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Articles 4021 - 4050 of 8858

Full-Text Articles in Astrophysics and Astronomy

Observations Of An Energetically Isolated Quiet Sun Transient: Evidence Of Quasi-Steady Coronal Heating, Norton Brice Orange, David L. Chesney, Hakeem M. Oluseyi Sep 2015

Observations Of An Energetically Isolated Quiet Sun Transient: Evidence Of Quasi-Steady Coronal Heating, Norton Brice Orange, David L. Chesney, Hakeem M. Oluseyi

Aerospace, Physics, and Space Science Faculty Publications

Increasing evidence for coronal heating contributions from cooler solar atmospheric layers, notably quiet Sun (QS) conditions, challenges standard solar atmospheric descriptions of bright transition region (TR) emission. As such, questions about the role of dynamic QS transients in contributing to the total coronal energy budget are raised. Using observations from the Atmospheric Imaging Assembly and Heliosemic Magnetic Imager on board the Solar Dynamics Observatory, and numerical model extrapolations of coronal magnetic fields, we investigate a dynamic QS transient that is energetically isolated to the TR and extrudes from a common footpoint shared with two heated loop arcades. A non-causal relationship …

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Nanograv Constraints On Gravitational Wave Bursts With Memory, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, J. M. Cordes, N. J. Cornish, Fredrick A. Jenet, Jing Luo Sep 2015

Nanograv Constraints On Gravitational Wave Bursts With Memory, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, J. M. Cordes, N. J. Cornish, Fredrick A. Jenet, Jing Luo

Physics & Astronomy Faculty Publications

Among efforts to detect gravitational radiation, pulsar timing arrays are uniquely poised to detect \"memory\" signatures, permanent perturbations in spacetime from highly energetic astrophysical events such as mergers of supermassive black hole binaries. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) observes dozens of the most stable millisecond pulsars using the Arecibo and Green Bank radio telescopes in an effort to study, among other things, gravitational wave memory. We herein present the results of a search for gravitational wave bursts with memory (BWMs) using the first five years of NANOGrav observations. We develop original methods for dramatically speeding up …

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The Nature And Frequency Of Outflows From Stars In The Central Orion Nebula Cluster, C. R. O'Dell, Gary J. Ferland, W. J. Henney, M. Peimbert, Ma. T. García-Díaz, Robert H. Rubin Sep 2015

The Nature And Frequency Of Outflows From Stars In The Central Orion Nebula Cluster, C. R. O'Dell, Gary J. Ferland, W. J. Henney, M. Peimbert, Ma. T. García-Díaz, Robert H. Rubin

Physics and Astronomy Faculty Publications

Recent Hubble Space Telescope images have allowed the determination with unprecedented accuracy of motions and changes of shocks within the inner Orion Nebula. These originate from collimated outflows from very young stars, some within the ionized portion of the nebula and others within the host molecular cloud. We have doubled the number of Herbig–Haro objects known within the inner Orion Nebula. We find that the best-known Herbig–Haro shocks originate from relatively few stars, with the optically visible X-ray source COUP 666 driving many of them. While some isolated shocks are driven by single collimated outflows, many groups of shocks are …

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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 = …

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Eletron-Helium Laser-Assisted Free-Free Scattering For Incident Energies From 30 - 200 Ev: Effects Of Polarization Direction, B. A. Deharak, Benjamin Nosarzewski, Mahsa Siavashpouri, Nicholas L. S. Martin Sep 2015

Eletron-Helium Laser-Assisted Free-Free Scattering For Incident Energies From 30 - 200 Ev: Effects Of Polarization Direction, B. A. Deharak, Benjamin Nosarzewski, Mahsa Siavashpouri, Nicholas L. S. Martin

Physics and Astronomy Faculty Publications

We report on experiments that examine electron-helium scattering in the presence of an Nd:YAG laser field of 1.17 eV photons. At each incidentelectron energy (30, 60, and 200 eV), the laser polarization direction is varied within a plane perpendicular to the Watson approximation calculations.

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The Sluggs Survey: Inferring The Formation Epochs Of Metal-Poor And Metal-Rich Globular Clusters, Duncan Forbes, Nicola Pastorello, Aaron Romanowsky, Christopher Usher, Jean Brodie, Jay Strader Sep 2015

The Sluggs Survey: Inferring The Formation Epochs Of Metal-Poor And Metal-Rich Globular Clusters, Duncan Forbes, Nicola Pastorello, Aaron Romanowsky, Christopher Usher, Jean Brodie, Jay Strader

Faculty Publications

We present a novel, observationally-based framework for the formation epochs and sites of globular clusters (GCs) in a cosmological context. Measuring directly the mean ages of the metal-poor and metal-rich GC subpopulations in our own Galaxy, and in other galaxies, is observationally challenging. Here we apply an alternative approach utilizing the property that the galaxy mass–metallicity relation is a strong function of redshift (or look-back age) but is relatively insensitive to galaxy mass for massive galaxies. Assuming that GCs follow galaxy mass–metallicity relations that evolve with redshift, one can estimate the mean formation epochs of the two GC subpopulations by …

