The Kepler and K2 missions enabled robust calculations of planet occurrence rates around FGKM-type stars. However, these missions observed too few stars with earlier spectral types to tightly constrain the […]
K2
![Super-Earth occurrence for Kepler (black circles) and K2 (gray circles), TESS data assuming all candidates are real (teal square), and 99.7% confidence intervals to calculate the upper limits for TESS data assuming all candidates are false positives (teal triangles) as a function of metallicity. The [-0.25,-0.5] bin occurrence rates are offset horizontally for visual clarity. The best-fit power-law trend line for the Kepler and K2 data (yellow) is displayed and extrapolated to [Fe/H]= -0.75 showing the 1-σ uncertainties (Zink et al. 2023). We show the combined best-fit exponential trend line for Kepler, K2, and TESS (purple) (eq. 6) including the 1-σ uncertainties. Each metallicity bin is indicated by gray dashed lines. Within the [-0.75,-1] bin, there is insufficient data to further constrain the super-Earth occurrence rate as a function of metallicity (denoted by the gray hatched region). -- astro-ph.EP](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/07/The-First-Evidence-of-a-Host.png?resize=1200%2C720&ssl=1)
Posted inAstrochemistry, Astrogeology, Exoplanets, -moons, -comets, Press Release
The First Evidence of a Host Star Metallicity Cut-off In The Formation of Super-Earth Planets
Planet formation is expected to be severely limited in disks of low metallicity, owing to both the small solid mass reservoir and the low opacity accelerating the disk gas dissipation.
![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 inAstrochemistry, Astrogeology, Astronomy & Telescopes, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report
Stellar Characterization and a Chromospheric Activity Analysis of a K2 Sample of Planet-Hosting Stars
Effective temperatures, surface gravities, and iron abundances were derived for 109 stars observed by the K2 mission using equivalent width measurements of Fe I and Fe II lines. Calculations were […]
Posted inAstronomy & Telescopes, Habitable Zones, Status Report
Long-term Stellar Activity Of M dwarfs: A Combined K2 And TESS Study Of Two Early M-type Stars
Studies of the rotation and activity of M type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution.
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Status Report, Stellar Cartography
Differences Between Stable and Unstable Architectures of Compact Planetary Systems
We present a stability analysis of a large set of simulated planetary systems of three or more planets based on architectures of multiplanet systems discovered by Kepler and K2.
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report, Stellar Cartography
Metallicities and Refined Stellar Parameters for 52 Cool Dwarfs with Transiting Planets and Planet Candidates
We collected near-infrared spectra of 65 cool stars with the NASA InfraRed Telescope Facility (IRTF) and analyze them to calculate accurate metallicities and stellar parameters. The sample of 55 M […]
Posted inAstrogeology, Astronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
Scaling K2 VII: Evidence For A High Occurrence Rate Of Hot Sub-Neptunes At Intermediate Ages
The NASA K2 mission obtained high precision time-series photometry for four young clusters, including the near-twin 600-800 Myr-old Praesepe and Hyades clusters.
Posted inAstrogeology, Exoplanets, -moons, -comets, Press Release
Scorching, Seven-Planet System Revealed by New Kepler Exoplanet List
A system of seven sweltering planets has been revealed by continued study of data from NASA’s retired Kepler space telescope: Each one is bathed in more radiant heat from their […]
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Press Release
The K2 & TESS Synergy II: Revisiting 26 systems in the TESS Primary Mission
The legacy of NASA’s K2 mission has provided hundreds of transiting exoplanets that can be revisited by new and future facilities for further characterization, with a particular focus on studying […]