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Articles 5551 - 5580 of 8864

Full-Text Articles in Astrophysics and Astronomy

The Sn 393-Snr Rx J1713.7-3946 (G347.3-0.5) Connection, Robert A. Fesen, Richard Kremer, Daniel Patnaude, Dan Milisavljevic Dec 2011

The Sn 393-Snr Rx J1713.7-3946 (G347.3-0.5) Connection, Robert A. Fesen, Richard Kremer, Daniel Patnaude, Dan Milisavljevic

Dartmouth Scholarship

Although the connection of the Chinese "guest" star of 393 AD with the Galactic supernova remnant RX J1713.7-3946 (G347.3-0.5) made by Wang et al. in 1997 is consistent with the remnant's relatively young properties and the guest star's projected position within the "tail" of the constellation Scorpius, there are difficulties with such an association. The brief Chinese texts concerning the 393 AD guest star make no comment about its apparent brightness, stating only that it disappeared after eight months. However, at the remnant's current estimated 1-1.3 kpc distance and A V 3, its supernova (SN) should have been a visually …

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Veritas Observations Of Gamma-Ray Bursts Detected By Swift, P. T. Reynolds, Et. Al. Dec 2011

Veritas Observations Of Gamma-Ray Bursts Detected By Swift, P. T. Reynolds, Et. Al.

Physical Sciences Publications

We present the results of 16 Swift-triggered Gamma-ray burst (GRB) follow-up observations taken with the Very Energetic Radiation Imaging Telescope Array System (VERITAS) telescope array from 2007 January to 2009 June. The median energy threshold and response time of these observations were 260 GeV and 320 s, respectively. Observations had an average duration of 90 minutes. Each burst is analyzed independently in two modes: over the whole duration of the observations and again over a shorter timescale determined by the maximum VERITAS sensitivity to a burst with a t –1.5 time profile. This temporal model is characteristic of GRB afterglows …

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The Acs Survey Of Galactic Globular Clusters. Xi. The Three-Dimensional Orientation Of The Sagittarius Dwarf Spheroidal Galaxy And Its Globular Clusters, Michael H. H. Siegel, Steven R. Majewski, David R. Law, Ata Sarajedini, Aaron Dotter, A Marín-Franch, Brian Chaboyer Dec 2011

The Acs Survey Of Galactic Globular Clusters. Xi. The Three-Dimensional Orientation Of The Sagittarius Dwarf Spheroidal Galaxy And Its Globular Clusters, Michael H. H. Siegel, Steven R. Majewski, David R. Law, Ata Sarajedini, Aaron Dotter, A Marín-Franch, Brian Chaboyer

Dartmouth Scholarship

We use observations from the Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) study of Galactic globular clusters to investigate the spatial distribution of the inner regions of the disrupting Sagittarius dwarf spheroidal galaxy (Sgr). We combine previously published analyses of four Sgr member clusters located near or in the Sgr core (M54, Arp 2, Terzan 7, and Terzan 8) with a new analysis of diffuse Sgr material identified in the background of five low-latitude Galactic bulge clusters (NGC 6624, 6637, 6652, 6681, and 6809) observed as part of the ACS survey. By comparing the bulge cluster color-magnitude …

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A High-Eccentricity Component In The Double-Planet System Around Hd 163607 And A Planet Around Hd 164509*, Matthew J. Giguere, Debra A. Fischer, Andrew W. Howard, John A. Johnson, Gregory W. Henry, Jason T. Wright, Geoffrey W. Marcy, Howard Isaacson, Fengji Hou, Julien Spronck Dec 2011

A High-Eccentricity Component In The Double-Planet System Around Hd 163607 And A Planet Around Hd 164509*, Matthew J. Giguere, Debra A. Fischer, Andrew W. Howard, John A. Johnson, Gregory W. Henry, Jason T. Wright, Geoffrey W. Marcy, Howard Isaacson, Fengji Hou, Julien Spronck

Information Systems and Engineering Management Research Publications

We report the detection of three new exoplanets from Keck Observatory. HD 163607 is a metal-rich G5IV star with two planets. The inner planet has an observed orbital period of 75.29 ± 0.02 days, a semi-amplitude of 51.1 ± 1.4 m s−1, an eccentricity of 0.73 ± 0.02, and a derived minimum mass of MPsin i = 0.77 ± 0.02 MJup. This is the largest eccentricity of any known planet in a multi-planet system. The argument of periastron passage is 78.7 ± 2fdg0; consequently, the planet's closest approach to its parent star is very near the line of sight, leading …

