Results 111 to 120 of about 8,038 (253)

Raios cósmicos e a heliosfera

open access: yesRevista Brasileira de Ensino de Física
Este texto sintetiza a modulação pelas partículas do fluxo de raios cósmicos galáticos durante seu transporte na heliosfera, fornecendo algumas referências necessárias para a compreensão do assunto aos interessados no tema.
A.G. Izzo de Oliveira   +2 more
doaj   +1 more source

Raman analysis of organic refractory materials after energetic processing: Evidence for amorphous carbon on TNOs and comets

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract Amorphous carbon (αC) is found in various extraterrestrial particles, including those thought to originate from the outer Solar System. αC can form through two main processes involving C‐rich materials: exposure to energetic charged particles and thermal processing.
M. Germanà   +10 more
wiley   +1 more source

Nanoscale space weathering features in mature lunar soil revealed by TEM and APT

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract Space weathering significantly alters the optical, chemical, and structural properties of lunar regolith at micro‐ and nanoscales; yet detailed nanoscale variability within individual soils remains underexplored. Here we apply transmission electron microscopy (TEM) and atom probe tomography to four mineral grains (olivine, ilmenite, and two ...
Jennika Greer   +6 more
wiley   +1 more source

Updated model of cosmic-ray-induced ionization in the atmosphere (CRAC:CRII_v3): Improved yield function and lookup tables

open access: yesJournal of Space Weather and Space Climate
Cosmic rays, including galactic cosmic rays and solar energetic particles, form the main source of ionization of the low and middle atmosphere, which is important for various chemical and physical effects in the atmosphere.
Usoskin I.G.   +2 more
doaj   +1 more source

Potassium isotopic compositions and exposure ages of evolved and silica‐rich achondrites

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract Some of the oldest igneous rocks in the Solar System include evolved and silica‐rich achondrites that originate from parent bodies less than 1000 km in diameter, referred to as planetesimals. While Earth was initially in a molten state and required continental crust formation and plate tectonics to generate andesite bulk compositions, evolved ...
Z. Vaci   +9 more
wiley   +1 more source

The 40K‐K dating system: 1. Improving data interpretation using new model calculations

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract The 40K‐K cosmic‐ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic 40K with the stable cosmogenic isotopes 39K and 41K. However, earlier applications relied on semi‐empirical production models and inconsistent analytical data sets, limiting their ...
Farshid Nozarian   +2 more
wiley   +1 more source

The Correspondence between Leaky-box and Diffusion Models of Cosmic-Ray Propagation

open access: yesThe Astrophysical Journal
The leaky-box model and the attendant concept of path-length distribution of cosmic rays were invented in the mid-1960s. Even though versatile computational packages such as GALPROP and DRAGON with the diffusion approach are now available for analyzing ...
Ramanath Cowsik, Dawson Huth
doaj   +1 more source

Characterization of coesite‐bearing impact melt glass from the Hapcheon crater, Korea: Trimodal phase architecture, shock metamorphism, and implications for 40Ar/39Ar geochronology

open access: yesMeteoritics &Planetary Science, EarlyView.
Abstract We present the first micrometer‐scale, phase‐resolved compositional characterization of impact melt glass from the Hapcheon crater (~1.4 km apparent diameter), the first confirmed impact structure on the Korean Peninsula, integrating EPMA‐WDS (5 μm spot), confocal Raman spectroscopy (<1 μm spot), XRD, and 40Ar/39Ar step‐heating geochronology ...
Jin‐Young Lee   +2 more
wiley   +1 more source

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