Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Earth Sciences (8613)
- Life Sciences (8361)
- Soil Science (7964)
- Plant Sciences (7719)
- Agronomy and Crop Sciences (3129)
-
- Agricultural Science (3116)
- Plant Biology (3106)
- Plant Pathology (3105)
- Weed Science (3100)
- Environmental Sciences (1177)
- Engineering (1094)
- Physics (847)
- Astrophysics and Astronomy (579)
- Environmental Monitoring (559)
- Materials Science and Engineering (537)
- Mechanical Engineering (528)
- Geology (526)
- Sustainability (515)
- Oil, Gas, and Energy (510)
- Environmental Indicators and Impact Assessment (505)
- Chemistry (491)
- Mining Engineering (485)
- Energy Systems (473)
- Structural Materials (473)
- Statistics and Probability (367)
- Medicine and Health Sciences (339)
- Computer Sciences (320)
- Water Resource Management (270)
- Agriculture (194)
- Keyword
-
- Grazing (336)
- Kentucky (307)
- Gas (255)
- And Energy; Structural Materials; Sustainability (248)
- Energy Systems; Environmental Indicators and Impact Assessment; Environmental Monitoring; Mining Engineering; Oil (248)
-
- Alfalfa (169)
- Nitrogen (168)
- Grassland (155)
- Forage (149)
- Pasture (147)
- Cattle (142)
- Sheep (140)
- Climate change (128)
- Biodiversity (124)
- Yield (121)
- Forage quality (114)
- Silage (113)
- Livestock (100)
- Nutritive value (96)
- Phosphorus (96)
- Digestibility (95)
- Grasslands (92)
- Sustainability (92)
- Legumes (89)
- Grazing management (87)
- Management (86)
- Soil (85)
- Intake (84)
- Perennial ryegrass (84)
- Grass (81)
- Publication Year
- Publication
-
- IGC Proceedings (1993-2023) (7001)
- Physics and Astronomy Faculty Publications (681)
- World of Coal Ash Proceedings (472)
- Kentucky Alfalfa and Stored Forage Conference (382)
- KWRRI Research Reports (252)
-
- Map and Chart--KGS (232)
- Soil Science News and Views (183)
- Chemistry Faculty Publications (182)
- Kentucky Grazing Conference (176)
- Kentucky Water Resources Annual Symposium (154)
- Theses and Dissertations--Chemistry (141)
- Theses and Dissertations--Physics and Astronomy (121)
- Theses and Dissertations--Mathematics (117)
- Agriculture and Natural Resources Publications (116)
- University of Kentucky Doctoral Dissertations (112)
- Theses and Dissertations--Earth and Environmental Sciences (106)
- Biosystems and Agricultural Engineering Faculty Publications (103)
- Theses and Dissertations--Computer Science (95)
- Plant and Soil Sciences Faculty Publications (83)
- Report of Investigations--KGS (69)
- Theses and Dissertations--Statistics (66)
- Information Circular--KGS (61)
- Biostatistics Faculty Publications (58)
- Chemistry Faculty Patents (44)
- Mathematics Faculty Publications (44)
- Commonwealth Computational Summit (41)
- Forestry and Natural Resources Faculty Publications (40)
- Computer Science Faculty Publications (38)
- University of Kentucky Master's Theses (36)
- Statistics Faculty Publications (33)
- Publication Type
- File Type
Articles 11311 - 11340 of 12002
Full-Text Articles in Physical Sciences and Mathematics
A Deep-To-Shallow Transition In The Fort Payne Formation (Lower Mississippian), Kentucky Highway 61, Cumberland County, Kentucky, David L. Meyer, Paul E. Potter, Jennifer L. Thies, William I. Ausich, Stephen A. Leslie
A Deep-To-Shallow Transition In The Fort Payne Formation (Lower Mississippian), Kentucky Highway 61, Cumberland County, Kentucky, David L. Meyer, Paul E. Potter, Jennifer L. Thies, William I. Ausich, Stephen A. Leslie
Map and Chart--KGS
The Fort Payne Formation of the Cumberland Saddle region of south-central Kentucky and north-central Tennessee is part of a vast marine sedimentation system that extended over much of North America during the Early Mississippian Period; broadly similar facies reached from Georgia through Tennessee and Kentucky, into western Illinois and Missouri, and into New Mexico and the northern Rockies (Pryor and Sable, 1974). Throughout North America the Fort Payne and its equivalents overlie a black shale (in Kentucky called the Chattanooga Shale) and underlie thick carbonates (in Kentucky, the Warsaw Formation and younger middle Mississippian limestones).
