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Articles 151 - 180 of 307

Full-Text Articles in Astrophysics and Astronomy

Conference Review ‘’The Astronomy In Skyscapes - Archaeoastronomy Beyond Alignments’’. Full Day Session At The National Astronomy Meeting, University Of Nottingham (United Kingdom), 27th June–1st July, 2016, Frank Prendergast Jan 2017

Conference Review ‘’The Astronomy In Skyscapes - Archaeoastronomy Beyond Alignments’’. Full Day Session At The National Astronomy Meeting, University Of Nottingham (United Kingdom), 27th June–1st July, 2016, Frank Prendergast

Articles

The National Astronomy Meeting (NAM) of the Royal Astronomical Society (RAS) was held at the University of Nottingham Jubilee Campus on 27th June–1st July, 2016. This event is the primary annual scientific conference for astronomers and space scientists drawn mainly from the UK and Ireland. It is sponsored and coordinated by RAS. NAM 2016 had eight plenary talks spanning topics from planets to cosmology. Additionally, there were 60 parallel sessions broadly split into five themes, one of which was archaeoastronomy. This was the third successive NAM conference to feature a parallel session on archaeoastronomy, and was organised and chaired by …


Mayo Dark Skies Park: A Virtual Experience, Mayo Dark Skies Community Group, Frank Prendergast Jan 2017

Mayo Dark Skies Park: A Virtual Experience, Mayo Dark Skies Community Group, Frank Prendergast

Datasets

The Mayo Dark Skies Community Group, in collaboration with the Dublin Institution of Technology, is pleased to launch a digital virtual experience of the Mayo Dark Sky Park. Following its designation as an International Dark Sky Park (Gold Tier), it is now possible to experience a part of this magnificent and pristine skyscape on your computer. This has been made possible using open source software (Stellarium http://www.stellarium.org/) and a specially commissioned digital panorama of the horizon surrounding the Ballycroy National Park Visitor Centre.

Stellarium is an open source planetarium for your computer and shows a fully realistic …


Search For High-Energy Gamma Rays In The Northern Fermi Bubble Region With The Hawc Observatory, Hugo Alberto Ayala Solares Jan 2017

Search For High-Energy Gamma Rays In The Northern Fermi Bubble Region With The Hawc Observatory, Hugo Alberto Ayala Solares

Dissertations, Master's Theses and Master's Reports

Gamma-ray astronomy is the study of very energetic photons, from E = mec2 = 0.5x106 eV to > 1020eV. Due to the large span of the energy range, the field focuses on non-thermal processes that include the acceleration and propagation of relativistic particles, which can be found in extreme environments such as pulsars, supernova remnants, molecular clouds, black holes, etc.

The High Altitude Water Cherenkov (HAWC) observatory is an instrument designed for the study of gamma rays in the energy range of 100 GeV to 100 TeV. Using data from the HAWC observatory, a study …


Investigating The Impact Of Unsupervised Feature-Extraction From Multi-Wavelength Image Data For Photometric Classification Of Stars, Galaxies And Qsos, Annika Lindh Dec 2016

Investigating The Impact Of Unsupervised Feature-Extraction From Multi-Wavelength Image Data For Photometric Classification Of Stars, Galaxies And Qsos, Annika Lindh

Conference papers

Accurate classification of astronomical objects currently relies on spectroscopic data. Acquiring this data is time-consuming and expensive compared to photometric data. Hence, improving the accuracy of photometric classification could lead to far better coverage and faster classification pipelines. This paper investigates the benefit of using unsupervised feature-extraction from multi-wavelength image data for photometric classification of stars, galaxies and QSOs. An unsupervised Deep Belief Network is used, giving the model a higher level of interpretability thanks to its generative nature and layer-wise training. A Random Forest classifier is used to measure the contribution of the novel features compared to a set …


Exoplanet Research: Differential Photometry For Kepler 6b, Garrett T. Benson, Charlotte Alexandra Olsen Oct 2016

Exoplanet Research: Differential Photometry For Kepler 6b, Garrett T. Benson, Charlotte Alexandra Olsen

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

No abstract provided.


