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Full-Text Articles in Physical Sciences and Mathematics
Exploring The Hot And Gaseous Universe From Infrared To X-Ray, Chamani Gunasekera
Exploring The Hot And Gaseous Universe From Infrared To X-Ray, Chamani Gunasekera
Theses and Dissertations--Physics and Astronomy
Over 90% of baryonic matter in the universe exists as astrophysical plasmas. The gas
is often far from thermodynamic equilibrium, so numerical non-equilibrium spectral
synthesis simulations are used to understand observations. cloudy simulates vari-
ous physical conditions, providing spectra predictions. This thesis aims to meet the
challenge of new observatories like the JWST (James Webb Space Telescope) and
XRISM (X-Ray Imaging Spectroscopy Mission). These simulations are no better
than the underlying atomic and molecular database and the fourth chapter details
a long-needed update to an evolving database. The predicted spectra are strongly
affected by the composition of the gas, which …
A New Set Of Spectroscopic Metallicity Calibrations For Rr Lyrae Variable Stars, Eckhart Spalding
A New Set Of Spectroscopic Metallicity Calibrations For Rr Lyrae Variable Stars, Eckhart Spalding
Theses and Dissertations--Physics and Astronomy
RR Lyrae stars are old, iron-poor, Helium-burning variable stars. RR Lyraes are extremely useful for tracing phase-space structures and metallicities within the galaxy because they are easy to identify, have consistent luminosities, and are found in large numbers in the galactic disk, bulge, and halo. Here we present a new set of spectroscopic metallicity calibrations that use the equivalent widths of the Ca II K, Hγ, and Hδ lines to calculate metallicity values. Applied to spectroscopic survey data, these calibrations will help shed light on the evolution of the Milky Way and other galaxies.