Open Access. Powered by Scholars. Published by Universities.®

Astrophysics and Astronomy Commons

Open Access. Powered by Scholars. Published by Universities.®

8,853 Full-Text Articles 23,801 Authors 2,672,995 Downloads 207 Institutions

All Articles in Astrophysics and Astronomy

Faceted Search

8,853 full-text articles. Page 217 of 308.

Astronomy 101 Online The Solar System Summer 2015, Pam Friese 2015 Parkland College

Astronomy 101 Online The Solar System Summer 2015, Pam Friese

Astronomy Courses

No abstract provided.


Orion, Teresa M. Boerma 2015 Parkland College

Orion, Teresa M. Boerma

Natural Sciences Student Research Presentations

The purpose of this project was to gather information about the stars and objects in the constellation Orion. This is a project for the Natural Sciences Poster Session at Parkland College.


Feldspathic Rocks On Mars: Compositional Constraints From Infrared Spectroscopy And Possible Formation Mechanisms, Deanne Rogers, Hanna Nekvasil 2015 SUNY Stony Brook

Feldspathic Rocks On Mars: Compositional Constraints From Infrared Spectroscopy And Possible Formation Mechanisms, Deanne Rogers, Hanna Nekvasil

Department of Geosciences Faculty Publications

Rare feldspar-dominated surfaces on Mars were previously reported based on near-infrared (NIR) spectral data and were interpreted to consist of anorthosite or felsic rocks. Using thermal infrared (TIR) data over the feldspar detections with the largest areal extent in Nili Patera and Noachis Terra, we rule out felsic interpretations. Basaltic or anorthositic compositions are consistent with TIR measurements, but the geologic contexts for these regions do not support a plutonic origin. Laboratory NIR spectral measurements demonstrate that large plagioclase crystals (>~840 μm) can be detected in mixtures with as much as 50 vol % mafics, which is higher than …


Dye Distance Mapping Using Waveguide Evanescent Field Fluorescence Microscopy And Its Application To Cell Biology, Frederik Fleissner, Michael Morawitz, S. Jeffrey Dixon, Uwe Langbein, Silvia Mittler 2015 Western University

Dye Distance Mapping Using Waveguide Evanescent Field Fluorescence Microscopy And Its Application To Cell Biology, Frederik Fleissner, Michael Morawitz, S. Jeffrey Dixon, Uwe Langbein, Silvia Mittler

Physics and Astronomy Publications

Previous studies have measured the distance between cells and the substratum at sites of adhesion via the emission of a fluorescent dye and waveguide methods. Here, we demonstrate a novel approach to measure the position of fluorescent dyes above a waveguide surface in the 10-200 nm distance range throughout an entire area, yielding a 2D dye distance map or a 3D contour plot. The dye is located in a multilayered Langmuir Blodgett (LB) film or in the plasma membrane of a cell. Waveguide evanescent field fluorescence (WEFF) images obtained using two different waveguide modes are employed allowing, with a simple …


Cavity Ignition In Supersonic Flow By Spark Discharge And Pulse Detonation, Timothy M. Ombrello, Campbell D. Carter, Chung-Jen Tam, Kuang-Yu Hsu 2015 Wright-Patterson Air Force Base

Cavity Ignition In Supersonic Flow By Spark Discharge And Pulse Detonation, Timothy M. Ombrello, Campbell D. Carter, Chung-Jen Tam, Kuang-Yu Hsu

United States Air Force: Publications

Ignition of an ethylene fueled cavity in a supersonic flow was achieved through the application of two energy deposition techniques: a spark discharge and pulse detonator (PD). High-frequency shadowgraph and chemiluminescence imaging showed that the spark discharge ignition was passive with the ignition kernel and ensuing flame propagation following the cavity flowfield. The PD produced a high-pressure and temperature exhaust that allowed for ignition at lower tunnel temperatures and pressures than the spark discharge, but also caused significant disruption to the cavity flowfield dynamics. Under certain cavity fueling conditions a multiple regime ignition process occurred with the PD that led …