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The Laboca Survey Of The Extended Chandra Deep Field-South: Clustering Of Submillimetre Galaxies, Ryan C. Hickox, J. L. Wardlow, Ian Smail, A. D. Myers Dec 2011

The Laboca Survey Of The Extended Chandra Deep Field-South: Clustering Of Submillimetre Galaxies, Ryan C. Hickox, J. L. Wardlow, Ian Smail, A. D. Myers

Dartmouth Scholarship

We present a measurement of the spatial clustering of submillimetre galaxies (SMGs) at z = 1–3. Using data from the 870 μm LABOCA submillimetre survey of the Extended Chandra Deep Field South, we employ a novel technique to measure the cross-correlation between SMGs and galaxies, accounting for the full probability distributions for photometric redshifts of the galaxies. From the observed projected two-point cross-correlation function we derive the linear bias and characteristic dark matter halo masses for the SMGs. We detect clustering in the cross-correlation between SMGs and galaxies at the > 4σ level. Accounting for the clustering of galaxies from their …

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A Search For The Transit Of Hd 168443b: Improved Orbital Parameters And Photometry, Genady Pilyavsky, Suvrath Mahadevan, Stephen R. Kane, Andrew W. Howard, David R. Ciardi, Chris De Pree, Diana Dragomir, Debra A. Fischer, Gregory W. Henry, Eric L. N. Jensen, Gregory Laughlin Dec 2011

A Search For The Transit Of Hd 168443b: Improved Orbital Parameters And Photometry, Genady Pilyavsky, Suvrath Mahadevan, Stephen R. Kane, Andrew W. Howard, David R. Ciardi, Chris De Pree, Diana Dragomir, Debra A. Fischer, Gregory W. Henry, Eric L. N. Jensen, Gregory Laughlin

Information Systems and Engineering Management Research Publications

The discovery of transiting planets around bright stars holds the potential to greatly enhance our understanding of planetary atmospheres. In this work we present the search for transits of HD 168443b, a massive planet orbiting the bright star HD 168443 (V = 6.92) with a period of 58.11 days. The high eccentricity of the planetary orbit (e = 0.53) significantly enhances the a priori transit probability beyond that expected for a circular orbit, making HD 168443 a candidate for our ongoing Transit Ephemeris Refinement and Monitoring Survey. Using additional radial velocities from Keck High Resolution Echelle Spectrometer, we refined the …

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Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv Singh, Marcos Rigol Dec 2011

Thermodynamics And Phase Transitions For The Heisenberg Model On The Pinwheel Distorted Kagome Lattice, Ehsan Khatami, Rajiv Singh, Marcos Rigol

Faculty Publications

We study the Heisenberg model on the pinwheel distorted kagome lattice as observed in the material Rb2Cu3SnF12. Experimentally relevant thermodynamic properties at finite temperatures are computed utilizing numerical linked-cluster expansions. We also develop a Lanczos-based, zero-temperature, numerical linked-cluster expansion to study the approach of the pinwheel distorted lattice to the uniform kagome-lattice Heisenberg model. We find strong evidence for a phase transition before the uniform limit is reached, implying that the ground state of the kagome-lattice Heisenberg model is likely not pinwheel dimerized and is stable to finite pinwheel-dimerizing perturbations.

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Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer Dec 2011

Lithium In The Upper Centaurus Lupus And Lower Centaurus Crux Subgroups Of Scorpius-Centaurus, Eric J. Bubar, Marc Schaeuble, Jeremy R. King, Eric E. Mamajek, John R. Stauffer

Publications

We utilize spectroscopically derived model atmosphere parameters and the Li i λ6104 subordinate line and the λ6708 doublet to derive lithium abundances for 12 members of the Upper Centaurus Lupus and Lower Centaurus Crux subgroups of the Scorpius–Centaurus OB Association. The results indicate any intrinsic Li scatter in our 0.9–1.4 M stars is limited to ∼0.15 dex, consistent with the lack of dispersion in 1.0 M stars in the 100 Myr Pleiades and 30–50 Myr IC 2391 and 2602 clusters. Both ab initio uncertainty estimates and the derived abundances themselves indicate that the λ6104 line yields abundances with equivalent or …

