The cosmic ray (CR) flux, as well as the hydrogen flux into the atmosphere of an exoplanet, can change the composition of the atmosphere. Here, we present the CR and […]
astro-ph.SR
![Illustration similar to that of Fig. 2 in Nimmo et al. (2020), demonstrating the sensitivity of core convection to changing concentrations of radiogenic elements (relative to the terrestrial amount), see Nimmo et al. (2020) for details on model parameters. Color scaled to represent net entropy production from radiogenic heating, with the black region representing negative production (no dynamo). Dashed red line represents the regime at [Eu/α]=0.08 where a dynamo failure lasting > 100 Myr first begins. Solid black lines represent contours of constant mantle temperature. astro-ph.SR](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/12/Distribution-of-Europium-in-The-Milky-Way-Disk.png?resize=1200%2C720&ssl=1)
Posted inAstrogeology, Atmospheres, Climate, Weather, Biogeochemical Cycles & Geobiology, Biophysics, Exoplanets, -moons, -comets, Gaia - Planetary Perspectives, Habitable Zones, Origin & Evolution of Life, Radiation, Status Report
Distribution of Europium in The Milky Way Disk; Its Connection to Planetary Habitability and The Source of The R-Process
The energy provided in the radioactive decay of thorium (Th) and uranium (U) isotopes, embedded in planetary mantles, sustains geodynamics important for surface habitability such as the generation of a […]
![The GCE-corrected, differential elemental abundance relative to the Sun ([X/Fe]solar - [X/Fe]star). The five solar twins with -0.1 < [Fe/H] < 0.1 dex, ∆ Teff < 100 K, ∆ log g < 0.1 are TOI-1055, TOI-2426, TOI-744, TOI-755, and TOI-818, are shown as gray symbols in the background, while the colored symbols show the average elemental abundance for these stars. Refractory elements are shown in orange, volatile elements are shown in blue symbols. Elements with Tc above 1300 K are considered refractory, with the threshold Tc of 1300 K shown by a dashed orange line. We fit a linear regression to the colored symbols while considering the error bars. The orange line displays the best linear fit to all the colored points, with the shaded blue band indicating the 1-σ confidence interval. The expression for the linear regression is -6.726e-05+2.320e−05 −2.342e−05 × Tc (K) + 0.086+0.030 −0.030. -- astro-ph.SR](https://i0.wp.com/astrobiology.com/wp-content/uploads/2024/11/High-Precision-Stellar-Chemical-Abundance.png?resize=1200%2C719&ssl=1)
Posted inAstrochemistry, Astronomy & Telescopes, Imaging & Spectroscopy, Space Weather & Heliophysics, Status Report, Stellar Cartography
High Precision Stellar Chemical Abundance for 17 Planet-hosting Stars and the Condensation Temperature Trend
The Sun is depleted in refractory elements compared to nearby solar twins, which may be linked to the formation of giant or terrestrial planets.
Posted inAtmospheres, Climate, Weather, Exoplanets, -moons, -comets, Habitable Zones, Proxima Centauri, Radiation, Space Weather & Heliophysics, Status Report, TRAPPIST-1
Magnetic Interaction of Stellar Coronal Mass Ejections with Close-in Exoplanets: Implication on Planetary Mass Loss and Ly-α Transits
Coronal Mass Ejections (CMEs) erupting from the host star are expected to have effects on the atmospheric erosion processes of the orbiting planets. For planets with a magnetosphere, the embedded […]
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Exoplanets, -moons, -comets, Space Weather & Heliophysics, Status Report, Stellar Cartography
Physics of mid- and Low-mass Stars with Solar-type Activity and Their Impact on Exoplanetary Environments
In the monograph, the authors systematize and generalize the results of studying solar-type activity that is characteristic of a significant part of mid- and low-mass stars of the Galaxy, outline […]
Posted inAstronomy & Telescopes, Atmospheres, Climate, Weather, Brown Dwarfs, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
Redshifting the Study of Cold Brown Dwarfs and Exoplanets: the Mid-Infrared Wavelength Region as an Indicator of Surface Gravity and Mass
JWST is opening many avenues for exploration. For cold brown dwarfs and exoplanets, JWST has opened the door to the mid-infrared wavelength region, where such objects emit significant energy.
Posted inAstronomy & Telescopes, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report
Examining The Rotation Of The Planet-hosting M Dwarf GJ 3942
Based on radial velocities, EXORAP photometry, and activity indicators, the HADES team reported a 16.3-day rotation period for the M dwarf GJ 3992. However, an RV–Hα magnitude-squared coherence estimate has […]
Posted inAstronomy & Telescopes, Imaging & Spectroscopy, Proxima Centauri, Radiation, Status Report, Stellar Cartography
X-Ray, UV, and Optical Observations of Proxima Centauri’s Stellar Cycle
Proxima Cen (GJ 551; dM5.5e) is one of only about a dozen fully convective stars known to have a stellar cycle, and the only one to have long-term X-ray monitoring.
Posted inAstronomy & Telescopes, Brown Dwarfs, Exoplanets, -moons, -comets, Gas Giants, Imaging & Spectroscopy, Status Report, Stellar Cartography
A Generative Model for Gaia Astrometric Orbit Catalogs: Selection Functions for Binary Stars, Giant Planets, and Compact Object Companions
Astrometry from Gaia DR3 has produced a sample of ∼170,000 Keplerian orbital solutions, with many more anticipated in the next few years. These data have enormous potential to constrain the […]
Posted inAstronomy & Telescopes, Biosignatures & Paleobiology, Habitable Zones, Imaging & Spectroscopy, Status Report, Stellar Cartography
Ultraviolet Photometry and Habitable Zones of Over 2700 Planet-Hosting Stars
The ongoing discovery of exoplanets has sparked significant interest in finding suitable worlds that could potentially support life. Stellar ultraviolet (UV; 100-3000 Å) radiation may play a crucial role in […]