Characterizing Exoplanet Atmospheres: From Light-Curve Observations To Radiative-Transfer Modeling, Patricio Cubillos Vallejos 2015 University of Central Florida

Characterizing Exoplanet Atmospheres: From Light-Curve Observations To Radiative-Transfer Modeling, Patricio Cubillos Vallejos

Electronic Theses and Dissertations

Multi-wavelength transit and secondary-eclipse light-curve observations are some of the most powerful techniques to probe the thermo-chemical properties of exoplanets. Although the large planet-to-star brightness contrast and few available spectral bands produce data with low signal-to-noise ratios, a Bayesian approach can robustly reveal what constraints we can set, without over-interpreting the data. Here I performed an end-to-end analysis of transiting exoplanet data. I analyzed space-telescope data for three planets to characterize their atmospheres and refine their orbits, investigated correlated noise estimators, and contributed to the development of the respective data-analysis pipelines. Chapters 2 and 3 describe the Photometry for Orbits, …


Four Color Observations Of 2501 Lohja, Bin Li, Haibin Zhao, Hao Lu, Xianming Han 2015 Butler University

Four Color Observations Of 2501 Lohja, Bin Li, Haibin Zhao, Hao Lu, Xianming Han

Scholarship and Professional Work - LAS

Photometric studies of asteroid 2501 Lohja were made between 2014 June 24 and 25 using the Southeastern Association for Research in Astronomy (SARA) Kitt Peak telescope with Bessell B, V, R and I filters. We obtained a synodic period of 3.81 ± 0.01h, which is consistent with previous values.


A Fast Visible Infrared Imaging Radiometer Suite Simulator For Cloudy Atmospheres, Chao Liu, Ping Yang, Steven Platnick, Kerry G. Meyer, Chenxi Wang, Shouguo Ding 2015 Texas A&M University

A Fast Visible Infrared Imaging Radiometer Suite Simulator For Cloudy Atmospheres, Chao Liu, Ping Yang, Steven Platnick, Kerry G. Meyer, Chenxi Wang, Shouguo Ding

Department of Earth and Atmospheric Sciences: Faculty Publications

A fast instrument simulator is developed to simulate the observations made in cloudy atmospheres by the Visible Infrared Imaging Radiometer Suite (VIIRS). The correlated k distribution technique is used to compute the transmissivities associated with absorbing atmospheric gases. The bulk scattering properties of ice clouds are based on the ice model used for the Moderate Resolution Imaging Spectroradiometer Collection 6 ice cloud products, and those ofwater clouds are computedwith the Lorenz-Mie theory. Two fast radiative transfer models based on precomputed ice cloud look-up tables are used for the VIIRS solar and infrared channels. The accuracy and efficiency of the fast …


The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. McIntosh, A. van der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth 2015 University of Kentucky

The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. Mcintosh, A. Van Der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth

Physics and Astronomy Faculty Publications

We study the relationship between the structure and star formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies, which we then compare to those of the AGNs. At z ~ 1, AGNs show slightly diskier light profiles than massive inactive (non-AGN) galaxies, as well as modestly higher levels …


Experimental Simulations Of Recurring Slope Lineae On The Surface Of Mars, Elizabeth Eddings 2015 Connecticut College

Experimental Simulations Of Recurring Slope Lineae On The Surface Of Mars, Elizabeth Eddings

Physics, Astronomy and Geophysics Honors Papers

Recurring Slope Lineae (RSL) are active surface features found on rocky Martian slopes commonly in the southern hemisphere equatorial to mid-latitude regions. These low albedo, dark streaks on Mars demonstrate seasonal characteristics;; they appear and grow darker and longer in warm months and fade to possible disappearance in colder months. One proposed mechanism for the formation and evolution of these features by McEwen et al. (2011) is the melting of subsurface water on Mars. The goal of this study was to test this hypothesis by reconstructing features similar to RSL in the lab that display the same seasonal …


