Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 11 of 11 for “"abundance ratios"”.
-
Investigating the Relationship Between Chemical Abundance Ratios and Ages in Red Giant Stars
… of stellar pulsations by Kepler with chemical abundances from high quality spectra collected with HIRES, at the Keck Telescope, and kinematic information made available by the Gaia mission. Here, we dissect in depth a sample of 23 stars, making a detailed chemical analysis from their observed …
-
Investigating the Relationship Between Chemical Abundance Ratios and Ages in Red Giant Stars
… of stellar pulsations by Kepler with chemical abundances from high quality spectra collected with HIRES, at the Keck Telescope, and kinematic information made available by the Gaia mission. Here, we dissect in depth a sample of 23 stars, making a detailed chemical analysis from their observed …
-
Evolution of Galaxies - Star Formation Histories in Nearby Spheroids
… galaxy, some results were obtained; nonsolar abundance ratios in Elliptical galaxies (Es) achieved better fits between model and data than solar abundance ratios. For both early-type and late-type galaxies, best fits with non-solar abundance ratios were more constrained than in the solar …
-
Temperature-insensitive line ratios
We develop method to extract elemental abundance ratios using temperature-insensitive ratios of x-ray line fluxes for a collisionally ionized plasma. This method is then refined using more realistic plasma models for coronae of active stars. We finally apply the method to multiple sources and …
-
Ion Current Rectification in Nano/Micro-Fluidic Interfaces and Pulsed Glow Discharge Time-of-Flight Mass Spectrometric Chemical Speciation
… of GDToFMS, specific cluster ions or ion abundance ratios can be used for speciation of chromium oxides, manganese oxides, and iron oxides.;Chapters 3 and 4 focus on extending the application of pulsed glow discharge time-of-flight mass spectrometry for chemical speciation. Chapter 3 is …
-
Metallicities and stellar populations in spiral bulges
… lie close to, or within, the loci defining solar abundance ratio SSPs. The large number (24) of indices measured in this study, in conjunction with models of the effects of varying abundance ratios, permit the breaking of age/metallicity degeneracy and allow estimation of enhancements in specific …
-
Measurement of the Fluorine, Sodium, and Aluminum Fluxes in Cosmic Rays with the AMS Experiment on the International Space Station
… at the highest rigidities. The Na/Si and Al/Si abundance ratios at the source, 0.036 ± 0.003 for Na/Si and 0.103 ± 0.004 for Al/Si, are determined independent of cosmic ray propagation.
-
Sizing the X-ray spectral resolution limits of the REgolith X-ray Imaging Spectrometer (REXIS) instrument at Asteroid 1999RQ36
… as well as produce a global map of elemental abundance ratios. The accuracy requirement for measuring the global ratios of elements and the spectral resolution requirement for discriminating unique XRF lines from each other have been set in place. The correct interpretation of X-ray …
-
Kinematics and Stellar Populations in Brightest Cluster Galaxies
… (SSP)-equivalent ages, metallicities and α-abundance ratios. A systematic comparison was made between the indices and derived parameters for this sample of BOGs and those of large samples of ordinary elliptical galaxies in the same mass range. The derived properties were tested for possible …
-
Towards Generalized Characterization of Exoplanet Atmospheres with Transit Spectroscopy
… on cloud/haze properties and chemical abundances. Second, we apply our atmospheric retrieval framework to a large sample of 19 exoplanets ranging from cool mini-Neptunes to hot Jupiters. This effort constitutes the largest (i.e., broad wavelength coverage, multiple chemical species, …
-
Chemical and kinematical evolution in nearby dwarf spheroidal galaxies
… dSphs' characteristics, such as the a-element abundance patterns, stand in contradiction to the properties of stars in the Galactic halo. Further, yet unsolved, puzzles include the missing satellite problem, the influence of feedback and reionization, and the nature of dark matter. How then do …