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Vegas: A Vst Early-Type Galaxy Survey: I. Presentation, Wide-Field Surface Photometry, And Substructures In Ngc 4472, Massimo Capaccioli, Marilena Spavone, Aniello Grado, Enrichetta Iodice, Luca Limatola, Nicola Napolitano, Michele Cantiello, Maurizio Paolillo, Aaron Romanowsky, Duncan Forbes, Thomas Puzia, Gabriella Raimondo, Pietro Schipani Sep 2015

Vegas: A Vst Early-Type Galaxy Survey: I. Presentation, Wide-Field Surface Photometry, And Substructures In Ngc 4472, Massimo Capaccioli, Marilena Spavone, Aniello Grado, Enrichetta Iodice, Luca Limatola, Nicola Napolitano, Michele Cantiello, Maurizio Paolillo, Aaron Romanowsky, Duncan Forbes, Thomas Puzia, Gabriella Raimondo, Pietro Schipani

Faculty Publications

Context. We present the VST Early-type GAlaxy Survey (VEGAS), which is designed to obtain deep multiband photometry in g,r,i, of about one hundred nearby galaxies down to 27.3, 26.8, and 26 mag/arcsec2 respectively, using the ESO facility VST/OmegaCAM.Aims. The goals of the survey are 1) to map the light distribution up to ten effective radii, re; 2) to trace color gradients and surface brightness fluctuation gradients out to a few re for stellar population characterization; and 3) to obtain a full census of the satellite systems (globular clusters and dwarf galaxies) out to 20% of the galaxy virial radius. The …

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Vimos Mosaic Integral-Field Spectroscopy Of The Bulge And Disc Of The Early-Type Galaxy Ngc 4697, C. Spiniello, N. Napolitano, L. Coccato, V. Pota, Aaron Romanowsky, C. Tortora, G. Covone, M. Capaccioli Sep 2015

Vimos Mosaic Integral-Field Spectroscopy Of The Bulge And Disc Of The Early-Type Galaxy Ngc 4697, C. Spiniello, N. Napolitano, L. Coccato, V. Pota, Aaron Romanowsky, C. Tortora, G. Covone, M. Capaccioli

Faculty Publications

No abstract provided.

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Inelastic Neutron Scattering Cross Sections For 76Ge Relevant To Background In Neutrinoless Double-Β Decay Experiments, Benjamin P. Crider, Erin Elizabeth Peters, J. M. Allmond, Marcus T. Mcellistrem, Francisco M. Prados-Estévez, T. J. Ross, J. R. Vanhoy, Steven W. Yates Sep 2015

Inelastic Neutron Scattering Cross Sections For 76Ge Relevant To Background In Neutrinoless Double-Β Decay Experiments, Benjamin P. Crider, Erin Elizabeth Peters, J. M. Allmond, Marcus T. Mcellistrem, Francisco M. Prados-Estévez, T. J. Ross, J. R. Vanhoy, Steven W. Yates

Physics and Astronomy Faculty Publications

The experimental signature in searches for the neutrinoless double-β decay of 76Ge is a peak near 2039 keV in the spectrum. Given the low probability of the process, it is important that the background in this region be well understood. Inelastic scattering reactions with neutrons from muon-induced interactions and (α,n) reactions in the surrounding materials or in the detector can provide contributions to the background. We have measured the production cross sections for γ rays from the 76Ge(n,n'γ ) reaction in the 2039-keV region at incident neutron energies up to …

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Kelt-8b: A Highly Inflated Transiting Hot Jupiter And A New Technique For Extracting High-Precision Radial Velocities From Noisy Spectra, B. J. Fulton, K. A. Collins, B. S. Gaudi, K. G. Stassun, J. Pepper, T. G. Beatty, R. J. Siverd, K. Penev, A. W. Howard, C. Baranec, G. Corfini, J. D. Eastman, J. Gregorio, N. M. Law, M. B. Lund, T. E. Oberst, M. T. Penny, R. Riddle, J. E. Rodriguez, D. J. Stevens, R. Zambelli, C. Ziegler, A. Bieryla, G. D'Ago, D. L. Depoy, Eric L.N. Jensen, J. F. Kielkopf, D. W. Latham, M. Manner, J. Marshall, K. K. Mcleod, P. A. Reed Sep 2015

