# Astrophysics and Astronomy Commons™

## All Articles in Astrophysics and Astronomy

2,579 full-text articles. Page 1 of 52.

Rotation Lightcurves Of Small Jovian Trojan Asteroids, 2015 Illinois Wesleyan University

#### Rotation Lightcurves Of Small Jovian Trojan Asteroids, Linda French, Robert D. Stephens, Daniel Coley, Lawrence H. Wasserman, Jennifer Sieben

##### Linda French

Several lines of evidence support a common origin for, and possible hereditary link between, cometary nuclei and Jovian Trojan asteroids. Due to their distance and low albedos, few comet-sized Trojans have been studied. We present new lightcurve information for 19 Trojans ≲ 30 km in diameter, more than doubling the number of objects in this size range for which some rotation information is known. The minimum densities for objects with complete lightcurves are estimated and are found to be comparable to those measured for cometary nuclei. A significant fraction (~40%) of this observed small Trojan population rotates slowly (P > 24 hours ...

2015 Bates College

#### Analysis And Comparison Of Physical Properties And Morphology Of Impact Melt Flows On Venus And The Moon To Determine Atmospheric Controls, Christine Elizabeth Dong

##### Geology Theses

Impact melt flows form when target material melted by an impact breaches the rim of the impact crater. The melt flows out and away from the crater, forming a lava flow. Such flows have been identified on Venus and the Moon by previous studies. This study aims to document impact melt flows on these two bodies to determine the differences, if any, between them, and to ascertain whether these differences are due to atmospheric conditions. Previously recorded morphological data from Robert Herrick of the Lunar and Planetary Institute and Neish et al. (2014) are used in conjunction with S-band (12 ...

Supernatural Cosmic Origins: Challenging The Reigning Paradigm, 2015 Liberty University

#### Supernatural Cosmic Origins: Challenging The Reigning Paradigm, Rachel Blattner

##### Senior Honors Theses

Contemporary scientific study primarily uses a paradigm based upon naturalism, materialism, and empiricism on which to base research. The widely accepted cosmological model the big bang theory adheres to this paradigm. Despite many weaknesses in this model and in the paradigm itself, researchers continue to favor the modification of the accepted model over the adoption of other more comprehensive models. The paradigm from which the models proposed by Russell Humphries, John Hartnett, and Jason Lisle come justifies the six-day creation young-earth biblical account and better fits observational evidence with fewer arbitrary assumptions than the paradigm from which the big bang ...

The Ptolemaic System: A Detailed Synopsis, 2015 Kennesaw State University

#### The Ptolemaic System: A Detailed Synopsis, John Cramer Dr.

##### Oglethorpe Journal of Undergraduate Research

The Ptolemaic System, constructed by Claudius Ptolemeus (the Latin form of his name), was the most influential of all Earth centered cosmological systems. His ingenious and creative work is primarily recorded in his book The Mathematical Systematic Treatise which the Arabs characterized as “the greatest” and, in so doing, gave the book its most used name, Almagest.

The Copernican System: A Detailed Synopsis, 2015 Kennesaw State University

#### The Copernican System: A Detailed Synopsis, John Cramer Dr.

##### Oglethorpe Journal of Undergraduate Research

Dissatisfied with the problems of the geocentric system inherited from Claudius Ptolemy, Nicholas Copernicus began the change from geocentrism to heliocentrism. His eponymous system was expounded first in the Commentariolus (written about 1508 and circulated privately in manuscript form) and then more fully and finally in his book, De Revolutionibus Orbium Coelestium (On the Revolutions of the Celestial Orbs) published as he lay dying in 1543.

2015 The University of Western Ontario

#### Methods And Results Toward Measuring Magnetic Fields In Star-Forming Regions, Scott C. Jones

##### University of Western Ontario - Electronic Thesis and Dissertation Repository

2015 Utah State University

#### The Riemann Curvature Tensor, Its Invariants, And Their Use In The Classification Of Spacetimes, Jesse Hicks

##### Presentations and Publications

The equivalence problem in general relativity is to determine whether two solutions of the Einstein field equations are isometric. Petrov has given a classification of metrics according to their isometry algebras. This talk discusses the use of the Petrov classification scheme, together with the use of scalar curvature invariants, to address the equivalence problem. These are the slides for a presentation at the Mathematics Association of America Spring 2015 conference at Brigham Young University.