Six miles south of Burkesville, …
Profitability Of Variable Rate Fertilization On A Kentucky Soil (A Theoretical Analysis), Lloyd W. Murdock, Paula L. Howe
Profitability Of Variable Rate Fertilization On A Kentucky Soil (A Theoretical Analysis), Lloyd W. Murdock, Paula L. Howe
Soil Science News and Views
Grid soil sampling and variable rate fertilizer applications are a part of the precision agriculture movement that has captured the interest of many farmers. Variable rate fertilization requires extra expense and effort plus the use of often unfamiliar technology. Global Positioning Systems (GPS) equipment and computer software are used to outline and grid the field into small manageable units or “cells” (usually 2.5 acres). Each grid cell is soil sampled and tested for pH and available nutrients. Fertilizer recommendations are made on each grid cell and the fertilizer is spread by each grid cell using a truck equipped with GPS …
Hydrogeology And Ground-Water Monitoring Of Coal-Ash Disposal Sites In A Karst Terrane Near Burnside, South-Central Kentucky, Shelley Minns Hutcheson, Lyle V. A. Sendlein, James S. Dinger, James C. Currens, Arsin M. Sahba
Hydrogeology And Ground-Water Monitoring Of Coal-Ash Disposal Sites In A Karst Terrane Near Burnside, South-Central Kentucky, Shelley Minns Hutcheson, Lyle V. A. Sendlein, James S. Dinger, James C. Currens, Arsin M. Sahba
Report of Investigations--KGS
The effects of two coal-ash disposal facilities on ground-water quality at the John Sherman Cooper Power Plant, located in a karst region of south-central Kentucky, were evaluated using dye traces in springs. Springs were used for monitoring rather than wells, because in a karst terrane wells are unlikely to intercept individual conduits.
A closed-out ash pond located over a conduit-flow system discharges to three springs in the upper Salem and Warsaw Formations along Lake Cumberland. Water discharging from these downgradient springs is similar to springs unaffected by ash-disposal facilities and is a calcium-bicarbonate type. No constituent concentrations found in this …
Fresh-Water Aquifer In The Knox Group (Cambrian–Ordovician) Of Central Kentucky, James A. Kipp
Fresh-Water Aquifer In The Knox Group (Cambrian–Ordovician) Of Central Kentucky, James A. Kipp
Report of Investigations--KGS
Fresh water can be found in Cambrian and Ordovician carbonate rocks of the Knox Group in central Kentucky. The top of the aquifer is as much as 300 ft above mean sea level (m.s.l.) on the crest of the Cincinnati Arch, but descends off the flanks of the arch. Water is normally found in the upper 100 to 250 ft of the Knox, primarily in secondary porosity apparently associated with the unconformity at the top of the unit. Knox wells commonly exceed 750 ft in total depth, but because the aquifer is artesian, water rises to an elevation of about …
Computer Modeling Of The North Fork Of The Kentucky River Using Swat And Basins, T. Bischoff, S. Yost, L. Ormsbee, T. Stumbur
Computer Modeling Of The North Fork Of The Kentucky River Using Swat And Basins, T. Bischoff, S. Yost, L. Ormsbee, T. Stumbur
KWRRI Research Reports
The purpose of this study was to investigate possible watershed models for use in the State of Kentucky's new watershed framework initiative and to apply the selected model(s) to the North Fork of the Kentucky River as part of an initial pilot project. SWAT and BASINS models were compared.
