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Full-Text Articles in Stars, Interstellar Medium and the Galaxy
Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey
Characterizing Cool Brown Dwarfs And Low-Mass Companions With Low-Resolution Near-Infrared Spectra, Paige Godfrey
Dissertations, Theses, and Capstone Projects
Exoplanet direct detections are reaching the temperature regime of cool brown dwarfs, motivating further understanding of the coolest substellar atmospheres. These objects, T and Y dwarfs, are numerous and isolated in the field, thus making them easier to study in detail than objects in companion systems. Brown dwarf spectral types are derived from spectral morphology and generally appear to correspond with decreasing mass and effective temperature (Teff). However, spectral subclasses of the colder objects do not share this monotonic temperature correlation, indicating that secondary parameters (gravity, metallicity, dust) significantly influence spectral morphology. These secondary atmospheric parameters can provide …
Diffuse Gamma-Ray Emission From Nearby Molecular Clouds As A Probe Of Cosmic Ray Density Variations, Ryan Abrahams
Diffuse Gamma-Ray Emission From Nearby Molecular Clouds As A Probe Of Cosmic Ray Density Variations, Ryan Abrahams
Dissertations, Theses, and Capstone Projects
We analyze gamma-ray emission from nearby, interstellar molecular clouds in order to calibrate current tracers of the interstellar medium and to probe local cosmic ray gradients. Gamma-rays detected by the Fermi Gamma-ray Space Telescope are created when cosmic rays collide with atomic nuclei in the interstellar medium, and thus provide a unique, unbiased view of the distribution of gas. The gamma-ray flux per proton in the interstellar medium, also known as the gamma-ray emissivity, contains information about the density of high energy cosmic rays. These cosmic rays are born in supernovae shock waves and diffuse throughout the Galaxy. The cosmic …