Kelt-8b: A Highly Inflated Transiting Hot Jupiter And A New Technique For Extracting High-Precision Radial Velocities From Noisy Spectra, B. J. Fulton, K. A. Collins, B. S. Gaudi, K. G. Stassun, J. Pepper, T. G. Beatty, R. J. Siverd, K. Penev, A. W. Howard, C. Baranec, G. Corfini, J. D. Eastman, J. Gregorio, N. M. Law, M. B. Lund, T. E. Oberst, M. T. Penny, R. Riddle, J. E. Rodriguez, D. J. Stevens, R. Zambelli, C. Ziegler, A. Bieryla, G. D'Ago, D. L. Depoy, Eric L.N. Jensen, J. F. Kielkopf, D. W. Latham, M. Manner, J. Marshall, K. K. Mcleod, P. A. Reed

Physics & Astronomy Faculty Works

We announce the discovery of a highly inflated transiting hot Jupiter by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with {T}{eff}={5754}-55+54 K, {log} g={4.078}-0.054+0.049, [{Fe}/{{H}}]=0.272+/- 0.038, an inferred mass {M}*={1.211}-0.066+0.078 {M}☉ , and radius {R}*={1.67}-0.12+0.14 {R}☉ . The planetary companion has a mass {M}{{P}}={0.867}-0.061+0.065 MJ, radius {R}{{P}}={1.86}-0.16+0.18 RJ, surface gravity {log} {g} …

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The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace Sep 2015

The Strange Evolution Of The Large Magellanic Cloud Cepheid Ogle-Lmc-Cep1812, Hilding R. Neilson, Robert G. Izzard, Nobert Langer, Richard Ignace

ETSU Faculty Works

Classical Cepheids are key probes of both stellar astrophysics and cosmology as standard candles and pulsating variable stars. It is important to understand Cepheids in unprecedented detail in preparation for upcoming Gaia, James Webb Space Telescope (JWST) and extremely-large telescope observations. Cepheid eclipsing binary stars are ideal tools for achieving this goal, however there are currently only three known systems. One of those systems, OGLE-LMC-CEP1812, raises new questions about the evolution of classical Cepheids because of an apparent age discrepancy between the Cepheid and its red giant companion. We show that the Cepheid component is actually the product of a …

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Low Intensity Gamma-Ray Spectroscopy Of The Lake Labyrinth Meteorite, Tristan C. Paul Sep 2015

Low Intensity Gamma-Ray Spectroscopy Of The Lake Labyrinth Meteorite, Tristan C. Paul

Physics

A 23.7g fragment of the Lake Labyrinth Meteorite (fell in 1924, collected in 1934 at Lake Labyrinth in South Australia, Australia) was re-investigated for evidence of the presence of 98Tc using a two dimensional low-intensity gamma-ray spectrometer. A new calibration technique using 26Al sources found the gamma-rays previously thought to be due to 98Tc are more likely from 166Ho. The presence of 166Ho is most likely due to activation of the stable 165Ho in the meteorite from terrestrial background sources where it was stored.

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Reionization After Planck : The Derived Growth Of The Cosmic Ionizing Emissivity Now Matches The Growth Of The Galaxy Uv Luminosity Density., R. J. Bouwens, G. D. Illingworth, P. A. Oesch, J. Caruana, Benne W. Holwerda, R. Smit, S. M. Wilkins Sep 2015

Reionization After Planck : The Derived Growth Of The Cosmic Ionizing Emissivity Now Matches The Growth Of The Galaxy Uv Luminosity Density., R. J. Bouwens, G. D. Illingworth, P. A. Oesch, J. Caruana, Benne W. Holwerda, R. Smit, S. M. Wilkins

Faculty and Staff Scholarship

Thomson optical depth τ measurements from Planck provide new insights into the reionization of the universe. In pursuit of model-independent constraints on the properties of the ionizing sources, we determine the empirical evolution of the cosmic ionizing emissivity. We use a simple two-parameter model to map out the evolution in the emissivity at z  6 from the new Planck optical depth τ measurements, from the constraints provided by quasar absorption spectra and from the prevalence of Lyα emission in z ∼ 7–8 galaxies. We find the redshift evolution in the emissivity Nion z ˙ ( ) required by the …