Gis Linkage With Hydrologic Models: Application To The North Fork Of The Kentucky River (With Geo-Spatial Data Needs And Sources), T. Stumbur, L. Ormsbee
Gis Linkage With Hydrologic Models: Application To The North Fork Of The Kentucky River (With Geo-Spatial Data Needs And Sources), T. Stumbur, L. Ormsbee
KWRRI Research Reports
This report focuses on links between GIS and hydrologic models and geo-spatial data needs and sources. The use and calibration of the hydrologic models reviewed in this paper are addressed by another report (see Bischoff, Yost, Ormsbee 1997.)
Part 1 of this report explains the general principles of a GIS database. It gives an overview of the Arc/Info and ArcView data models by providing a brief description of each spatial data format and explaining how spatial and tabular data are linked in a GIS environment. Part 1 also addresses the data compatibility issues related to projection, scale and resolution of …
Kentucky Watershed Priority Formula: Application Guidelines And Data Requirements, L. Ormsbee, Lee Colten
Kentucky Watershed Priority Formula: Application Guidelines And Data Requirements, L. Ormsbee, Lee Colten
KWRRI Research Reports
This report presents a methodology for ranking and selecting individual 11-digit HUCs for subsequent development of detailed watershed management plans as part of the Kentucky Watershed Management Framework. The proposed methodology consists of two phases: 1) Prioritization and 2) Targeting. The prioritization phase is used to rank 11-digit HUCs on the basis of existing special protection areas and the existence or potential existence of designated use impairment. The prioritization is accomplished using a priority watershed formula developed especially for this purpose. The formula is intended to serve as an objective tool for compiling environmental indicators to rank watershedsand for use …
How Accurate Are Uk's Nitrogen Recommendations For Corn?, Kenneth L. Wells, James E. Dollarhide, David C. Ditsch
How Accurate Are Uk's Nitrogen Recommendations For Corn?, Kenneth L. Wells, James E. Dollarhide, David C. Ditsch
Soil Science News and Views
Average corn yields produced on soils with high yield potential have steadily been increasing in Kentucky during the past several years. Yields from such soils in years with adequate amounts of rainfall well distributed over the growing season (May-September) may average 180 to 200 bushels per acre. A bushel of corn with crude protein content of 8 to 9% contains about 1.3 to 1.4% total nitrogen (N) on a dry matter basis. This is about 0.6 to 0.7 lbs total N per bushel of corn (at 15.5% moisture), or 108 to 126 lbs N per acre for a 180 bu/A …
Economics Of Precision Farming: Payoff In The Future, Jess Lowenberg-Beboer
Economics Of Precision Farming: Payoff In The Future, Jess Lowenberg-Beboer
Soil Science News and Views
Precision agriculture is an infant technology. This infant has some of the signs of eventual greatness, but its full capacities will not be evident for some years. Like all infants, it will require an investment of time and resources to help it to maturity. This investment will have some short term payoff, but the main benefits will be in the future.
