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2016

Dust

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Articles 1 - 11 of 11

Full-Text Articles in Physical Sciences and Mathematics

Structure And Physical Conditions In The Huygens Region Of The Orion Nebula, C. R. O'Dell, Gary J. Ferland, M. Peimbert Oct 2016

Structure And Physical Conditions In The Huygens Region Of The Orion Nebula, C. R. O'Dell, Gary J. Ferland, M. Peimbert

Physics and Astronomy Faculty Publications

Hubble Space Telescope images, MUSE maps of emission lines, and an atlas of high velocity resolution emission-line spectra have been used to establish for the first time correlations of the electron temperature, electron density, radial velocity, turbulence, and orientation within the main ionization front of the nebula. From the study of the combined properties of multiple features, it is established that variations in the radial velocity are primarily caused by the photoevaporating ionization front being viewed at different angles. There is a progressive increase of the electron temperature and density with decreasing distance from the dominant ionizing star θ1 …

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Variations In Geochemistry And Mineralogy Of Aeolian Dust Deposition To Mountains In Utah And Nevada, Usa, Dylan Binder Dastrup Oct 2016

Variations In Geochemistry And Mineralogy Of Aeolian Dust Deposition To Mountains In Utah And Nevada, Usa, Dylan Binder Dastrup

Theses and Dissertations

Major and trace metal loading to mountains in the western US depends on dust sources, intensity of storms and their availability for transport during snowmelt and runoff. Previous work has been conducted on dust production, composition, and its affect on solar radiation and timing of snow melt. This study was conducted to 1) examine temporal and spatial variability in dust chemistry; 2) evaluate form and availability of major and trace elements in dust; and 3) identify potential dust sources affecting mountains in Utah and Nevada. Spring and summertime dust was collected across northern Utah over the course of three years …

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Aerosols Size Distribution Characteristics And Role Of Precipitation During Dust Storm Formation Over Saudi Arabia, Ashraf Farahat, Hesham El-Askary, A. Umran Dogan Oct 2016

Aerosols Size Distribution Characteristics And Role Of Precipitation During Dust Storm Formation Over Saudi Arabia, Ashraf Farahat, Hesham El-Askary, A. Umran Dogan

Mathematics, Physics, and Computer Science Faculty Articles and Research

Kingdom of Saudi Arabia and the Gulf region are frequently exposed to major dust storms and anthropogenic emissions from rapidly growing industrial activities that affect aerosols optical and physical characteristics. This paper integrates observations from space-borne sensors namely MODIS and CALIPSO, together with AERONET ground observations to examine eight years aerosols characteristics during the (March–May) season of 2003 to 2010 over Saudi Arabia. Aerosol analysis from the interdependent data assessment show comparable aerosols characteristics over the eight year period with higher aerosols mean optical depths over enhanced dust load region, (46–50°E, 25–29°N), during March–May of 2009 and 2010. The mean …

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The Spectral Variability Of Astronomical Pahs, Matthew Shannon Aug 2016

The Spectral Variability Of Astronomical Pahs, Matthew Shannon

Electronic Thesis and Dissertation Repository

Polycyclic aromatic hydrocarbons (PAHs) are highly abundant molecules found throughout the universe. Illuminated by ultraviolet photons, they can emit up to 10% of the total power output of star-forming galaxies and are involved in many important physical and chemical processes (e.g., gas heating). They produce prominent emission bands between 3-20 μm which vary strongly in intensity and spectral profile. The origins of these variations are not fully understood, which limits the use of PAHs as (ubiquitous) diagnostic tracers of physical conditions. To characterize their variability, we studied the relative intensities and profiles of the 10-20 μm PAH bands in a …

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The C-H Stretching Features At 3.2-3.5 Μm Of Polycyclic Aromatic Hydrocarbons With Aliphatic Sidegroups, Xuejuan Yang, Aigen Li, Rainer Glaser, Jianxin Zhong Jun 2016

The C-H Stretching Features At 3.2-3.5 Μm Of Polycyclic Aromatic Hydrocarbons With Aliphatic Sidegroups, Xuejuan Yang, Aigen Li, Rainer Glaser, Jianxin Zhong

Chemistry Faculty Research & Creative Works

The so-called "unidentified" infrared emission (UIE) features at 3.3, 6.2, 7.7, 8.6, and 11.3 μm are ubiquitously seen in a wide variety of astrophysical regions. The UIE features are characteristic of the stretching and bending vibrations of aromatic hydrocarbon materials, e.g., polycyclic aromatic hydrocarbon (PAH) molecules. The 3.3 μm aromatic C-H stretching feature is often accompanied by a weaker feature at 3.4 μm. The latter is generally thought to result from the C-H stretch of aliphatic groups attached to the aromatic systems. The ratio of the observed intensity of the 3.3 μm aromatic C-H feature to that of the 3.4 …

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Dynamical Characteristics Of Atmospheric Aerosols Over Ig Region, Manish Sharma, Ramesh P. Singh, Rajesh Kumar May 2016

Dynamical Characteristics Of Atmospheric Aerosols Over Ig Region, Manish Sharma, Ramesh P. Singh, Rajesh Kumar