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Galaxy And Mass Assembly (Gama) : End Of Survey Report And Data Release 2., J. Liske, I. K. Baldry, S. P. Driver, R. J. Tuffs, M. Alpaslan, E. Andrae, S. Brough, M. E. Cluver, M. W. Grootes, M. L. P. Gunawardhana, L. S. Kelvin, J. Loveday, A. S. G. Robotham, E. N. Taylor, S. P. Bamford, J. Bland-Hawthorn, M. J. I. Brown, M. J. Drinkwater, A. M. Hopkins, M. Meyer, P. Norberg, J. A. Peacock, N. K. Agius, S. K. Andrews, A. E. Bauer, J. H. Y. Ching, M. Colless, C. J. Conselice, S. M. Croom, L. J. M. Davies, R. De Propris, L. Dunne, E. M. Eardley, S. Ellis, C. Foster, C. S. Frenk, B. Haußler, Benne W. Holwerda, C. Howlett, H. Ibarra, M. J. Jarvis, D. H. Jones, P. R. Kafle, C. G. Lacey, R. Lange, M. Lara-Lopez, Angel R. Lopez-Sanchez, S. J. Maddox, B. F. Madore, T. Mcnaught-Roberts, A. J. Moffett, R. C. Nichol, M. S. Owers, D. Palamara, S. J. Penny, S. Phillipps, K. A. Pimbblet, C. C. Popescu, M. Prescott, R. Proctor, E. M. Sadler, A. E. Sansom, M. Seibert, R. Sharp, W. Sutherland, J. A. Vazquez-Mata, E. Van Kampen, S. M. Wilkins, R. Williams, A. H. Wright Sep 2015

Galaxy And Mass Assembly (Gama) : End Of Survey Report And Data Release 2., J. Liske, I. K. Baldry, S. P. Driver, R. J. Tuffs, M. Alpaslan, E. Andrae, S. Brough, M. E. Cluver, M. W. Grootes, M. L. P. Gunawardhana, L. S. Kelvin, J. Loveday, A. S. G. Robotham, E. N. Taylor, S. P. Bamford, J. Bland-Hawthorn, M. J. I. Brown, M. J. Drinkwater, A. M. Hopkins, M. Meyer, P. Norberg, J. A. Peacock, N. K. Agius, S. K. Andrews, A. E. Bauer, J. H. Y. Ching, M. Colless, C. J. Conselice, S. M. Croom, L. J. M. Davies, R. De Propris, L. Dunne, E. M. Eardley, S. Ellis, C. Foster, C. S. Frenk, B. Haußler, Benne W. Holwerda, C. Howlett, H. Ibarra, M. J. Jarvis, D. H. Jones, P. R. Kafle, C. G. Lacey, R. Lange, M. Lara-Lopez, Angel R. Lopez-Sanchez, S. J. Maddox, B. F. Madore, T. Mcnaught-Roberts, A. J. Moffett, R. C. Nichol, M. S. Owers, D. Palamara, S. J. Penny, S. Phillipps, K. A. Pimbblet, C. C. Popescu, M. Prescott, R. Proctor, E. M. Sadler, A. E. Sansom, M. Seibert, R. Sharp, W. Sutherland, J. A. Vazquez-Mata, E. Van Kampen, S. M. Wilkins, R. Williams, A. H. Wright

Faculty and Staff Scholarship

The Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. Covering an area of ∼286 deg2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm–1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Sérsic fits, stellar masses, Hα-derived star formation rates, environment information, and group properties for all galaxies with r < 19.0 mag in two of our survey regions, and for all galaxies with r < 19.4 mag in a third region (72 225 objects in total). The data base serving these data is available at http://www.gama-survey.org/.

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Dna Cyclization And Looping In The Wormlike Limit: Normal Modes And The Validity Of The Harmonic Approximation, Stefan M. Giovan, Andreas Hanke, Stephen D. Levene Sep 2015

Dna Cyclization And Looping In The Wormlike Limit: Normal Modes And The Validity Of The Harmonic Approximation, Stefan M. Giovan, Andreas Hanke, Stephen D. Levene

Physics & Astronomy Faculty Publications

For much of the last three decades, Monte Carlo-simulation methods have been the standard approach for accurately calculating the cyclization probability, J, or J factor, for DNA models having sequence-dependent bends or inhomogeneous bending flexibility. Within the last 10 years approaches based on harmonic analysis of semi-flexible polymer models have been introduced, which offer much greater computational efficiency than Monte Carlo techniques. These methods consider the ensemble of molecular conformations in terms of harmonic fluctuations about a well-defined elastic-energy minimum. However, the harmonic approximation is only applicable for small systems, because the accessible conformation space of larger systems is increasingly …

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The Sluggs Survey: Globular Cluster Kinematics In A ‘Double Sigma’ Galaxy – Ngc 4473, Adebusola Alabi, Caroline Foster, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Jean Brodie, Lee Spitler, Jay Strader, Christopher Usher Sep 2015

The Sluggs Survey: Globular Cluster Kinematics In A ‘Double Sigma’ Galaxy – Ngc 4473, Adebusola Alabi, Caroline Foster, Duncan Forbes, Aaron Romanowsky, Nicola Pastorello, Jean Brodie, Lee Spitler, Jay Strader, Christopher Usher