The purpose of this presentation is to help you manage your adoption of precision farming technology for that future payoff. The specific objectives will be to:review what we have learned about the economics of precision farming, identify future benefits, …
Tillage Slows Fecal Bacteria Infiltration Through Soil, Mark S. Coyne, S. W. Mcmurry, E. Perfect
Tillage Slows Fecal Bacteria Infiltration Through Soil, Mark S. Coyne, S. W. Mcmurry, E. Perfect
Soil Science News and Views
Bacterial pathogens can degrade ground water quality by infiltrating and eroding from land treated with poultry wastes. The potential for ground water contamination (as well as associated health risks and cost of water treatment) greatly depends on the depth of soil to the water table or bedrock and soil structure. Pathogens must move through the soil profile to contaminate ground water (although sinkholes can provide a direct channel from the soil surface to the water table in karst areas). Deep soils have less potential for contamination than shallow soils. Structureless soils retain fecal bacteria better than well structured soils. Research …
Filter Strip Length And Fecal Bacteria Trapping From Poultry Waste - An Update, Mark S. Coyne, R. A. Gilfillen, Robert L. Blevins
Filter Strip Length And Fecal Bacteria Trapping From Poultry Waste - An Update, Mark S. Coyne, R. A. Gilfillen, Robert L. Blevins
Soil Science News and Views
Cheap, efficient, and environmentally sound waste disposal will be needed as Kentucky's broiler industry expands. The filter strip length needed to protect water resources from contaminants in surface runoff is a pressing issue in waste management and water quality. In a previous Soil Science News and Views (Vol. 15, No. 8) we reported that grass filter strips as short as 15 feet can trap over 90% of the fecal bacteria eroding from land-applied and incorporated poultry waste during runoff following rainstorms. In this update, we provide some additional information and conclusions from that study on filter strip length, based on …
Soil Management For Intensive Grazing, Kenneth L. Wells, Charles T. Dougherty
Soil Management For Intensive Grazing, Kenneth L. Wells, Charles T. Dougherty
Soil Science News and Views
Recycling of plant nutrients is of major concern in managing paddocks in pasturefields for intensive grazing. Redistribution of nutrients present in fecal and urine deposits is an important issue in growing climatically and seasonally-adapted forage species and for efficient conversion of herbage into animal products while adding to the sustainability of the system. Some of the questions that arise in managing soils for intensive grazing are discussed below.
Indicator Bacteria Concentrations Of Two Northwest Arkansas Streams In Relation To Flow And Season, Dwayne R. Edwards, Mark S. Coyne, Tommy C. Daniel, P. F. Vendrell, J. F. Murdoch, P. A. Moore Jr.
Indicator Bacteria Concentrations Of Two Northwest Arkansas Streams In Relation To Flow And Season, Dwayne R. Edwards, Mark S. Coyne, Tommy C. Daniel, P. F. Vendrell, J. F. Murdoch, P. A. Moore Jr.
Biosystems and Agricultural Engineering Faculty Publications
Concentrations of indicator bacteria such as fecal coliform (FC) and fecal streptococcus (FS) are often used to assess the suitability of waters for their intended use(s) and to allocate resources for water quality improvement measures. There is evidence, however, that concentrations of FC and FS can be influenced by variables such as season and flow rate during sampling, which could lead to biased results. The objective of this study was to assess the impacts of season and flow rate on concentrations of FC and FS. Fecal indicator bacteria concentrations were measured for approximately three years at five sites on two …
Oil And Gas Map Of The Middlesboro 30 X 60 Minute Quadrangle, Kentucky, Anna E. Watson, Lance G. Morris, Brandon C. Nuttall, Daniel I. Carey
Oil And Gas Map Of The Middlesboro 30 X 60 Minute Quadrangle, Kentucky, Anna E. Watson, Lance G. Morris, Brandon C. Nuttall, Daniel I. Carey
Map and Chart--KGS
The purpose of the oil and gas map series is to portray the distribution of oil and gas resources in a manner useful to the oil and gas industry and to others interested in subsurface research.
Runoff Quality Responses To Cattle-Gazing Strategy And Grassed Buffer Zone Length, Dwayne R. Edwards, Brian T. Larsen, Teng T. Lim
Runoff Quality Responses To Cattle-Gazing Strategy And Grassed Buffer Zone Length, Dwayne R. Edwards, Brian T. Larsen, Teng T. Lim
KWRRI Research Reports
Grazed pastures represent a source of potential nonpoint pollution. In comparison to other nonpoint sources (e.g., row-cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from simulated grazed pasture is influenced by grazing duration (4-12 weeks), grazing strategy (no grazing, conventional grazing and rotational grazing), and by the use of grassed buffer strips (ranging in length from O to 18.3 m) installed down-slope …
Development Of A River Basin Management Framework Using Gis And Watershed Modeling: Application To The North Fork Of The Kentucky River, L. Ormsbee, S. Yost, T. Stumbur, T. Bischoff
Development Of A River Basin Management Framework Using Gis And Watershed Modeling: Application To The North Fork Of The Kentucky River, L. Ormsbee, S. Yost, T. Stumbur, T. Bischoff
KWRRI Research Reports
No abstract provided.