Optimizing The Telescope Assembly Alignment Simulator For Sofia, Zoe E. Sharp, Alex Quyenvo, Jennifer Briggs, Brian Eney Oct 2016

Optimizing The Telescope Assembly Alignment Simulator For Sofia, Zoe E. Sharp, Alex Quyenvo, Jennifer Briggs, Brian Eney

STAR Program Research Presentations

The Stratospheric Observatory for Infrared Astronomy (SOFIA) conducts research on a modified Boeing 747sp aircraft. By using a variety of infrared science instruments mounted on a 2.7 meter telescope, researchers can make discoveries about the galactic center, star formation, and various topics associated with a deeper understanding of our universe. To efficiently collect data through the SOFIA instruments, the instruments must be tested and prepared prior to being placed on the aircraft. Therefore, with the use of the Telescope Assembly Alignment Simulator (TAAS), researchers can design and construct improvements needed for these instruments to efficiently perform while in flight. The …


Book Review: The International Atlas Of Mars Exploration: From Spirit To Curiosity: V.2: 2004 To 2014, T. D. Oswalt Oct 2016

Book Review: The International Atlas Of Mars Exploration: From Spirit To Curiosity: V.2: 2004 To 2014, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The International Atlas of Mars Exploration: from Spirit to Curiosity : V.2: 2004 to 2014 by Philip J. Stooke. 444p bibl index, 9781107030930 $145.00, 9781139344470 LC Call Number: 1000


Investigating The Impact Of Unsupervised Feature-Extraction From Multi-Wavelength Image Data For Photometric Classification Of Stars, Galaxies And Qsos, Annika Lindh Sep 2016

Investigating The Impact Of Unsupervised Feature-Extraction From Multi-Wavelength Image Data For Photometric Classification Of Stars, Galaxies And Qsos, Annika Lindh

Dissertations

This thesis reviews the current state of photometric classification in Astronomy and identifies two main gaps: a dependence on handcrafted rules, and a lack of interpretability in the more successful classifiers. To address this, Deep Learning and Computer Vision were used to create a more interpretable model, using unsupervised training to reduce human bias.

The main contribution is the investigation into the impact of using unsupervised feature-extraction from multi-wavelength image data for the classification task. The feature-extraction is achieved by implementing an unsupervised Deep Belief Network to extract lower-dimensionality features from the multi-wavelength image data captured by the Sloan Digital …


Book Review: How Do You Find An Exoplanet?, T. D. Oswalt Sep 2016

Book Review: How Do You Find An Exoplanet?, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of How Do You Find an Exoplanet? by John Asher Johnson. Princeton, 2016 178p bibl index afp, 9780691156811 $35.00, 9781400873999


Flickering Analysis Of Ch Cygni Using Kepler Data, Thomas Holden Dingus Aug 2016

Flickering Analysis Of Ch Cygni Using Kepler Data, Thomas Holden Dingus

Undergraduate Honors Theses

Utilizing data from the Kepler Mission, we analyze a flickering phenomenon in the symbiotic variable star CH Cygni. We perform a spline interpolation of an averaged lightcurve and subtract the spline to acquire residual data. This allows us to analyze the deviations that are not caused by the Red Giant’s semi-regular periodic variations. We then histogram the residuals and perform moment calculations for variance, skewness, and kurtosis for the purpose of determining the nature of the flickering. Our analysis has shown that we see a much smaller scale flickering than observed in the previous literature. Our flickering scale is on …


Back Half Of The Year, Ian R. Clarke Jul 2016

Back Half Of The Year, Ian R. Clarke

Physics and Astronomy Faculty Publications

Here we are in the back half of 2016, and the days are getting shorter. We have, as of today, lost 18 minutes since the solstice on June 20, and the speed of that change is quickening. You may wonder why it is that we have our hottest weather after our longest day is behind us. The simple answer is that it takes time for land and water masses to warm up. That’s the reason that Sept. 21 is likely to be a lot warmer than March 21, even though they have the same amount of daylight. [excerpt]


Living In The Milky Way, Ian R. Clarke Jun 2016

Living In The Milky Way, Ian R. Clarke

Physics and Astronomy Faculty Publications

It’s finally here. Today, June 20 at 6:34 p.m., is the the summer solstice, also known as the first day of summer and, confusingly enough, midsummer’s eve. From a scientific perspective, it marks the moment the sun reaches its northernmost point in our sky. As a result of that position, it’s the shortest night and longest day if you live north of the equator. [excerpt]


Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy Jun 2016

Analytic Models Of Brown Dwarfs And The Substellar Mass Limit, Sree Ram Valluri, Shantanu Basu, Sayantan Auddy