Mathematics, Physics, and Computer Science Faculty Articles and Research

The dynamical characteristics of atmospheric aerosols over the Indo-Gangetic (IG) region are primarily dependent on the geographical settings and meteorological conditions. Detailed analysis of multi satellite data and ground observations have been carried out over three different cities i.e. Kanpur, Greater Noida and Amritsar during 2010-2013. Level-3 Moderate Resolution Imaging Spectroradiometer (MODIS) terra daily global grid product with spatial resolution of 1° × 1° shows the mean AOD at 500 nm wavelength value of 0.73, 0.70 and 0.67 with the standard deviation of 0.43, 0.39 and 0.36 respectively over Amritsar, Greater Noida and Kanpur. Our detailed analysis shows characteristic behavior …

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Late Holocene Climate And Environmental Reconstruction Derived From The Asian Ice Core Array (Aica), Bjorn Grigholm May 2016

Late Holocene Climate And Environmental Reconstruction Derived From The Asian Ice Core Array (Aica), Bjorn Grigholm

Electronic Theses and Dissertations

Recent climate change has impacted natural and human systems across the Earth, emphasizing the need for greater understanding of both the existing and changing natural and anthropogenic forcing mechanisms and subsequent responses of the Earth’s climate system. High-resolution, multi-parameter ice core records retrieved and analyzed from two Asian Ice Core Array (AICA) sites, Geladaindong (central Tibetan Plateau) and Inilchek (central Tien Shan) were utilized to reconstruct atmospheric chemical concentrations and composition over the past ~100-500 years, improving the understanding of late Holocene climate and environmental variability in Asia. Both ice cores were analyzed for major and trace elements, major soluble …

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Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano Mar 2016

Peering Through The Dust: Nustar Observations Of Two First-2mass Red Quasars, Stephanie M. Lamassa, Angelo Ricarte, Eilat Glikman, C. Megan Urry, Daniel Stern, Tahir Yaqoob, George B. Lansbury, Francesca Civano

Dartmouth Scholarship

Some reddened quasars appear to be transitional objects in the merger-induced black hole growth/galaxy evolution paradigm, where a heavily obscured nucleus starts to be unveiled by powerful quasar winds evacuating the surrounding cocoon of dust and gas. Hard X-ray observations are able to peer through this gas and dust, revealing the properties of circumnuclear obscuration. Here, we present NuSTAR and XMM-Newton/Chandra observations of FIRST-2MASS selected red quasars F2M 0830+3759 and F2M 1227+3214. We find that though F2M 0830+3759 is moderately obscured (NH,Z=2.1±0.2×1022 cm−2) and F2M 1227+3214 is mildly absorbed (NH,Z=3.4+0.8−0.7×1021 cm−2 …

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Uranium-Series And Strontium Isotope Ratios In Soils From Basse-Terre Island, French Guadeloupe: Insights For Rapid Soil Formation And Impact Of Dust In A Tropical Volcanic Setting, Yvette Pereyra Jan 2016

Uranium-Series And Strontium Isotope Ratios In Soils From Basse-Terre Island, French Guadeloupe: Insights For Rapid Soil Formation And Impact Of Dust In A Tropical Volcanic Setting, Yvette Pereyra

Open Access Theses & Dissertations

Chemical weathering of silicate rocks generates soils that contain mineral nutrients, sustain ecosystems, modify water chemistry in the hydrosphere, and regulate the global carbon cycle. Understanding the timescales of soil formation and sources of soil mineral nutrients has great implications for securing the future of agriculture and food production. However, few tools are currently available to directly quantify the rates of chemical weathering and timescales of soil formation. Uranium-series isotopes fractionate during chemical weathering and the activity ratios of (234U/238U), (230Th/238U), (238U/232Th) and (230Th/232Th) have great potential to constrain the rates and timescales of chemical weathering and soil formation in …

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Fine Particulate Air Pollution In Saudi Arabia : Implications For Cardiopulmonary Morbidity, Shedrack Rujooga Nayebare Jan 2016

Fine Particulate Air Pollution In Saudi Arabia : Implications For Cardiopulmonary Morbidity, Shedrack Rujooga Nayebare

Legacy Theses & Dissertations (2009 - 2024)

Fine particulate (PM2.5) air pollution is a major issue in Saudi Arabia. Though the health effects of exposure to PM2.5 have been extensively studied in developed countries of Europe and North America, this research is yet to be done in developing countries of Africa, some parts of Asia and the Middle East including Saudi Arabia. This is the first comprehensive assessment of PM2.5 air pollution in Saudi Arabia describing the major emission sources as well as assessing the association of daily exposures to PM2.5 and its chemical constituents with cardiopulmonary morbidity.

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Circumstellar Dust Shells: Clues To The Evolution Of R Coronae Borealis Stars, Edward Joseph Montiel Jan 2016

Circumstellar Dust Shells: Clues To The Evolution Of R Coronae Borealis Stars, Edward Joseph Montiel

LSU Doctoral Dissertations

The existence of extended, cold dust envelopes surrounding R Coronae Borealis (RCB) stars has been known about for over 30 years. RCB stars are an exotic group of extremely hydrogen-deficient, carbon-rich supergiants that are known for their spectacular declines in brightness (up to 8 mags) at irregular intervals. There are three possible origins of these envelopes: (1) they are fossil planetary nebulae (PNe), indicating that RCB stars formed via a final Helium-shell flash; (2) they are the remnant material from the merger of a CO and a He white dwarf binary, (3) they have been constructed from dust ejection events …

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