Physical Conditions In Low-Ionization Regions Of The Orion Nebula, J. A. Baldwin, A. Crotts, R. J. Dufour, Gary J. Ferland, S. Heathcote, J. J. Hester, K. T. Korista, P. G. Martin, C. R. O'Dell, R. H. Rubin, A. G. G. M. Tielens, D. A. Verner, D. K. Walter, Z. Wen
Physical Conditions In Low-Ionization Regions Of The Orion Nebula, J. A. Baldwin, A. Crotts, R. J. Dufour, Gary J. Ferland, S. Heathcote, J. J. Hester, K. T. Korista, P. G. Martin, C. R. O'Dell, R. H. Rubin, A. G. G. M. Tielens, D. A. Verner, D. K. Walter, Z. Wen
Physics and Astronomy Faculty Publications
We reexamine the spectroscopic underpinnings of recent suggestions that [O I] and [Fe II] lines from the Orion H II region are produced in gas where the iron-carrying grains have been destroyed and the electron density is surprisingly high. Our new observations show that previous detections of [O I] 5577 were dominated by telluric emission. Our limits are consistent with a moderate density (≈ 104 cm-3) photoionized gas. We show that a previously proposed model of the Orion H II region reproduces the observed [O I] and [Fe II] spectrum. These lines are fully consistent with formation …
Rate Coefficients For Charge Transfer Between Hydrogen And The First 30 Elements, J. B. Kingdon, Gary J. Ferland
Rate Coefficients For Charge Transfer Between Hydrogen And The First 30 Elements, J. B. Kingdon, Gary J. Ferland
Physics and Astronomy Faculty Publications
We present analytic fits to charge exchange rate coefficients over the full range of temperatures which occurs in photoionized or shock-heated plasmas. We consider reactions between neutral hydrogen and all elements with parent ion charge q = 1-4 up to Z = 30. Many rates were obtained from various sources in the literature. For reactions for which no data were available, we calculated rates using the Landau-Zener formalism. For these new reactions, we tabulate both total and state-specific rate coefficients. Ml are fitted with a consistent, accurate formula. These fits may be incorporated easily into spectral synthesis codes, and we …
Atomic Data For Astrophysics. Ii. New Analytic Fits For Photoionization Cross Sections Of Atoms And Ions, D. A. Verner, Gary J. Ferland, K. T. Korista, D. G. Yakovlev
Atomic Data For Astrophysics. Ii. New Analytic Fits For Photoionization Cross Sections Of Atoms And Ions, D. A. Verner, Gary J. Ferland, K. T. Korista, D. G. Yakovlev
Physics and Astronomy Faculty Publications
We present a complete set of analytic fits to the nonrelativistic photoionization cross sections for the ground states of atoms and ions of elements from H through Si, and S, Ar, Ca, and Fe. Near the ionization thresholds, the fits are based on the Opacity Project theoretical cross sections interpolated and smoothed over resonances. At higher energies, the fits reproduce calculated Hartree-Dirac-Slater photoionization cross sections.
Mapped Karst Ground-Water Basins In The Lexington 30 X 60 Minute Quadrangle, James C. Currens, Joseph A. Ray
Mapped Karst Ground-Water Basins In The Lexington 30 X 60 Minute Quadrangle, James C. Currens, Joseph A. Ray
Map and Chart--KGS
No abstract provided.