Physics and Astronomy Publications

We present the analytic theory of brown dwarf evolution and the lower mass limit of the hydrogen burning main-sequence stars and introduce some modifications to the existing models. We give an exact expression for the pressure of an ideal nonrelativistic Fermi gas at a finite temperature, therefore allowing for nonzero values of the degeneracy parameter. We review the derivation of surface luminosity using an entropy matching condition and the first-order phase transition between the molecular hydrogen in the outer envelope and the partially ionized hydrogen in the inner region.We also discuss the results of modern simulations of the plasma phase …


Medieval Cosmology And Middle-Earth: A Lewisian Walk Under Tolkienian Skies, Kristine Larsen May 2016

Medieval Cosmology And Middle-Earth: A Lewisian Walk Under Tolkienian Skies, Kristine Larsen

Journal of Tolkien Research

A nearly identical version of this paper was delivered at the 30th Annual International Conference on Medievalism in Pittsburgh, Pennsylvania on October 2, 2015, as part of a session on the Inklings and Medievalism.


Book Review: Moons Of The Solar System: From Giant Ganymede To Dainty Dactyl, T. D. Oswalt Apr 2016

Book Review: Moons Of The Solar System: From Giant Ganymede To Dainty Dactyl, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Moons of the Solar System : from Giant Ganymede to Dainty Dactyl by James A. Hall, III. Springer 2015. 297p index afp, 9783319206356 $34.99, 9783319206363 $19.99


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 …


Astr 103: Descriptive Astronomy Syllabus, Michael Sibbernsen Oct 2015

Astr 103: Descriptive Astronomy Syllabus, Michael Sibbernsen

Department of Physics and Astronomy: Syllabi

Syllabus for ASTR 103 Descriptive Astronomy for Fall 2015 semester.


Astr 224: Astronomy And Astrophysics Laboratory, Zachary Smith Oct 2015

Astr 224: Astronomy And Astrophysics Laboratory, Zachary Smith

Department of Physics and Astronomy: Syllabi

Syllabus for ASTR 224 Astronomy and Astrophysics Laboratory for Fall 2015.


Astr 204: Introduction To Astronomy And Astrophysics, Shawn Langan Oct 2015

Astr 204: Introduction To Astronomy And Astrophysics, Shawn Langan

Department of Physics and Astronomy: Syllabi

Syllabus for ASTR 204 Introduction to Astronomy and Astrophysics for Fall 2015 semester.


Astr 113: Life In The Universe Syllabus, Edward Schmidt Oct 2015

Astr 113: Life In The Universe Syllabus, Edward Schmidt

Department of Physics and Astronomy: Syllabi

Syllabus for ASTR 113 Life in the Universe for Fall 2015 semester.


Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt Sep 2015

Ultraviolet Luminosity Density Of The Universe During The Epoch Of Reionization, Ketron Mitchell-Wynne, Asantha Cooray, Yan Gong, Matthew Ashby, Timothy Dolch, Henry Ferguson, Steven Finkelstein, Norman Grogin, Dale D. Kocevski, Anton Koekemoer, Joel Primack, Joseph Smidt

Physics and Astronomy Faculty Publications

The spatial fluctuations of the extragalactic background light trace the total emission from all stars and galaxies in the Universe. A multiwavelength study can be used to measure the integrated emission from first galaxies during reionization when the Universe was about 500 million years old. Here we report arcmin-scale spatial fluctuations in one of the deepest sky surveys with the Hubble Space Telescope in five wavebands between 0.6 and 1.6 μm. We model-fit the angular power spectra of intensity fluctuation measurements to find the ultraviolet luminosity density of galaxies at redshifts greater than 8 to be log ρUV = …


Book Review: The Scientific Exploration Of Venus, T. D. Oswalt Jun 2015

Book Review: The Scientific Exploration Of Venus, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Scientific Exploration of Venus, by Fredric W. Taylor. Cambridge, 2014 295p bibl index, 9781107023482 $48.00


Detection Of Baryonic Acoustic Oscillations In The Matter Power Spectrum, Spencer Everett, Ian Johnson, Jon Murphy, Mary Tarpley May 2015

Detection Of Baryonic Acoustic Oscillations In The Matter Power Spectrum, Spencer Everett, Ian Johnson, Jon Murphy, Mary Tarpley

DePaul Discoveries

Using the spectra of 22,923 high-redshift quasars from the Baryon Oscillation Spectrosocpic Survey (BOSS) subset of the Sloan Digital Sky Survey (SDSS), the authors detect evidence of the primordial baryonic acoustic oscillations (BAOs) in the matter power spectrum. The detection further endorses the currently accepted Lambda-CDM model of cosmology based upon the existence of dark energy (Lambda) and cold dark matter (CDM). Additionally, the use of the continuous wavelet transform to calculate the power spectrum has many advantages over traditional Fourier methods and independently corroborates previous detections.