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Electron Screening And Disorder-Induced Heating In Ultracold Neutral Plasmas, Mary Elizabeth Lyon Dec 2011

Electron Screening And Disorder-Induced Heating In Ultracold Neutral Plasmas, Mary Elizabeth Lyon

Theses and Dissertations

Disorder-induced heating (DIH) is a nonequilibrium, ultrafast relaxation process that occurs when laser-cooled atoms are photoionized to make an ultracold plasma. Its effects dominate the ion motion during the first 100 ns of the plasma evolution. Using tools of atomic physics we study DIH with ns time resolution for different plasma densities and temperatures. By changing the frequency of the laser beam we use to probe the ions, we map out the time evolution of the velocity distribution. We can compare this to a fluorescence simulation in order to more clearly determine the relationship between the fluorescence signal and the …

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Astronomical Spectroscopy At The Cal Poly Observatory, Christopher James Almich Dec 2011

Astronomical Spectroscopy At The Cal Poly Observatory, Christopher James Almich

Physics

Embarking on the first ever astronomical spectroscopy project at the Cal Poly Observatory, I have tested the capabilities of our equipment. Our spectrograph, in conjunction with a telescope and CCD camera, is capable of making fairly precise measurements of absorption and emission lines with sub-nanometer precision. In my research I obtained a spectrum of Jupiter and was able to confidently identify a number of Fraunhofer solar absorption lines.

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Fabrication Of All-Inorganic Nanocrystal Solids Through Matrix Encapsulation Of Nanocrystal Arrays, Erich Kinder, Pavel Moroz, Geoffrey Diederich, Alexa Johnson, Maria Kirsanova, Alexander Nemchinov, Timothy O’Connor, Dan Roth, Mikhail Zamkov Dec 2011

Fabrication Of All-Inorganic Nanocrystal Solids Through Matrix Encapsulation Of Nanocrystal Arrays, Erich Kinder, Pavel Moroz, Geoffrey Diederich, Alexa Johnson, Maria Kirsanova, Alexander Nemchinov, Timothy O’Connor, Dan Roth, Mikhail Zamkov

Physics and Astronomy Faculty Publications

A general strategy for low-temperature processing of colloidal nanocrystals into all-inorganic films is reported. The present methodology goes beyond the traditional ligand-interlinking scheme and relies on encapsulation of morphologically defined nanocrystal arrays into a matrix of a wide-band gap semiconductor, which preserves optoelectronic properties of individual nanoparticles while rendering the nanocrystal film photoconductive. Fabricated solids exhibit excellent thermal stability, which is attributed to the heteroepitaxial structure of nanocrystal matrix interfaces, and show compelling light-harvesting performance in prototype solar cells.

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First Mover: Otto Struve And The Use Of Scientific Capital In Astrophysics, 1921–1950, Erik Paul Norquest Dec 2011

First Mover: Otto Struve And The Use Of Scientific Capital In Astrophysics, 1921–1950, Erik Paul Norquest

Theses and Dissertations - UTB/UTPA

Otto Struve (1897-1963) came to the United States in 1921 and became one of the dominant personalities in the field of astrophysics. Struve’s career made him, in the words of sociologist Pierre Bourdieu, a “first mover” in a scientific field that was firmly engaged in the process of what Thomas Kuhn called “normal science.” Struve pulled astrophysics further away from its empirical roots in categorization and made it more like physics in its unification of theory and observation. The primary way that he accomplished this was through his administration of Yerkes and McDonald observatories, where he brought in theorists to …

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A Search For And Characterization Of Young Stellar Objects In N206, An H Ii Complex In The Large Magellanic Cloud, Tabitha Christi Buehler Dec 2011

A Search For And Characterization Of Young Stellar Objects In N206, An H Ii Complex In The Large Magellanic Cloud, Tabitha Christi Buehler

Theses and Dissertations

I have identified 51 young stellar object candidates in N206, an H II complex in the nearby Large Magellanic Cloud galaxy. Using archival images from the Spitzer Space Telescope, supplemented with other infrared and optical images, I located point sources in this region. I distinguished possible young stellar objects based on their spectral energy distributions, morphologies, and locations in color-magnitude space. I classified the young stellar object candidates based on their likelihood of being young stellar objects and based on their apparent evolutionary stages. The spatial distribution of these candidates in N206 indicates that star formation is being triggered …