Modeling Transport Of Colloid-Bound Herbicides And Heavy Metals To Groundwater, Anastasios D. Karathanasis, R. E. Phillips, A. K. Seta
Modeling Transport Of Colloid-Bound Herbicides And Heavy Metals To Groundwater, Anastasios D. Karathanasis, R. E. Phillips, A. K. Seta
KWRRI Research Reports
Recent studies have suggested that contaminant transport to groundwater may be enhanced by association with colloidal particles. This study evaluated the role of water dispersible colloids with diverse mineralogical composition in co-transporting selected herbicides and heavy metals through intact soil columns. Colloid recovery in the eluents ranged from 45-90% for the herbicides and 10-60% for the heavy metals. The presence of colloids enhanced the transport of atrazine by 2-18%, and metolachlor by 8-30%. The corresponding increase for Cu and Zn was 2-150 and 5-30 times, respectively. For Pb, there was essentially no elution in the absence of colloids, suggesting nearly …
Formulation Enhanced Transport Of A Soil Applied Herbicide, V. P. Evangelou, Louis M. Mcdonald, Sandra Prima
Formulation Enhanced Transport Of A Soil Applied Herbicide, V. P. Evangelou, Louis M. Mcdonald, Sandra Prima
KWRRI Research Reports
Because pesticides are applied as formulated particles and the affinity of the active ingredient for the formulation is higher than for the bulk water, we hypothesized that a formulation complex could affect active ingredient transport. Our objectives were to investigate the nature and extent of surfactant-atrazine-clay/oxide surface interactions. When atrazine and an anionic surfactant were dried onto plain or Fe-coated sand and leached, atrazine concentrations in the initial leachate were lower in the Fe-coated sand treatment. This was likely due to an electrostatic attraction between the sand and surfactant. When a nonionic surfactant was used, atrazine concentration in the initial …
Metal-Resistance Genetically Engineered Bacteria, Sylvia Daunert, Donna Scott, Sridhar Ramanathan
Metal-Resistance Genetically Engineered Bacteria, Sylvia Daunert, Donna Scott, Sridhar Ramanathan
KWRRI Research Reports
Bacterial-based electrochemical and optical sensing systems that respond in a highly selective and sensitive manner to antimonite and arsenite have been developed. This was accomplished by using genetically engineered bacteria bearing one of two plasmids constructed for our studies. The first plasmid, pBGD23, contains the operator/promoter region (O/P) and the gene of the ArsR protein from the ars operon upstream from the β-galactosidase gene. In the absence of antimonite/arsenite, ArsR binds to the 0/P site and prevents the transcription of the genes for ArsR and β-galactosidase, thus blocking expression of these proteins. When antimonite or arsenite is present in the …
Twig, Branch, And Stem Diseases Of Pine, John R. Hartman
Twig, Branch, And Stem Diseases Of Pine, John R. Hartman
Agriculture and Natural Resources Publications
Tip Blight
Tip blight, caused by the fungus Sphaeropsis sapinea (formerly Diplodia pinea), is a serious disease of mature Austrian, Scots (Scotch), and Mugo pines in Kentucky. In the landscape, tip blight is normally not observed until pines reach about 12 years old and begin to bear cones. Severe infections year after year can greatly weaken and eventually kill affected pines.
Rust Diseases Of Apple, John R. Hartman
Rust Diseases Of Apple, John R. Hartman
Agriculture and Natural Resources Publications
Three related rust diseases occur on apple trees in Kentucky: cedar-apple rust, cedar-hawthorn rust, and cedarquince rust. Crabapple, hawthorn, mountain ash, pear, and serviceberry are also susceptible to these diseases. All three rusts are caused by different species of the fungus Gymnosporangium, each of which must spend a phase of its life cycle as a parasite on Juniperus species such as native red cedars or ornamental junipers.
Although cedar rusts can cause unsightly growths on Juniperus, they do not usually cause serious damage to these plants. Rust diseases can cause serious losses on apples, however, as a result …
Anthracnose Diseases Of Shade Trees, John R. Hartman
Anthracnose Diseases Of Shade Trees, John R. Hartman
Agriculture and Natural Resources Publications
Anthracnose diseases occur on many landscape trees; though, in Kentucky, they tend to be most severe on ash, dogwood, maple, oak, and sycamore. They are typically foliar diseases but twigs, branches, and buds may also be affected. Twigs and branches may develop cankers or dead areas that girdle the stem, causing death of distal parts of the stem. Premature leaf drop commonly occurs on infected trees. Anthracnose is not fatal (except for dogwoods in some circumstances); however, severe defoliation from anthracnose year after year can seriously weaken trees. Weakened trees become more susceptible to environmental stresses and secondary pathogens.