Gravitational Wave Background In The Quasi-Steady State Cosmology, Sree Ram Valluri, Sayantan Auddy, J V. Narlikar, S V. Dhurandhar, R G. Vishwakarma Apr 2015

Gravitational Wave Background In The Quasi-Steady State Cosmology, Sree Ram Valluri, Sayantan Auddy, J V. Narlikar, S V. Dhurandhar, R G. Vishwakarma

Physics and Astronomy Publications

This paper calculates the expected gravitational wave background (GWB) in the quasi-steady state cosmology (QSSC). The principal sources of gravitational waves in the QSSC are the mini-creation events (MCE). With suitable assumptions the GWB can be computed both numerically and with analytical methods. It is argued that the GWB in QSSC differs from that predicted for the standard cosmology and a future technology of detectors will be able to decide between the two predictions. We also derive a formula for the flux density of a typical extragalactic source of gravitational waves.


The Ptolemaic System: A Detailed Synopsis, John Cramer Dr. Apr 2015

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.


Elastic Waves Along A Fracture Intersection, Bradley C. Abell Apr 2015

Elastic Waves Along A Fracture Intersection, Bradley C. Abell

Open Access Dissertations

Fractures and fracture networks play a significant role in the subsurface hydraulic connectivity within the Earth. While a significant amount of research has been performed on the seismic response of single fractures and sets of fractures, few studies have examined the effect of fracture intersections on elastic wave propagation. Intersections play a key role in the connectivity of a fracture network that ultimately affects the hydraulic integrity of a rock mass. In this dissertation two new types of coupled waves are examined that propagate along intersections. 1) A coupled wedge wave that propagates along a surface fracture with particle motion …


On The Detection Of Exoplanets Via Radial Velocity Doppler Spectroscopy, Joseph P. Glaser Jan 2015

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

The Downtown Review: An Interdisciplinary Journal Written and Peer-Reviewed by Mandel Honors College Students at Cleveland State University

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 …


Building A Scalable Global Data Processing Pipeline For Large Astronomical Photometric Datasets, Paul Doyle Jan 2015

Building A Scalable Global Data Processing Pipeline For Large Astronomical Photometric Datasets, Paul Doyle

Other

Astronomical photometry is the science of measuring the flux of a celestial object. Since its introduction, the CCD has been the principle method of measuring flux to calculate the apparent magnitude of an object. Each CCD image taken must go through a process of cleaning and calibration prior to its use. As the number of research telescopes increases the overall computing resources required for image processing also increases. Existing processing techniques are primarily sequential in nature, requiring increasingly powerful servers, faster disks and faster networks to process data. Existing High Performance Computing solutions involving high capacity data centres are complex …


Book Review: Planetary Rings: A Post-Equinox View 2nd Ed, T. D. Oswalt Nov 2014

Book Review: Planetary Rings: A Post-Equinox View 2nd Ed, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Planetary Rings : a Post-Equinox View 2nd Ed. by Larry W. Esposito, Cambridge, 2014 246p bibl index, 9781107028821 $120.00


Revised Age For Cm Draconis And Wd 1633+ 572-Toward A Resolution Of Model-Observation Radius Discrepancies, Gregory A. Feiden, Brian Chaboyer Sep 2014

Revised Age For Cm Draconis And Wd 1633+ 572-Toward A Resolution Of Model-Observation Radius Discrepancies, Gregory A. Feiden, Brian Chaboyer

Dartmouth Scholarship

We report an age revision for the low-mass detached eclipsing binary CM Draconis and its common proper motion companion, WD 1633+572. An age of 8.5 +/- 3.5 Gyr is found by combining an age estimate for the lifetime of WD 1633+572 and an estimate from galactic space motions. The revised age is greater than a factor of two older than previous estimates. Our results provide consistency between the white dwarf age and the system's galactic kinematics, which reveal the system is a highly probable mem