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A Gravitational Wave Observatory Operating Beyond The Quantum Shot-Noise Limit: Squeezed Light In Application, J. Abadie, B. P. Abbott, T. D. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Joseph D. Romano Dec 2011

A Gravitational Wave Observatory Operating Beyond The Quantum Shot-Noise Limit: Squeezed Light In Application, J. Abadie, B. P. Abbott, T. D. Abbott, Matthew Benacquista, Teviet Creighton, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Volker Quetschke, Joseph D. Romano

Physics & Astronomy Faculty Publications

Around the globe several observatories are seeking the first direct detection of gravitational waves (GWs). These waves are predicted by Einstein's general theory of relativity(1) and are generated, for example, by black-hole binary systems(2). Present GW detectors are Michelson-type kilometre-scale laser interferometers measuring the distance changes between mirrors suspended in vacuum. The sensitivity of these detectors at frequencies above several hundred hertz is limited by the vacuum (zero-point) fluctuations of the electromagnetic field. A quantum technology-the injection of squeezed light(3)-offers a solution to this problem. Here we demonstrate the squeezed-light enhancement of GEO 600, which will be the GW observatory …

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Investigating Turbulence Transport In The Heliosphere, Lauren Kahre Nov 2011

Investigating Turbulence Transport In The Heliosphere, Lauren Kahre

Honors Capstone Projects and Theses

No abstract provided.

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Retired A Stars And Their Companions. Vii. 18 New Jovian Planets, John Asher Johnson, Christian Clanton, Andrew W. Howard, Brendan P. Bowler, Gregory W. Henry, Geoffrey W. Marcy, Justin R. Crepp, Michael Endl, William D. Cochran, Phillip J. Macqueen, Jason T. Wright, Howard Isaacson Nov 2011

Retired A Stars And Their Companions. Vii. 18 New Jovian Planets, John Asher Johnson, Christian Clanton, Andrew W. Howard, Brendan P. Bowler, Gregory W. Henry, Geoffrey W. Marcy, Justin R. Crepp, Michael Endl, William D. Cochran, Phillip J. Macqueen, Jason T. Wright, Howard Isaacson

Information Systems and Engineering Management Research Publications

We report the detection of 18 Jovian planets discovered as part of our Doppler survey of subgiant stars at Keck Observatory, with follow-up Doppler and photometric observations made at McDonald and Fairborn Observatories, respectively. The host stars have masses 0.927 ⩽ M⋆/M☉ ⩽ 1.95, radii 2.5 ⩽ R⋆/R☉ ⩽ 8.7, and metallicities −0.46 ⩽ [Fe/H] ⩽+0.30. The planets have minimum masses 0.9 MJup ⩽ MPsin i ≲ 13 MJup and semimajor axes a ⩾ 0.76 AU. These detections represent a 50% increase in the number of planets known to orbit stars more massive than 1.5 M☉ and provide valuable additional …

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Absolute Properties Of The Highly Eccentric, Solar-Type Eclipsing Binary Hd 74057, James R. Sowell, Gregory W. Henry, Francis C. Fekel Nov 2011

Absolute Properties Of The Highly Eccentric, Solar-Type Eclipsing Binary Hd 74057, James R. Sowell, Gregory W. Henry, Francis C. Fekel

Information Systems and Engineering Management Research Publications

We have obtained Strömgren b and y differential photometric observations of the solar-type eclipsing binary HD 74057 plus follow-up high-resolution, red wavelength spectroscopic observations. The system has an orbital period of 31.2198 days, a high eccentricity of 0.47, and is seen almost exactly edge on with an inclination of 89fdg8. The two main-sequence G0 stars are nearly identical in all physical characteristics. We used the Wilson–Devinney program to obtain a simultaneous solution of our photometric and spectroscopic observations. The resulting masses of the components are M1 = 1.138 ± 0.003 M☉ and M2 = 1.131 ± 0.003 M☉, and the …

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Orbital Separation Amplification In Fragile Binaries With Evolved Components, K. B. Johnston, Terry D. Oswalt Nov 2011