Faculty Publications

NGC 4473 is a so-called double sigma (2σ) galaxy, i.e. a galaxy with rare, double peaks in its 2D stellar velocity dispersion. Here, we present the globular cluster (GC) kinematics in NGC 4473 out to ∼10Re (effective radii) using data from combined Hubble Space Telescope/Advanced Camera for Surveys and Subaru/Suprime-Cam imaging and Keck/Deep Imaging Multi-Object Spectrograph. We find that the 2σ nature of NGC 4473 persists up to 3Re, though it becomes misaligned to the photometric major axis. We also observe a significant offset between the stellar and GC rotation amplitudes. This offset can be understood as a co-addition of …

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Precision Measurement Of The Longitudinal Double-Spin Asymmetry For Inclusive Jet Production In Polarized Proton Collisions At √S=200 Gev, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, Grant D. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer Aug 2015

Precision Measurement Of The Longitudinal Double-Spin Asymmetry For Inclusive Jet Production In Polarized Proton Collisions At √S=200 Gev, James K. Adkins, Renee H. Fatemi, Suvarna Ramachandran, Grant D. Webb, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, C. D. Anson, A. Aparin, D. Arkhipkin, E. C. Aschenauer

Physics and Astronomy Faculty Publications

We report a new measurement of the midrapidity inclusive jet longitudinal double-spin asymmetry, ALL, in polarized pp collisions at center-of-mass energy √s=200  GeV. The STAR data place stringent constraints on polarized parton distribution functions extracted at next-to-leading order from global analyses of inclusive deep-inelastic scattering (DIS), semi-inclusive DIS, and RHIC pp data. The measured asymmetries provide evidence at the 3σ level for positive gluon polarization in the Bjorken-x region x>0.05.

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Stability Bounds On Compact Astrophysical Objects From Information-Entropic Measure, Marcelo Gleiser, Nan Jiang Aug 2015

Stability Bounds On Compact Astrophysical Objects From Information-Entropic Measure, Marcelo Gleiser, Nan Jiang

Dartmouth Scholarship

We obtain bounds on the stability of various self-gravitating astrophysical objects using a new measure of shape complexity known as configurational entropy. We apply the method to Newtonian polytropes, neutron stars with an Oppenheimer-Volkoff equation of state, and to self-gravitating configurations of complex scalar field (boson stars) with different self couplings, showing that the critical stability region of these stellar configurations obtained from traditional perturbation methods correlates well with critical points of the configurational entropy with accuracy of a few percent or better.

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Xo-2b: A Hot Jupiter With A Variable Host Star That Potentially Affects Its Measured Transit Depth, Robert T. Zellem, Caitlin A. Griffith, Kyle A. Pearson, Jake D. Turner, Gregory W. Henry, Michael H. Williamson, ‪Morgan Ryleigh Fitzpatrick, Johanna K. Teske, Lauren I. Biddle Aug 2015

Xo-2b: A Hot Jupiter With A Variable Host Star That Potentially Affects Its Measured Transit Depth, Robert T. Zellem, Caitlin A. Griffith, Kyle A. Pearson, Jake D. Turner, Gregory W. Henry, Michael H. Williamson, ‪Morgan Ryleigh Fitzpatrick, Johanna K. Teske, Lauren I. Biddle

Information Systems and Engineering Management Research Publications

The transiting hot Jupiter XO-2b is an ideal target for multi-object photometry and spectroscopy as it has a relatively bright (V-mag = 11.25) K0V host star (XO-2N) and a large planet-to-star contrast ratio (Rp/Rs ≈ 0.015). It also has a nearby (31farcs21) binary stellar companion (XO-2S) of nearly the same brightness (V-mag = 11.20) and spectral type (G9V), allowing for the characterization and removal of shared systematic errors (e.g., airmass brightness variations). We have therefore conducted a multiyear (2012–2015) study of XO-2b with the University of Arizona's 61'' (1.55 m) Kuiper Telescope and Mont4k CCD in the Bessel U and …

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Ground-Based Transit Observations Of The Hat-P-18, Hat-P-19, Hat-P-27/Wasp40 And Wasp-21 Systems, M. Seeliger, M. Kitze, R. Errmann, S. Richter, J. M. Ohlert, W. P. Chen, J. K. Guo, E. Göğüş, T. Güver, B. Aydın, S. Mottola, S. Hellmich, M. Fernandez, F. J. Aceituno, D. Dimitrov, D. Kjurkchieva, Eric L.N. Jensen, David H. Cohen, E. Kundra, T. Pribulla, M. Vaňko, J. Budaj, M. Mallonn, Z.-Y. Wu, X. Zhou, St. Raetz, C. Adam, T. O. B. Schmidt, A. Ide, M. Mugrauer, L. Marschall, M. Hackstein, R. Chini, M. Haas, T. Ak, E. Güzel, A. Özdönmez, C. Ginski, C. Marka, J. G. Schmidt, B. Dincel, K. Werner, A. Dathe, J. Greif, V. Wolf, S. Buder, A. Pannicke, D. Puchalski, R. Neuhäuser Aug 2015