2015 Brigham Young University - Provo

#### Radio Emission Toward Regions Of Massive Star Formation In The Large Magellanic Cloud, Adam Johanson

##### All Theses and Dissertations

Four regions of massive star formation in the Large Magellanic Cloud (LMC) were observed for water and methanol maser emission and radio continuum emission. A total of 42 radio detections were made including 27 new radio sources, four water masers, and eight compact HII regions. The lobes of a radio galaxy were resolved for the first time, and the host galaxy identified. Seven sources were associated with known massive young stellar objects (YSOs). A multi-wavelength analysis using both the infrared and radio spectrum was used to characterize the sources. Mid-infrared color-magnitude selection criteria for ultracompact HII (UCHII) regions in the ...

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, 2015 Utah State University

#### Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

##### Presentations and Publications

Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and elec- tromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equa- tions are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Ge- ometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and for- mulas for constructing ...

2015 The University of Western Ontario

#### Rationality Of The Spectral Action For Robertson-Walker Metrics And The Geometry Of The Determinant Line Bundle For The Noncommutative Two Torus, Asghar Ghorbanpour

##### University of Western Ontario - Electronic Thesis and Dissertation Repository

In noncommutative geometry, the geometry of a space is given via a spectral triple $(\mathcal{A,H},D)$. Geometric information, in this approach, is encoded in the spectrum of $D$ and to extract them, one should study spectral functions such as the heat trace $\Tr (e^{-tD^2})$, the spectral zeta function $\Tr(|D|^{-s})$ and the spectral action functional, $\Tr f(D/\Lambda)$.

The main focus of this thesis is on the methods and tools that can be used to extract the spectral information. Applying the pseudodifferential calculus and the heat trace techniques, in addition to computing the newer ...

2015 Cleveland State University

#### On The Detection Of Exoplanets Via Radial Velocity Doppler Spectroscopy, Joseph P. Glaser

##### The Downtown Review

Since the discovery of the first exoplanet occurred in the late 1980s, physicists and astronomers have confirmed the existence of over 1783 planets orbiting other stars. Over the years, several methods have been developed for detecting these celestial systems, but none has thus far been more successful than the use of Radial Velocity Doppler Spectroscopy. As such, this paper attempts to break down the barriers placed before new entries into the field by detailing the theoretical premise and experimental process of this most successful technique. The content enclosed is geared for the senior undergraduate student with some knowledge of vector-based ...

The Formation Of The Trajectories Of The Planets Of The Solar System, 2015 Yanbikov Vildyan Shavkyatovich

#### The Formation Of The Trajectories Of The Planets Of The Solar System, Vildyan Yanbikov

##### Vildyan Yanbikov

Процесс превращения круговой орбите планеты по эллиптической. Процесс превращения эллиптической орбите вокруг Солнца (прецессия перигелия планеты).

Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, 2015 Department of Physics, Utah State University

#### Geometrization Conditions For Perfect Fluids, Scalar Fields, And Electromagnetic Fields, Charles G. Torre, Dionisios Krongos

##### Charles G. Torre

Rainich-type conditions giving a spacetime “geometrization” of matter fields in general relativity are reviewed and extended. Three types of matter are considered: perfect fluids, scalar fields, and elec- tromagnetic fields. Necessary and sufficient conditions on a spacetime metric for it to be part of a perfect fluid solution of the Einstein equa- tions are given. Formulas for constructing the fluid from the metric are obtained. All fluid results hold for any spacetime dimension. Ge- ometric conditions on a metric which are necessary and sufficient for it to define a solution of the Einstein-scalar field equations and for- mulas for constructing ...

Alignment Of The Western And Eastern Passage Tombs At Knowth Tomb 1, 2015 Dublin Institute of Technology

#### Alignment Of The Western And Eastern Passage Tombs At Knowth Tomb 1, Frank Prendergast, Tom Ray

##### Book/Book Chapter

This report presents a summary account of two surveys undertaken by the authors to determine and interpret the alignments of the western and eastern passage tombs at Knowth, Co. Meath. The findings indicate that contrary to earlier suggestions, the eastern passage and the western passage (inner and outer) are not aligned towards sunrise and sunset respectively at the period of the vernal and autumnal equinoxes.

