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6,438 full-text articles. Page 196 of 196.

A Spitzer Search For Planetary-Mass Brown Dwarfs With Circumstellar Disks: Candidate Selection, Paul M. Harvey, Daniel T. Jaffe, Katelyn N. Allers, Michael Liu 2010 Bucknell University

A Spitzer Search For Planetary-Mass Brown Dwarfs With Circumstellar Disks: Candidate Selection, Paul M. Harvey, Daniel T. Jaffe, Katelyn N. Allers, Michael Liu

Faculty Journal Articles

No abstract provided.


On The Origin Of The Highest Redshift Gamma-Ray Bursts, Krzysztof Belczynski, Daniel E. Holz, Chris L. Fryer, Edo Berger, Dieter H. Hartmann, Brain O'Shea 2010 Los Alamos National Laboratory & Astronomical Observatory, University of Warsaw &

On The Origin Of The Highest Redshift Gamma-Ray Bursts, Krzysztof Belczynski, Daniel E. Holz, Chris L. Fryer, Edo Berger, Dieter H. Hartmann, Brain O'Shea

Publications

GRB 080913 and GRB 090423 are the most distant gamma-ray bursts (GRBs) known to date, with spectroscop-ically determined redshifts of z = 6.7 and z = 8.1, respectively. The detection of bursts at this early epoch of the universe significantly constrains the nature of GRBs and their progenitors. We perform population synthesis studies of the formation and evolution of early stars, and calculate the resulting formation rates of short- and long-duration GRBs at high redshift. The peak of the GRB rate from Population II stars occurs at z ∼ 7for a model with efficient/fast mixing of metals, while it is ...


Limit On Continuous Neutrino Emission From Neutron Stars, Itzhak Goldman, Shmuel Nussinov 2010 Afeka College of Engineering

Limit On Continuous Neutrino Emission From Neutron Stars, Itzhak Goldman, Shmuel Nussinov

Mathematics, Physics, and Computer Science Faculty Articles and Research

The timing data of the binary pulsar PSR1913+16, are used to establish an upper limit on the rate of continuous neutrino emission from neutron stars. Neutrino emission from each of the neutron stars of the binary system, increases the star binding energy and thus translates to a decrease in their masses. This in turn implies an increase with time of the binary period. Using the pulsar data we obtain an upper limit on the allowed rate of mass reduction: vertical bar M vertical bar < 1.1 x 10(-12) yr(-1) M, where M is the total mass of the binary. This constrains exotic nuclear equations of state that predict continuous neutrino emissions. The limit applies also to other channels of energy loss, e. g. axion emission. Continued timing measurements of additional binary pulsars, should yield a stronger limit in the future.


High-Resolution Cavity-Enhanced Spectroscopy Of Molecular Ion Beams, Manori Perera, Andrew Mills, Brian Siller, Michael Porambo, Kyle Crabtree, Carrie Kauffman, Holger Kreckel, Benjamin McCall 2010 Illinois Wesleyan University

High-Resolution Cavity-Enhanced Spectroscopy Of Molecular Ion Beams, Manori Perera, Andrew Mills, Brian Siller, Michael Porambo, Kyle Crabtree, Carrie Kauffman, Holger Kreckel, Benjamin Mccall

Scholarship

Molecular ions play a pivotal role in the chemistry of the interstellar medium due to their high reactivity even at low temperature. To identify these ions in interstellar space, it is essential to obtain high resolution laboratory spectra of potential interstellar ions for comparison to observational data. At the University of Illinois, we are developing a Sensitive, Cooled, Resolved Ion BEam Spectrometer (SCRIBES) that will allow us to obtain high resolution infrared direct absorption spectra of rotationally cold molecular ions in the absence of neutral molecules. This instrument can overcome many of the problems that arise when using other spectroscopic ...


Conventions, Definitions, Identities, And Other Useful Formulae, Robert A. McNees IV 2010 Loyola University Chicago

Conventions, Definitions, Identities, And Other Useful Formulae, Robert A. Mcnees Iv

Physics: Faculty Publications and Other Works

As the name suggests, these notes contain a summary of important conventions, definitions, identities, and various formulas that I often refer to. They may prove useful for researchers working in General Relativity, Supergravity, String Theory, Cosmology, and related areas.


Relations Relevant To The One Body Reduction Of The Gravitational Two Body Problem, Eric Addison 2009 Utah State University

Relations Relevant To The One Body Reduction Of The Gravitational Two Body Problem, Eric Addison

Eric Addison

The one body reduction of the two body problem is outlined along with several important relations. It is verified that both masses in a binary system orbit around the common center of mass.


The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John Cannon, Korey Haynes, Hans Most, John Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling 2009 Macalester College

The Stellar And Gaseous Contents Of The Orion Dwarf Galaxy, John Cannon, Korey Haynes, Hans Most, John Salzer, Kaitlin Haugland, Jillian Scudder, Arthur Sugden, Jacob Weindling

John Cannon

No abstract provided.


Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission Features In Nearby, Low Metallicity, Star-Forming Galaxies, Korey Haynes, John Cannon, Evan Skillman, Dale Jackson, Robert Gehrz 2009 Macalester College

Spatially Resolved Polycyclic Aromatic Hydrocarbon Emission Features In Nearby, Low Metallicity, Star-Forming Galaxies, Korey Haynes, John Cannon, Evan Skillman, Dale Jackson, Robert Gehrz

John Cannon

No abstract provided.


Instantaneous Velocities Of A Two Body Orbit, Eric Addison 2009 Utah State University

Instantaneous Velocities Of A Two Body Orbit, Eric Addison

Eric Addison

This short note will derive expressions for the instantaneous velocity of the components in a two-body elliptical Keplerian orbit.


Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison 2009 Utah State University

Derivation Of Initial Velocities For A Two-Body Orbit In The Barycenter Frame, Eric Addison

Eric Addison

The readily available information for two body orbits generally refers to the one dimensional, reduced mass case. Information about initial conditions in the barycenter frame is not easily found. In order to derive the initial velocities required for a two-body orbit in the barycenter frame, the momentum of the reduced mass can be used.


Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson 2009 University of Massachusetts - Amherst

Origins Of The Extragalactic Background At 1mm From A Combined Analysis Of The Aztec And Mambo Data In Goods-N, Kyle Penner, Alexandra Pope, Edward L. Chapin, Thomas R. Greve, Frank Bertoldi, Mark Brodwin, Ranga-Ram Chary, Christopher J, Conselice, Kristen Coppin, Mauro Giavalisco, David H. Hughes, Rob J. Ivison, Thushara Perera, Douglas Scott, Kimberly Scott, Grant Wilson

Thushara A. Perera

We present a study of the cosmic infrared background, which is a measure of the dust obscured activity in all galaxies in the Universe. We venture to isolate the galaxies responsible for the background at 1mm; with spectroscopic and photometric redshifts we constrain the redshift distribution of these galaxies. We create a deep 1.16mm map (sigma ~ 0.5mJy) by combining the AzTEC 1.1mm and MAMBO 1.2mm datasets in GOODS-N. This combined map contains 41 secure detections, 13 of which are new. By averaging the 1.16mm flux densities of individually undetected galaxies with 24um flux densities > 25uJy ...


Binary Tidal Disruption Radius, Eric Addison 2009 Utah State University

Binary Tidal Disruption Radius, Eric Addison

Eric Addison

An expression for the tidal disruption radius of a binary system is calculated.


The Globular Cluster System Of Ngc 1399. V. Dynamics Of The Cluster System Out To 80 Kpc, Y. Schuberth, T. Richtler, M. Hilker, B. Dirsch, L. Bassino, Aaron J. Romanowsky, L. Infante 2009 Universidad Nacional de La Plata

The Globular Cluster System Of Ngc 1399. V. Dynamics Of The Cluster System Out To 80 Kpc, Y. Schuberth, T. Richtler, M. Hilker, B. Dirsch, L. Bassino, Aaron J. Romanowsky, L. Infante

Aaron J. Romanowsky

Globular clusters (GCs) are tracers of the gravitational potential of their host galaxies. Moreover, their kinematic properties may provide clues for understanding the formation of GC systems and their host galaxies. We use the largest set of GC velocities obtained so far of any elliptical galaxy to revise and extend the previous investigations (Richtler et al. 2004) of the dynamics of NGC 1399, the central dominant galaxy of the nearby Fornax cluster of galaxies. The GC velocities are used to study the kinematics, their relation with population properties, and the dark matter halo of NGC 1399. We have obtained 477 ...


Central Dark Matter Content Of Early-Type Galaxies: Scaling Relations And Connections With Star Formation Histories, N. R. Napolitano, Aaron J. Romanowsky, A. J. Tortora 2009 San Jose State University

Central Dark Matter Content Of Early-Type Galaxies: Scaling Relations And Connections With Star Formation Histories, N. R. Napolitano, Aaron J. Romanowsky, A. J. Tortora

Aaron J. Romanowsky

We examine correlations between masses, sizes and star formation histories for a large sample of low-redshift early-type galaxies, using a simple suite of dynamical and stellar population models. We confirm an anticorrelation between the size and stellar age and go on to survey for trends with the central content of dark matter (DM). An average relation between the central DM density and galaxy size of 〈ρDM〉∝R−2eff provides the first clear indication of cuspy DM haloes in these galaxies – akin to standard Λ cold dark matter haloes that have undergone adiabatic contraction. The DM density scales with galaxy mass ...


The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. G. Gayley, R. Ignace 2009 East Tennessee State University

The Zeeman Effect In The Sobolev Approximation Ii. Radial Split Monopole Fields And The ‘Heartbeat’ Stokes V Profile., K. G. Gayley, R. Ignace

Richard Ignace

We calculate the circularly polarized Stokes V(λ) profile for emission lines, formed in hot-star winds threaded with a weak radial magnetic field. For simplicity, the field is treated as a split monopole under the assumptions that it has been radially combed by the wind, and rotation is not playing a central role. Invoking the weak-field approximation, we find that the V(λ) profile has a characteristic “heartbeat” shape exhibiting multiple sign inversions, which might be mistaken for noise in the absence of theoretical guidance. We also conclude that there is a tendency for the V(λ) profile to integrate ...


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