Orbital Separation Amplification In Fragile Binaries With Evolved Components, K. B. Johnston, Terry D. Oswalt

Publications

The secular stellar mass-loss causes an amplification of the orbital separation in fragile, common proper motion, binary systems with separations of the order of 1000 A.U. In these systems, companions evolve as two independent coeval stars as they experience negligible mutual tidal interactions or mass transfer. We present models for how post-main sequence mass-loss statistically distorts the frequency distribution of separations in fragile binaries. These models demonstrate the expected increase in orbital seapration resulting from stellar mass-loss, as well as a perturbation of associated orbital parameters. Comparisons between our models and observations resulting from the Luyten survey of wide visual …

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The Stellar-Activity–Rotation Relationship And The Evolution Of Stellar Dynamos, Nicholas J. Wright, Jeremy J. Drake, Eric E. Mamajek, Gregory W. Henry Nov 2011

The Stellar-Activity–Rotation Relationship And The Evolution Of Stellar Dynamos, Nicholas J. Wright, Jeremy J. Drake, Eric E. Mamajek, Gregory W. Henry

Information Systems and Engineering Management Research Publications

We present a sample of 824 solar and late-type stars with X-ray luminosities and rotation periods. This is used to study the relationship between rotation and stellar activity and derive a new estimate of the convective turnover time. From an unbiased subset of this sample the power-law slope of the unsaturated regime, LX/Lbol∝Roβ, is fit as β = −2.70 ± 0.13. This is inconsistent with the canonical β = −2 slope to a confidence of 5σ, and argues for an additional term in the dynamo number equation. From a simple scaling analysis this implies ΔΩ/Ω∝Ω0.7, i.e., the differential rotation of …

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V344 Lyrae: A Touchstone Su Uma Cataclysmic Variable In The Kepler Field, Matt A. Wood, Martin D. Still, Steve B. Howell, John K. Cannizzo, Alan P. Smale Nov 2011

V344 Lyrae: A Touchstone Su Uma Cataclysmic Variable In The Kepler Field, Matt A. Wood, Martin D. Still, Steve B. Howell, John K. Cannizzo, Alan P. Smale

Aerospace, Physics, and Space Science Faculty Publications

We report on the analysis of the Kepler short-cadence (SC) light curve of V344 Lyr obtained during 2009 June 20 through 2010 March 19 (Q2-Q4). The system is an SU UMa star showing dwarf nova (DN) outbursts and superoutbursts, and promises to be a touchstone for CV studies for the foreseeable future. The system displays both positive and negative superhumps with periods of 2.20 and 2.06 hr, respectively, and we identify an orbital period of 2.11 hr. The positive superhumps have a maximum amplitude of ~0.25 mag, the negative superhumps have a maximum amplitude of ~0.8 mag, and the orbital …

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Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin Nov 2011

Application Of Asymptotic Expansions For Maximum Likelihood Estimators' Errors To Gravitational Waves From Inspiraling Binary Systems: The Network Case, Salvatore Vitale, Michele Zanolin

Publications

This paper describes the most accurate analytical frequentist assessment to date of the uncertainties in the estimation of physical parameters from gravitational waves generated by nonspinning binary systems and Earth-based networks of laser interferometers. The paper quantifies how the accuracy in estimating the intrinsic parameters mostly depends on the network signal to noise ratio (SNR), but the resolution in the direction of arrival also strongly depends on the network geometry. We compare results for 6 different existing and possible global networks and two different choices of the parameter space. We show how the fraction of the sky where the one …

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Time Evolution Of The Reverse Shock In Sn 1006, P. Frank Winkler, Andrew J. S. Hamilton, Knox S. Long, Robert A. Fesen Nov 2011

Time Evolution Of The Reverse Shock In Sn 1006, P. Frank Winkler, Andrew J. S. Hamilton, Knox S. Long, Robert A. Fesen

Dartmouth Scholarship

The Schweizer-Middleditch star, located behind the SN 1006 remnant and near its center in projection, provides the opportunity to study cold, expanding ejecta within the SN 1006 shell through UV absorption. Especially notable is an extremely sharp red edge to the Si II 1260 Å feature, which stems from the fastest moving ejecta on the far side of the SN 1006 shell—material that is just encountering the reverse shock. Comparing Hubble Space Telescope far-UV spectra obtained with the Cosmic Origins Spectrograph in 2010 and with the Space Telescope Imaging Spectrograph in 1999, we have measured the change in this feature …