Rainich-Type Conditions For Perfect Fluid Spacetimes, 2014 Utah State University

#### Rainich-Type Conditions For Perfect Fluid Spacetimes, Dionisios Krongos, Charles G. Torre

##### Research Vignettes

In this worksheet we describe and illustrate a relatively simple set of new Rainich-type conditions on an n-dimensional spacetime which are necessary and sufficient for it to define a perfect fluid solution of the Einstein field equations. Procedures are provided which implement these Rainich-type conditions and which reconstruct the perfect fluid from the metric. These results provide an example of the idea of geometrization of matter fields in general relativity, which is a purely geometrical characterization of matter fields via the Einstein field equations.

Star Cluster Populations In Compact Groups Of Galaxies, 2014 The University of Western Ontario

#### Star Cluster Populations In Compact Groups Of Galaxies, Konstantin Fedotov

##### University of Western Ontario - Electronic Thesis and Dissertation Repository

In this thesis, I have explored the star cluster populations of several compact groups of galaxies, based on observations with the Advanced Camera for Surveys and the Wide Field Camera 3 on the Hubble Space Telescope. Low velocity dispersions and high galaxy number densities, the conditions of compact groups (in particular Hickson Compact Groups), represent an environment with frequent and prolonged interactions. Such environment can trigger the formation of star cluster populations associated with specific events. The BVI study has shown that star clusters can be used as a powerful tool for studying such events triggered by mergers and tidal ...

2014 The University of Western Ontario

#### Scale-Up Methodology For Bench-Scale Slurry Photocatalytic Reactors Using Combined Irradiation And Kinetic Modelling, Patricio J. Valades Pelayo

##### University of Western Ontario - Electronic Thesis and Dissertation Repository

The present study focuses on developing a predictive methodology to scale-up a slurry annular photoreactor using a TiO2 Degussa P25 from the bench-scale to a pilot-plant scale. The bench-scale photoreactor is a Photo-CREC-Water II, a 2.65 L internally-irradiated slurry annular photocatalytic reactor. The pilot-plant scale photoreactor is a Photo-CREC Water Solar Simulator, a 9.8 L pilot-plant photoreactor, externally irradiated by eight lamps.

The adopted methodology allows the independent validation of radiative and kinetic models avoiding cross-correlation issues. The proposed approach involves two Monte Carlo methods, to model the Radiative Transfer Equation (RTE) inside each photoreactor. With this ...

Should We Love Or Hate Big Data? The Good, The Bad, And The Ugly, 2014 La Salle University

#### Should We Love Or Hate Big Data? The Good, The Bad, And The Ugly, Dennis Crossen M.Sc., Mba, Karti Puranam Phd, Madjid Tavana Phd

##### Explorer Café

No abstract provided.

The Optical Luminosity Function Of Gamma-Ray Bursts Deduced From Rotse-Iii Observations, 2014 College of Saint Benedict/Saint John's University

#### The Optical Luminosity Function Of Gamma-Ray Bursts Deduced From Rotse-Iii Observations, X. H. Cui, X. F. Wu, J. J. Wei, F. Yuan, W. K. Zheng, E. W. Liang, C. W. Akerlof, M. C. B. Ashley, H A. Flewelling, E. Göǧüş, T. Güver, Ü. Kızıloǧlu, T. A. Mckay, S. B. Pandey, E. S. Rykoff, W. Rujopakarn, B. E. Schaefer, J. C. Wheeler, Sarah A. Yost

##### Physics Faculty Publications

We present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of 58 GRBs from observations with the Robotic Optical Transient Search Experiment III (ROTSE-III). Our GRB sample is divided into two sub-samples: detected afterglows (18 GRBs) and those with upper limits (40 GRBs). We derive R-band fluxes for these two sub-samples 100 s after the onset of the burst. The optical LFs at 100 s are fitted by assuming that the co-moving GRB rate traces the star formation rate. While fitting the optical LFs using Monte Carlo simulations, we take into account the ...

Nasa's Search For Life Beyond The Earth, 2014 UAlbany

#### Nasa's Search For Life Beyond The Earth, John W. Delano Prof

##### Department of Atmospheric and Environmental Science Faculty Scholarship

Invited presentation (November 3, 2014 for the 119th Annual Conference of the Science Teachers Association of New York State) provides an overview of NASA's search for worlds orbiting other nearby stars on the Milky Way galaxy.