Ground-Based Transit Observations Of The Hat-P-18, Hat-P-19, Hat-P-27/Wasp40 And Wasp-21 Systems, M. Seeliger, M. Kitze, R. Errmann, S. Richter, J. M. Ohlert, W. P. Chen, J. K. Guo, E. Göğüş, T. Güver, B. Aydın, S. Mottola, S. Hellmich, M. Fernandez, F. J. Aceituno, D. Dimitrov, D. Kjurkchieva, Eric L.N. Jensen, David H. Cohen, E. Kundra, T. Pribulla, M. Vaňko, J. Budaj, M. Mallonn, Z.-Y. Wu, X. Zhou, St. Raetz, C. Adam, T. O. B. Schmidt, A. Ide, M. Mugrauer, L. Marschall, M. Hackstein, R. Chini, M. Haas, T. Ak, E. Güzel, A. Özdönmez, C. Ginski, C. Marka, J. G. Schmidt, B. Dincel, K. Werner, A. Dathe, J. Greif, V. Wolf, S. Buder, A. Pannicke, D. Puchalski, R. Neuhäuser

Physics & Astronomy Faculty Works

As part of our ongoing effort to investigate transit timing variations (TTVs) of known exoplanets, we monitored transits of the four exoplanets HAT-P-18b, HAT-P-19b, HAT-P-27b/WASP-40b and WASP-21b. All of them are suspected to show TTVs due to the known properties of their host systems based on the respective discovery papers. During the past three years 46 transit observations were carried out, mostly using telescopes of the Young Exoplanet Transit Initiative. The analyses are used to refine the systems’ orbital parameters. In all cases we found no hints for significant TTVs, or changes in the system parameters inclination, fractional stellar radius …

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Detecting The Companions And Ellipsoidal Variations Of Rs Cvn Primaries. Ii. O Draconis, A Candidate For Recent Low-Mass Companion Ingestion, Rachael M. Roettenbacher, John D. Monnier, Francis C. Fekel, Gregory W. Henry, Heidi Korhonen, David W. Latham, Matthew W. Muterspaugh, Michael H. Williamson, Fabien Baron, Theo A. Ten Brummelaar, Xiao Che, Robert O. Harmon, Gail H. Schaefer, Nicholas J. Scott, Judit Sturmann, Laszlo Sturmann, Nils H. Turner Aug 2015

Detecting The Companions And Ellipsoidal Variations Of Rs Cvn Primaries. Ii. O Draconis, A Candidate For Recent Low-Mass Companion Ingestion, Rachael M. Roettenbacher, John D. Monnier, Francis C. Fekel, Gregory W. Henry, Heidi Korhonen, David W. Latham, Matthew W. Muterspaugh, Michael H. Williamson, Fabien Baron, Theo A. Ten Brummelaar, Xiao Che, Robert O. Harmon, Gail H. Schaefer, Nicholas J. Scott, Judit Sturmann, Laszlo Sturmann, Nils H. Turner

Information Systems and Engineering Management Research Publications

To measure the stellar and orbital properties of the metal-poor RS CVn binary o Draconis (o Dra), we directly detect the companion using interferometric observations obtained with the Michigan InfraRed Combiner at Georgia State University's Center for High Angular Resolution Astronomy (CHARA) Array. The H-band flux ratio between the primary and secondary stars is the highest confirmed flux ratio (370 ± 40) observed with long-baseline optical interferometry. These detections are combined with radial velocity data of both the primary and secondary stars, including new data obtained with the Tillinghast Reflector Echelle Spectrograph on the Tillinghast Reflector at the Fred Lawrence …

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Chang-Es V: Nuclear Outflow In A Virgo Cluster Spiral After A Tidal Disruption Event, Judith A. Irwin, Richard N. Henriksen, Marita Krause, Daniel Q. Wang, Theresa Wiegert, Eric J. Murphy, George Heald, Eric S. Perlman Aug 2015

Chang-Es V: Nuclear Outflow In A Virgo Cluster Spiral After A Tidal Disruption Event, Judith A. Irwin, Richard N. Henriksen, Marita Krause, Daniel Q. Wang, Theresa Wiegert, Eric J. Murphy, George Heald, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We have observed the Virgo Cluster spiral galaxy, NGC 4845, at 1.6 and 6 GHz using the Karl G. Jansky Very Large Array, as part of the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES). The source consists of a bright unresolved core with a surrounding weak central disk (1.8 kpc diameter). The core is variable over the 6 month timescale of the CHANG-ES data and has increased by a factor of ≈6 since 1995. The wide bandwidths of CHANG-ES have allowed us to determine the spectral evolution of this core, which peaks between 1.6 and 6 GHz (it is …

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Magnetohydrodynamic Modeling Of Three Van Allen Probes Storms In 2012 And 2013, J. Paral, M. K. Hudson, B. T. Kress, M. J. Wiltberger Aug 2015