Dogwood …
Maintaining Conventional Septic Systems, William O. Thom, Pat Keefe
Maintaining Conventional Septic Systems, William O. Thom, Pat Keefe
Agriculture and Natural Resources Publications
Septic systems are used in Kentucky where municipal sewage treatment is not available. They are an effective, longstanding method of collecting, treating, and disposing of homeowner wastewater, provided they are properly sited, installed, and maintained. However, a well-sited, properly sized and installed system will fail if not properly maintained. A failed septic system creates problems such as noxious odors, lowered property values, surface water contamination, and groundwater pollution and may be a health hazard. Repair and replacement costs are considerable. Additional information on assessing septic system performance and reducing the potential risk of groundwater contamination is available from a KY-A-Syst …
Very High Density Clumps And Outflowing Winds In Qso Broad-Line Regions, J. A. Baldwin, Gary J. Ferland, K. T. Korista, R. F. Carswell, F. Hamann, M. M. Phillips, D. A. Verner, Belinda J. Wilkes, R. E. Williams
Very High Density Clumps And Outflowing Winds In Qso Broad-Line Regions, J. A. Baldwin, Gary J. Ferland, K. T. Korista, R. F. Carswell, F. Hamann, M. M. Phillips, D. A. Verner, Belinda J. Wilkes, R. E. Williams
Physics and Astronomy Faculty Publications
Intercomparison of the spectra of seven high-luminosity quasi-stellar objects (QSOs) shows that there is a gradation of properties in their broad emission-line regions (BELRs) that can be understood as differing mixtures of different gas components. Six of these seven objects have unusually narrow BELR profiles, which greatly facilitates the disentangling of blends and measuring of weak lines. In the QSO 0207 - 398, the BELR is made up of at least three kinematically distinct components; its spectrum is in fact a composite of the spectra of the more homogeneous BELRs in the QSOs at either end of our sequence of …
High Metal Enrichments In Luminous Quasars, Gary J. Ferland, Jack A. Baldwin, Kirk T. Korista, Fred Hamann, R. F. Carswell, Mark Phillips, Belinda J. Wilkes, Robert E. Williams
High Metal Enrichments In Luminous Quasars, Gary J. Ferland, Jack A. Baldwin, Kirk T. Korista, Fred Hamann, R. F. Carswell, Mark Phillips, Belinda J. Wilkes, Robert E. Williams
Physics and Astronomy Faculty Publications
We discuss observations of the broad emission line in luminous intermediate redshift quasars, with emphasis on Q0207 -398. This object has relatively sharp lines, allowing us to deconvolve the profiles into distinct components. In this paper we examine the high ionization region, which we show must be matter-bounded, partially transparent to ionizing radiation. We measure a large N V λ1240/He II λ1640 ratio in Q0207-398, but detailed calculations predict this ratio to be ~1 for standard cloud properties. We show that no choice of incident continuum, ionizing photon flux, density, or even the appeal to nonradiative energy sources, can reproduce …
The Chemical Enrichment Of Gas In Broad Absorption Line Qsos: Rapid Star Formation In The Early History Of Galaxies, Kirk Korista, Fred Hamann, Jason W. Ferguson, Gary J. Ferland
The Chemical Enrichment Of Gas In Broad Absorption Line Qsos: Rapid Star Formation In The Early History Of Galaxies, Kirk Korista, Fred Hamann, Jason W. Ferguson, Gary J. Ferland
Physics and Astronomy Faculty Publications
Utilizing spectra from ground-based and Hubble Space Telescope observations, Korista et al. identified at least 12 broad absorption lines in the broad absorption line (BAL) QSO 0226-1024 (zem = 2.256), many for the first time. In the present paper we use seven of their measured column densities to investigate the BAL gas ionization equilibrium and metallicity. We assume that the metal abundances follow the rapid star formation (RSF) models of Hamann & Ferland or are simply scaled from solar ratios to (1) limit the free parameters in constraining the overall metallicity and (2) test the applicability of such a …