Detection Of Temporal Changes In Vegetative Cover On South Padre Island, Texas Using Image Classifications Derived From Aerial Color-Infrared Photographs, Ruben A. Mazariegos, Kenneth R. Summy, Frank W. Judd, Robert I. Lonard, James H. Everitt 2015 The University of Texas Rio Grande Valley

Detection Of Temporal Changes In Vegetative Cover On South Padre Island, Texas Using Image Classifications Derived From Aerial Color-Infrared Photographs, Ruben A. Mazariegos, Kenneth R. Summy, Frank W. Judd, Robert I. Lonard, James H. Everitt

Physics & Astronomy Faculty Publications

Supervised image classifications developed from 23 x 23 cm aerial color-infrared aerial photographs (1:5,000 scale) were used to evaluate temporal changes in vegetative cover occurring within three 150 x 300-m research sites on South Padre Island, Texas. Use of high-resolution digitized imagery (ground pixel resolution of ca. 0.1 m) and survey-grade GPS for positional measurements of ground control points (20-25 1.0m2 targets within each research site) resulted in consistently high levels of geometric accuracy, with root mean square errors (RMSEs) ranging between 0.397 – 2.867. Similarly, use of relatively simple information categories (dry and wet sand, live and dead vegetative …


An Ion Detector For The Array For Nuclear Astrophysics And Structure With Exotic Nuclei (Anasen), Cedric Williams, K Macon, C M. Deibel, J C. Blackmon 2015 Louisiana State University

An Ion Detector For The Array For Nuclear Astrophysics And Structure With Exotic Nuclei (Anasen), Cedric Williams, K Macon, C M. Deibel, J C. Blackmon

Honors Capstones

No abstract provided.


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

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 …


Study Solar Activity In The Backside Of The Sun With The Stereo Mission, Catherine A. Gibbs 2015 University of Alabama in Huntsville

Study Solar Activity In The Backside Of The Sun With The Stereo Mission, Catherine A. Gibbs

Summer Community of Scholars Posters (RCEU and HCR Combined Programs)

No abstract provided.


Koi-3158: The Oldest Known System Of Terrestrial-Size Planets, Tiago L. Campante, Darin A. Ragozzine 2015 University of Birmingham

Koi-3158: The Oldest Known System Of Terrestrial-Size Planets, Tiago L. Campante, Darin A. Ragozzine

Aerospace, Physics, and Space Science Faculty Publications

The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii) can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts …


Koi-3158: The Oldest Known System Of Terrestrial-Size Planets, Tiago L. Campante, Darin A. Ragozzine 2015 University of Birmingham

Koi-3158: The Oldest Known System Of Terrestrial-Size Planets, Tiago L. Campante, Darin A. Ragozzine

Aerospace, Physics, and Space Science Faculty Publications

The first discoveries of exoplanets around Sun-like stars have fueled efforts to find ever smaller worlds evocative of Earth and other terrestrial planets in the Solar System. While gas-giant planets appear to form preferentially around metal-rich stars, small planets (with radii less than four Earth radii) can form under a wide range of metallicities. This implies that small, including Earth-size, planets may have readily formed at earlier epochs in the Universe's history when metals were far less abundant. We report Kepler spacecraft observations of KOI-3158, a metal-poor Sun-like star from the old population of the Galactic thick disk, which hosts …


Search For Dark Photons From Neutral Meson Decays In P+P And D+ Au Collisions At √Snn =200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, PHENIX Collaboration 2015 University of Colorado, Boulder

Search For Dark Photons From Neutral Meson Decays In P+P And D+ Au Collisions At √Snn =200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Phenix Collaboration