Magnetohydrodynamic Modeling Of Three Van Allen Probes Storms In 2012 And 2013, J. Paral, M. K. Hudson, B. T. Kress, M. J. Wiltberger

Dartmouth Scholarship

Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L=4.5, well within the computed magnetopause location. We compare ULF wave …

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A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping Aug 2015

A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Ori Aa: I. Overview Of The X-Ray Spectrum., Michael Corcoran, Joy Nichols, H. Pablo, Tomer Shenar, Andy Pollock, W. Waldron, A. Moffat, N. Richardson, C. Russell, K. Hamaguchi, D. Huenemoerder, L. Oskinova, W.-R. Hamann, Y. Nazé, Richard Ignace, Nancy Evans, Jamie Lomax, J. Hoffman, K. Gayley, S. Owocki, M. Leutenegger, T. Gull, K. Hole, J. Lauer, R. Iping

ETSU Faculty Works

We present an overview of four deep phase-constrained Chandra HETGS X-ray observations of δ Ori A. Delta Ori A is actually a triple system that includes the nearest massive eclipsing spectroscopic binary, δ Ori Aa, the only such object that can be observed with little phase-smearing with the Chandra gratings. Since the fainter star, δ Ori Aa2, has a much lower X-ray luminosity than the brighter primary (δ Ori Aa1), δ Ori Aa provides a unique system with which to test the spatial distribution of the X-ray emitting gas around δ Ori Aa1 via occultation by the photosphere of, and …

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A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss Aug 2015

A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa. Iii. Analysis Of Optical Photometric (Most) And Spectroscopic (Ground Based) Variations., Herbert Pablo, Noel Richardson, Anthony Moffat, Michael Corcoran, Tomer Shenar, Omar Benvenuto, Jim Fuller, Yaël Nazé, Jennifer Hoffman, Anatoly Miroshnichenko, Jesús Apellániz, Nancy Evans, Thomas Eversberg, Ken Gayley, Ted Gull, Kenji Hamaguchi, Wolf-Rainer Hamann, Huib Henrichs, Tabetha Hole, Richard Ignace, Rosina Iping, Jennifer Lauer, Maurice Leutenegger, Jamie Lomax, Joy Nichols, Lida Oskinova, Stan Owocki, Andy Pollock, Christopher Russell, Wayne Waldron, Christian Buil, Thierry Garrel, Keith Graham, Bernard Heathcote, Thierry Lemoult, Dong Li, Benjamin Mauclaire, Mike Potter, Jose Ribeiro, Jaymie Matthews, Chris Cameron, David Guenther, Rainer Kuschnig, Jason Rowe, Slavek Rucinski, Dimitar Sasselov, Werner Weiss

ETSU Faculty Works

We report on both high-precision photometry from the Microvariability and Oscillations of Stars (MOST) space telescope and ground-based spectroscopy of the triple system δ Ori A, consisting of a binary O9.5II+early-B(Aa1 and Aa2) with P=5.7 days, and a more distant tertiary(O9 IV P 400 years). This data was collected in concert with X-ray spectroscopy from the Chandra X-ray Observatory. Thanks to continuous coverage for three weeks, the MOST light curve reveals clear eclipses between Aa1 and Aa2 for the first time in non-phased data. From the spectroscopy, we have a well-constrained radial velocity (RV)curve of Aa1. While we are unable …

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A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa: Ii. X-Ray Variability., Joy Nichols, D. Huenemoerder, Michael Corcoran, W. Waldron, Y. Nazé, Andy Pollock, A. Moffat, J. Lauer, Tomer Shenar, C. Russell, N. Richardson, H. Pablo, N. Evans, K. Hamaguchi, T. Gull, W.-R. Hamann, L. Oskinova, Richard Ignace, Jennifer Hoffman, K. Hole, Jamie Lomax Aug 2015

A Coordinated X-Ray And Optical Campaign Of The Nearest Massive Eclipsing Binary, Δ Orionis Aa: Ii. X-Ray Variability., Joy Nichols, D. Huenemoerder, Michael Corcoran, W. Waldron, Y. Nazé, Andy Pollock, A. Moffat, J. Lauer, Tomer Shenar, C. Russell, N. Richardson, H. Pablo, N. Evans, K. Hamaguchi, T. Gull, W.-R. Hamann, L. Oskinova, Richard Ignace, Jennifer Hoffman, K. Hole, Jamie Lomax

ETSU Faculty Works

We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the δ Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of ≈ 479 ks and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range of 5–25 Å is confirmed, with a maximum amplitude of about ±15% within a single ≈ 125 ks observation. Periods of 4.76 and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in the flux level throughout the …