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The Polylogarithm And The Lambert W Functions In Thermoelectrics, Muralikrishna Molli, Kamisetty Venkataramaniah, Sree Ram Valluri Nov 2011

The Polylogarithm And The Lambert W Functions In Thermoelectrics, Muralikrishna Molli, Kamisetty Venkataramaniah, Sree Ram Valluri

Physics and Astronomy Publications

In this work, we determine the conditions for the extremum of the figure of merit, theta2, in a degenerate semiconductor for thermoelectric (TE) applications. We study the variation of the function theta2 with respect to the reduced chemical potential mu* using relations involving polylogarithms of both integral and nonintegral orders. We present the relevant equations for the thermopower, thermal, and electrical conductivities that result in optimizing theta2 and obtaining the extremum equations. We discuss the different cases that arise for various values of r, which depends on the type of carrier scattering mechanism present in the …

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Distance Scale Zero Points From Galactic Rr Lyrae Star Parallaxes, G. Fritz Benedict, Barbara E. Mcarthur, Michael W. Feast, Thomas G. Barnes, Thomas E. Harrison, Jacob L. Bean, John W. Menzies, Brian Chaboyer Nov 2011

Distance Scale Zero Points From Galactic Rr Lyrae Star Parallaxes, G. Fritz Benedict, Barbara E. Mcarthur, Michael W. Feast, Thomas G. Barnes, Thomas E. Harrison, Jacob L. Bean, John W. Menzies, Brian Chaboyer

Dartmouth Scholarship

We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars—five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and κ Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 ± 0.16 mas; XZ Cyg, 1.67 ± 0.17 mas; SU Dra, 1.42 ± 0.16 mas; RR Lyr, 3.77 ± 0.13 mas; UV Oct, 1.71 ± 0.10 mas; VY Pyx, 6.44 ± 0.23 …

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Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol Nov 2011

Thermodynamics Of Strongly Interacting Fermions In Two-Dimensional Optical Lattices, Ehsan Khatami, Marcos Rigol

Faculty Publications

We study finite-temperature properties of strongly correlated fermions in two-dimensional optical lattices by means of numerical linked cluster expansions, a computational technique that allows one to obtain exact results in the thermodynamic limit. We focus our analysis on the strongly interacting regime, where the on-site repulsion is of the order of or greater than the band width. We compute the equation of state, double occupancy, entropy, uniform susceptibility, and spin correlations for temperatures that are similar to or below the ones achieved in current optical lattice experiments. We provide a quantitative analysis of adiabatic cooling of trapped fermions in two …

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Book Review: The Cambridge Atlas Of Herschel Objects, T. D. Oswalt Nov 2011

Book Review: The Cambridge Atlas Of Herschel Objects, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of The Cambridge Atlas of Herschel Objects by James Mullaney and Wil Tirion Cambridge, 2011 183p, 0521138175 $35.00, 9780521138178 $35.00.

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Thick Disks Of Edge-On Galaxies Seen Through The Spitzer Survey Of Stellar Structure In Galaxies (S4g) : Lair Of Missing Baryons?, Sebastien Comeron, Bruce G. Elmegreen, Johan H. Knapen, Heikki Salo, Eija Laurikainen, Jarkko Laine, E. Athanassoula, Albert Bosma, Kartik Sheth, Michael W. Regan, Joannah L. Hinz, Armando Gil De Paz, Karin Menendez-Delmestre, Trisha Mizusawa, Juan Carlos Munoz-Mateos, Mark Seibert, Taehyun Kim, Debra M. Elmegreen, Dimitri A. Gadotti, Luis C. Ho, Benne W. Holwerda, Jani Lappalainen, Eva Schinnerer, Ramin Skibba Nov 2011

