals represented by the shaded red areas. The transitions between the three populations are represented by the composition line of 20% water at 650 K from Luo et al. (2024) in dashed orange and the dotted black line at 138 M⊕. -- astro-ph.EP

Astronomy & 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

by Keith CowingJune 7, 2024June 7, 2024

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.

Eccentricity distribution of planets with measured radii of 1.5 − 4R⊕ and orbital periods of ≲ 50 days around M dwarfs with Teff = 3000 − 3900 K. Only planets with measured eccentricities are shown. The color contour represents the effective temperature of a planet-hosting M dwarf. The four close-in, sub-Neptunes validated in this study are shown as red stars. astro-ph.EP

Astrogeology, 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

by Keith CowingMay 22, 2024May 22, 2024

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 […]

Radius valley fit as a function of the stellar mass (blue line with errors in light-blue) for all our synthetic planets (colour-coded as a function of the water mass fraction). Dots correspond to the nominal output, diamonds to collisions. The green dashed line with the light-green shaded area show the best fit found by Petigura et al. (2022), the violet dashed line and the lilac shaded area represent the results found by Berger et al. (2020), and the mustard dashed line and the light-mustard shaded area represents the best fit by Luque & Pallé (2022). Our best fit was found using gapfit(Loyd et al. 2020). -- astro-ph.EP

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

A Fading Radius Valley Towards M-dwarfs, A Persistent Density Valley Across Stellar Types

by Keith CowingApril 3, 2024April 3, 2024

The radius valley separating super-Earths from mini-Neptunes is a fundamental benchmark for theories of planet formation and evolution. Observations show that the location of the radius valley decreases with decreasing […]

We show the transmission spectrum for each reduction in the top panel and the differences between the reductions (in units of sigma) in the bottom panel. All three of our reductions agree per-point, at the ∼2σ level or better, with a median difference of 6ppm. -- astro-ph.EP

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

JWST COMPASS: A NIRSpec/G395H Transmission Spectrum Of The Sub-Neptune TOI-836c

by Keith CowingApril 2, 2024

Planets between the sizes of Earth and Neptune are the most common in the Galaxy, bridging the gap between the terrestrial and giant planets in our Solar System.

Artistic representation of an exoplanet whose water ice on the surface is increasingly vaporizing and forming an atmosphere during its approach to the central star of the planetary system. This process increases the measured planetary radius compared to the value the planet would have at its place of origin. CREDIT Thomas Müller (MPIA)

Astronomy & Telescopes, Exoplanets, -moons, -comets, Gas Giants, Press Release, Water/Hycean Worlds & Oceanography

Migration Solves An Exoplanet Puzzle

by Keith CowingFebruary 9, 2024February 9, 2024

Ordinarily, planets in evolved planetary systems, such as the Solar System, follow stable orbits around their central star. However, many indications suggest that some planets might depart from their birthplaces […]

Radius histograms of synthetic planets with orbital periods shorter than 100 days for different model assumptions without any bias applied. For each panel, the full distribution is shown in gray and colored histograms are showing different compositional subsets (pure rocky in green, water-rich without any H/He in blue, with some H/He in red). The left panel shows the nominal model, in the middle panel water was assumed to be condensed out in a solid ice layer resistant to evaporation below H/He, and the right panel uses the nominal treatment of water but excludes evaporation. The dotted histogram shows the full distribution from the nominal simulations. As in Fig. 1, bin counts are normalized by the total number of planets in the different samples. -- astro-ph.EP

Astrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Exoplanets, -moons, -comets, Status Report

A Radius Valley Between Migrated Steam Worlds And Evaporated Rocky Cores

by Keith CowingJanuary 11, 2024January 10, 2024

The radius valley (or gap) in the observed distribution of exoplanet radii, which separates smaller super-Earths from larger sub-Neptunes, is a key feature that theoretical models must explain. Conventionally, it […]