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Phase-Coherent Mapping Of Gravitational-Wave Backgrounds Using Ground-Based Laser Interferometers, Joseph D. Romano, Stephen R. Taylor, Neil Cornish, Jonathan Gair, Chiara M. F. Mingarelli, Rutger Van Haasteren Aug 2015

Phase-Coherent Mapping Of Gravitational-Wave Backgrounds Using Ground-Based Laser Interferometers, Joseph D. Romano, Stephen R. Taylor, Neil Cornish, Jonathan Gair, Chiara M. F. Mingarelli, Rutger Van Haasteren

Physics & Astronomy Faculty Publications

We extend the formalisms developed in Gair et al. [1] and Cornish and van Haasteren [2] to create maps of gravitational-wave backgrounds using a network of ground-based laser interferometers. We show that in contrast to pulsar timing arrays, which are insensitive to the curl modes of the background, a network of ground-based interferometers is sensitive to both the gradient and curl components. The spatial separation of a network of interferometers, or of a single interferometer at different times during its rotational and orbital motion around the Sun, allows for recovery of both components. We derive expressions for the response functions …

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Sr2Ir1−XRhXO4(X<0.5): An Inhomogeneous JEff=1/2 Hubbard System, Shalinee Chikara, Daniel Haskel, Jae-Hoon Sim, Heung-Sik Kim, Cheng-Chien Chen, G. Fabbris, L. S. I. Veiga, N. M. Souza-Neto, Jsaminka Terzic, Kamal H. Butrouna, Gang Cao, Myung Joon Han, Michael Van Veenendaal Aug 2015

Sr2Ir1−XRhXO4(X<0.5): An Inhomogeneous JEff=1/2 Hubbard System, Shalinee Chikara, Daniel Haskel, Jae-Hoon Sim, Heung-Sik Kim, Cheng-Chien Chen, G. Fabbris, L. S. I. Veiga, N. M. Souza-Neto, Jsaminka Terzic, Kamal H. Butrouna, Gang Cao, Myung Joon Han, Michael Van Veenendaal

Physics and Astronomy Faculty Publications

In a combined experimental and theoretical study, we investigate the properties of Sr2Ir1−xRhxO4. From the branching ratios of the L-edge isotropic x-ray absorption spectra, we determine that the spin-orbit coupling is remarkably independent of x for both iridium and rhodium sites. DFT+U calculations show that the doping is close to isoelectronic and introduces impurity bands of predominantly rhodium character close to the lower Hubbard band. Overlap of these two bands leads to metallic behavior. Since the low-energy states for xjeff=1/2 character, we suggest that the electronic …

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Anomalous High-Energy Waterfall-Like Electronic Structure In 5 D Transition Metal Oxide Sr2Iro4 With A Strong Spin-Orbit Coupling, Yan Liu, Li Yu, Xiaowen Jia, Jianzhou Zhao, Hongming Weng, Yingying Peng, Chaoyu Chen, Zhuojin Xie, Daixiang Mou, Junfeng He, Xu Liu, Ya Feng, Hemian Yi, Lin Zhao, Guodong Liu, Shaolong He, Xiaoli Dong, Jun Zhang, Zuyan Xu, Chuangtian Chen, Gang Cao, Xi Dai, Zhong Fang, X. J. Zhou Aug 2015

Anomalous High-Energy Waterfall-Like Electronic Structure In 5 D Transition Metal Oxide Sr2Iro4 With A Strong Spin-Orbit Coupling, Yan Liu, Li Yu, Xiaowen Jia, Jianzhou Zhao, Hongming Weng, Yingying Peng, Chaoyu Chen, Zhuojin Xie, Daixiang Mou, Junfeng He, Xu Liu, Ya Feng, Hemian Yi, Lin Zhao, Guodong Liu, Shaolong He, Xiaoli Dong, Jun Zhang, Zuyan Xu, Chuangtian Chen, Gang Cao, Xi Dai, Zhong Fang, X. J. Zhou

Physics and Astronomy Faculty Publications

The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. …

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Stellar Populations And The Star Formation Histories Of Lsb Galaxies. V. Wfc3 Color-Magnitude Diagrams, Stacy S. Mcgaugh Aug 2015

Stellar Populations And The Star Formation Histories Of Lsb Galaxies. V. Wfc3 Color-Magnitude Diagrams, Stacy S. Mcgaugh

Faculty Scholarship

We present WFC3 observations of three low surface brightness (LSB) galaxies from the Schombert et al. LSB catalog that are within 11 Mpc of the Milky Way. Deep imaging at F336W, F555W, and F814W allow the construction of the V - I color-magnitude diagrams (CMD) to MI = -2. Overall 1869, 465, and 501 stellar sources are identified in the three LSB galaxies F415-3, F608-1, and F750-V1, respectively. The spatial distribution of young blue stars matches the H maps from ground-based imaging, indicating that star formation in LSB galaxies follows the same style as in other irregular galaxies. Several star …

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