Results 61 to 70 of about 2,716 (200)

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

Meteoritics &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, A. Vyjidak, G. A. Baratta, B. M. Giuliano, R. G. Urso, C. Scirè, D. Fulvio, T. Grassi, P. Jusko, P. Caselli, M. E. Palumbo   +10 more
wiley   +1 more source

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

Meteoritics &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, Alexander M. Kling, Luke Daly, Dieter Isheim, David N. Seidman, Michelle S. Thompson, Philipp R. Heck   +6 more
wiley   +1 more source

Spatial Variations of Stellar Elemental Abundances in FIRE Simulations of Milky Way-mass Galaxies: Patterns Today Mostly Reflect Those at Formation

The Astrophysical Journal
Spatial patterns of stellar elemental abundances encode rich information about a galaxy’s formation history. We analyze the radial, vertical, and azimuthal variations of metals in stars, both today and at formation, in the FIRE-2 cosmological simulations
Russell L. Graf, Andrew Wetzel, Matthew A. Bellardini, Jeremy Bailin   +3 more
doaj   +1 more source

The chemical evolution of galaxies

Metals -- heavy elements synthesized during various phases of stellar evolution or during supernova explosions -- play a fundamental role in shaping galaxy evolution. In fact, their relative abundances, spatial distribution, and scaling with galactic properties reflect the constant interplay between star-formation, nucleosynthesis, and gas flows that ...
openaire   +2 more sources

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

Meteoritics &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, Suzette Timmerman, Ingo Leya   +2 more
wiley   +1 more source

Turbulent Gas-rich Disks at High Redshift: Origin of Thick Stellar Disks Through 3D “Baryon Sloshing”

The Astrophysical Journal
In response to recent observations from JWST and Atacama Large Millimeter Array, we explore a new class of dynamically self-consistent models that mimics a plausible progenitor of the Milky Way over a wide range of disk gas fractions, f _gas .
Joss Bland-Hawthorn, Thor Tepper-Garcia, Oscar Agertz, Christoph Federrath, Misha Haywood, Paola di Matteo, Timothy R. Bedding, Takafumi Tsukui, Emily Wisnioski, Melissa Ness, Ken Freeman   +10 more
doaj   +1 more source

Low‐dose X‐ray radiation induces an adaptive response: A potential countermeasure to galactic cosmic radiation exposure

Experimental Physiology, EarlyView.
Abstract Space exploration involves many dangers including galactic cosmic radiation (GCR). This class of radiation includes high‐energy protons and heavy ionizing ions. NASA has defined GCR as a carcinogenic risk for long‐duration space missions. To date, no clear strategy has been developed to counter chronic GCR exposure.
Siena Edwards, Jessica Adams, Anastasia Tchernikov, John G. Edwards   +3 more
wiley   +1 more source

Under Pressure: Decoding the Effect of High Densities on Derived Nebular Properties

The Astrophysical Journal
Recent JWST observations have uncovered a population of compact, high-redshift ( z  > 6) galaxies exhibiting extreme nebular conditions and enhanced nitrogen abundances that challenge standard chemical evolution paradigms.
Zorayda Martinez, Danielle A. Berg, Bethan L. James, Karla Z. Arellano-Córdova, Daniel P. Stark, Peter Senchyna, Evan D. Skillman, Noah S. J. Rogers, John Chisholm   +8 more
doaj   +1 more source

Chemical Evolution of Galaxies

, 2001
Chemical abundances provide important clues to the evolution of galaxies. Ionized nebulae are one of the main sources of chemical abundance measurements, especially in external galaxies. Studies of H II regions have shown that the overall metallicity of galaxies increases with galactic luminosity, and that spiral galaxies characteristically have radial
openaire   +2 more sources

Spaceborne and spaceborn: Physiological aspects of pregnancy and birth during interplanetary flight

Experimental Physiology, EarlyView.
Abstract Crewed interplanetary return missions that are on the planning horizon will take years, more than enough time for initiation and completion of a pregnancy. Pregnancy is viewed as a sequence of processes – fertilization, blastocyst formation, implantation, gastrulation, placentation, organogenesis, gross morphogenesis, birth and neonatal ...
Arun V. Holden
wiley   +1 more source