Aerospace, Physics, and Space Science Faculty Publications

The standard model (SM) of particle physics is spectacularly successful, yet the measured value of the muon anomalous magnetic moment (g-2)μ deviates from SM calculations by 3.6σ. Several theoretical models attribute this to the existence of a "dark photon," an additional U(1) gauge boson, which is weakly coupled to ordinary photons. The PHENIX experiment at the Relativistic Heavy Ion Collider has searched for a dark photon, U, in π0,η→γe+e- decays and obtained upper limits of O(2×10‐⁶) U-γ mixing at 90% C.L. for the mass range 30< mᵤ < 90 MeV/c². Combined with other experimental limits, the remaining region in the U-γ mixing parameter space that can explain the (g-2)ᵤ deviation from its SM value is nearly completely excluded at the 90% confidence level, with only a small region of 29


Evidence For Transverse-Momentum- And Pseudorapidity-Dependent Event-Plane Fluctuations In Pbpb And P Pb Collisions, Vardan Khachatryan, Vallary Bhopatkar, Marcus Hohlmann, H. Kalakhety, D. Mareskas-Palcek, Tuhin S. Roy, Francisco X. Yumiceva, CMS Collaboration 2015 Yerevan Physics Institute

Evidence For Transverse-Momentum- And Pseudorapidity-Dependent Event-Plane Fluctuations In Pbpb And P Pb Collisions, Vardan Khachatryan, Vallary Bhopatkar, Marcus Hohlmann, H. Kalakhety, D. Mareskas-Palcek, Tuhin S. Roy, Francisco X. Yumiceva, Cms Collaboration

Aerospace, Physics, and Space Science Faculty Publications

A systematic study of the factorization of long-range azimuthal two-particle correlations into a product of single-particle anisotropies is presented as a function of pT and η of both particles and as a function of the particle multiplicity in PbPb and pPb collisions. The data were taken with the CMS detector for PbPb collisions at sNN=2.76 TeV and pPb collisions at sNN=5.02 TeV, covering a very wide range of multiplicity. Factorization is observed to be broken as a function of both particle pT and η. When measured with particles of different pT, the magnitude of the factorization breakdown for the second …


Φ Meson Production In D + Au Collisions At √Snn =200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Phenix Collaboration 2015 University of Colorado, Boulder

Φ Meson Production In D + Au Collisions At √Snn =200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Phenix Collaboration

Aerospace, Physics, and Space Science Faculty Publications

The PHENIX Collaboration has measured φ meson production in d+Au collisions at √sNN=200 GeV using the dimuon and dielectron decay channels. The φ meson is measured in the forward (backward) d-going (Au-going) direction, 1.2 < y < 2.2 (-2.2 < y < -1.2) in the transverse-momentum (pT) range from 1-7 GeV/c and at midrapidity │y│< 0.35 in the pT range below 7 GeV/c. The φ meson invariant yields and nuclear-modification factors as a function of pT, rapidity, and centrality are reported. An enhancement of φ meson production is observed in the Au-going direction, while suppression is seen in the d-going direction, and no modification is observed at midrapidity relative to the yield in p+p collisions scaled by the number of binary collisions. Similar behavior was previously observed for inclusive charged hadrons and open heavy flavor, indicating similar cold-nuclear-matter effects.


Systematic Study Of Azimuthal Anisotropy In Cu + Cu And Au + Au Collisions At √Snn =62.4 And 200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Klaus Dehmelt, Marcus Hohlmann, S. Rembeczki, PHENIX Collaboration 2015 University of Colorado, Boulder

Systematic Study Of Azimuthal Anisotropy In Cu + Cu And Au + Au Collisions At √Snn =62.4 And 200 Gev, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Klaus Dehmelt, Marcus Hohlmann, S. Rembeczki, Phenix Collaboration

Aerospace, Physics, and Space Science Faculty Publications

We have studied the dependence of azimuthal anisotropy v₂ for inclusive and identified charged hadrons in Au+Au and Cu+Cu collisions on collision energy, species, and centrality. The values of v₂ as a function of transverse momentum pT and centrality in Au+Au collisions at sNN=200 and 62.4 GeV are the same within uncertainties. However, in Cu+Cu collisions we observe a decrease in v₂ values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au+Au and Cu+Cu collisions we find that v₂ depends both on eccentricity and the …


Digital Commons powered by bepress