Thick Disks Of Edge-On Galaxies Seen Through The Spitzer Survey Of Stellar Structure In Galaxies (S4g) : Lair Of Missing Baryons?, Sebastien Comeron, Bruce G. Elmegreen, Johan H. Knapen, Heikki Salo, Eija Laurikainen, Jarkko Laine, E. Athanassoula, Albert Bosma, Kartik Sheth, Michael W. Regan, Joannah L. Hinz, Armando Gil De Paz, Karin Menendez-Delmestre, Trisha Mizusawa, Juan Carlos Munoz-Mateos, Mark Seibert, Taehyun Kim, Debra M. Elmegreen, Dimitri A. Gadotti, Luis C. Ho, Benne W. Holwerda, Jani Lappalainen, Eva Schinnerer, Ramin Skibba

Faculty and Staff Scholarship

Most, if not all, disk galaxies have a thin (classical) disk and a thick disk. In most models thick disks are thought to be a necessary consequence of the disk formation and/or evolution of the galaxy. We present the results of a study of the thick disk properties in a sample of carefully selected edge-on galaxies with types ranging from T = 3 to T = 8. We fitted one-dimensional luminosity profiles with physically motivated functions—the solutions of two stellar and one gaseous isothermal coupled disks in equilibrium—which are likely to yield more accurate results than other functions used in …

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Infrared And Upconversion Spectroscopic Studies Of High Er3+Content Transparent Yag Ceramic, M. Pokhrel, G. A. Kumar, P. Samuel, K. I. Ueda, T. Yanagitani, H. Yagi, D. K. Sardar Nov 2011

Infrared And Upconversion Spectroscopic Studies Of High Er3+Content Transparent Yag Ceramic, M. Pokhrel, G. A. Kumar, P. Samuel, K. I. Ueda, T. Yanagitani, H. Yagi, D. K. Sardar

Physics & Astronomy Faculty Publications

In this article, we report the detailed spectroscopic studies of high Er3+content (50%) transparent YAG ceramic co-doped with nominal Cr3+ content (0.1 mol %). Various radiative and non-radiative spectroscopic properties such as radiative decay time, fluorescence branching ratio, emission/absorption cross sections, internal radiative quantum yields of the infrared and the upconverted emission bands are explored using standard experimental and theoretical methods and compared with YAG single crystal. Results show that although the non-radiative losses are high for 50% Er doped ceramic; several radiative spectral properties are almost in agreement with those for the single crystal YAG. Furthermore, because of the …

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Absolute Properties Of The Eclipsing Binary Star Hy Virginis, Claud H. Sandberg Lacy, Francis C. Fekel Oct 2011

Absolute Properties Of The Eclipsing Binary Star Hy Virginis, Claud H. Sandberg Lacy, Francis C. Fekel

Information Systems and Engineering Management Research Publications

HY Vir is found to be a double-lined F0m+F5 binary star with relatively shallow (0.3 mag) partial eclipses. Previous studies of the system are improved with 7509 differential photometric observations from the URSA WebScope and 8862 from the NFO WebScope, and 68 high-resolution spectroscopic observations from the Tennessee State University 2 m automatic spectroscopic telescope, and the 1 m coudé-feed spectrometer at Kitt Peak National Observatory. Very accurate (better than 0.5%) masses and radii are determined from analysis of the new light curves and radial velocity curves. Theoretical models match the absolute properties of the stars at an age of …

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The Properties Of The Stellar Nuclei With The Host Galaxy Morphology In The Acsvcs, Hyun-Chul Lee Oct 2011

The Properties Of The Stellar Nuclei With The Host Galaxy Morphology In The Acsvcs, Hyun-Chul Lee

Physics & Astronomy Faculty Publications

We have revisited the ACS Virgo Cluster Survey (ACSVCS), a Hubble Space Telescope program to obtain ACS/WFC g and z bands imaging for a sample of 100 early-type galaxies in the Virgo Cluster. In this study, we examine 51 nucleated early-type galaxies in the ACSVCS in order to look into the relationship between the photometric and structural properties of stellar nuclei and their host galaxies. We morphologically dissect galaxies into five classes. We note that (1) the stellar nuclei of dwarf early-type galaxies (dS0, dE, and dE,N) are generally fainter and bluer with g > 18.95 and (g-z) < 1.40 compared to some brighter and redder counterparts of the ellipticals (E) and lenticular galaxies (S0), (2) the g-band half-light radii of stellar nuclei of all dwarf early-type galaxies (dS0, dE, and dE,N) are smaller than 20 pc and their average is about 4 pc, and (3) the colors of red stellar nuclei with (g - z) > 1.40 in bright …

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