Telescopes, Robots And Computers: Using Technology To See The Cosmos,
2011
Utah State University
Telescopes, Robots And Computers: Using Technology To See The Cosmos, Shane L. Larson
Public Talks
No abstract provided.
Confirmation Of 1rxs J165443.5–191620 As An Intermediate Polar And Its Orbital And Spin Periods,
2011
Radboud University Nijmegen
Confirmation Of 1rxs J165443.5–191620 As An Intermediate Polar And Its Orbital And Spin Periods, S. Scaringi, S. Connolly, J. Patterson, J. R. Thorstensen
Dartmouth Scholarship
We investigate the physical nature of the X-ray emitting source 1RXS J165443.5−191620 through optical photometry and time-resolved spectroscopy. Optical photometry is obtained from a variety of telescopes all over the world spanning ≈27 days. Additionally, time-resolved spectroscopy is obtained from the MDM observatory.
New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. Vi. Hd 24623 And V923 Scorpii,
2011
Tennessee State University
New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. Vi. Hd 24623 And V923 Scorpii, Francis C. Fekel, Michael H. Williamson, Gregory W. Henry
Information Systems and Engineering Management Research Publications
Using new radial velocities obtained at KPNO and Fairborn Observatory, we have determined improved spectroscopic orbits for two double-lined F-type binaries, HD 24623 and V923 Sco. The orbital periods are 19.66304 and 34.8386 days, respectively, so it is not surprising that their orbits have relatively high eccentricities of nearly 0.5. The orbital dimensions (a1sin i and a2sin i) and minimum masses (m1sin 3i and m2sin 3i) have accuracies of 0.2% or better. Extensive photometry of HD 24623 with the T4 0.75 m automatic photometric telescope at Fairborn Observatory shows no evidence of eclipses. Instead, a very weak reflection effect is …
The Unusual Protoplanetary Disk Around The T Tauri Star Et Chamaeleontis,
2011
University of Vienna
The Unusual Protoplanetary Disk Around The T Tauri Star Et Chamaeleontis, P Woitke, B Riaz, G Duchene, I Pascucci, A Ran Lyo, W.R.F. Dent, N Phillips, W F. Thi, F Menard, G J. Herczeg, E Bergin, A Brown, A Mora, I Kamp, G Aresu, Sean D. Brittain, I De Gregorio-Monsalvo, G Sandell
Publications
We present new continuum and line observations, along with modelling, of the faint (6−8) Myr old T Tauri star ETCha belonging to the η Chamaeleontis cluster. We have acquired Herschel/PACS photometric fluxes at 70 μm and 160 μm, as well as a detection of the [OI] 63 μm fine-structure line in emission, and derived upper limits for some other far-IR OI, CII, CO and o-H2O lines. These observations were carried out in the frame of the open time key programme GASPS, where ETCha was selected as one of the science demonstration phase targets. The Herschel data is complemented by new …
Novel Test Of Modified Newtonian Dynamics With Gas Rich Galaxies,
2011
Case Western Reserve University
Novel Test Of Modified Newtonian Dynamics With Gas Rich Galaxies, Stacy S. Mcgaugh
Faculty Scholarship
The current cosmological paradigm, the cold dark matter model with a cosmological constant, requires that the mass-energy of the Universe be dominated by invisible components: dark matter and dark energy. An alternative to these dark components is that the law of gravity be modified on the relevant scales. A test of these ideas is provided by the baryonic Tully-Fisher relation (BTFR), an empirical relation between the observed mass of a galaxy and its rotation velocity. Here, I report a test using gas rich galaxies for which both axes of the BTFR can be measured independently of the theories being tested …
Cosmic-Ray Modulation By The Global Merged Interaction Region In The Heliosheath,
2011
Florida Institute of Technology
Cosmic-Ray Modulation By The Global Merged Interaction Region In The Heliosheath, Xi Luo, Ming Zhang, Hamid K. Rassoul, Nikolai V. Pogorelov
Aerospace, Physics, and Space Science Faculty Publications
It was found by Voyager 1 and Voyager 2 that the Global Merged Interaction Region (GMIR) still has effects on cosmic-ray transport in the heliosheath. The GMIR produced by the intense solar activities of 2005 September propagated into the heliosheath in 2006, causing several decreases in the cosmic-ray flux at Voyager 1. Motivated by these observations, we investigate cosmic-ray modulation by the GMIR in the heliosheath using a three-dimensional Galactic cosmic-ray modulation code that includes the drift effect, termination shock, and a propagating GMIR. The simulation reproduces all major modulation features found by previous cosmic-ray observations in the supersonic solar …
Constraining The Coalescence Rate Of Supermassive Black-Hole Binaries Using Pulsar Timing,
2011
University of Texas Rio Grande Valley
Constraining The Coalescence Rate Of Supermassive Black-Hole Binaries Using Pulsar Timing, Z. L. Wen, F. A. Jenet, D. Yardley, G. B. Hobbs, R. N. Manchester
Physics & Astronomy Faculty Publications
Pulsar timing observations are used to place constraints on the rate of coalescence of supermassive black-hole (SMBH) binaries as a function of mass and redshift. In contrast to the indirect constraints obtained from other techniques, pulsar timing observations provide a direct constraint on the black-hole merger rate. This is possible since pulsar timing is sensitive to the gravitational waves (GWs) emitted by these sources in the final stages of their evolution. We find that upper bounds calculated from the recently published Parkes Pulsar Timing Array data are just above theoretical predictions for redshifts below 10. In the future, with improved …
The White Dwarf Age Of Nfc 2477,
2011
Space Telescope Science Institute
The White Dwarf Age Of Nfc 2477, Elizabeth J. Jeffery, Ted Von Hippel, Et Al.
Publications
We present deep photometric observations of the open cluster NGC 2477 using HST/WFPC2. By identifying seven cluster white dwarf candidates, we present an analysis of the white dwarf age of this cluster, using both the traditional method of fitting isochrones to the white dwarf cooling sequence, and by employing a new Bayesian statistical technique that has been developed by our group. This new method performs an objective, simultaneous model fit of the cluster and stellar parameters (namely, age, metallicity, distance, reddening, as well as individual stellar masses, mass ratios, and cluster membership) to the photometry. Based on this analysis, …
Impact Of A Finite-Temperature Equation Of State On Neutron Stars,
2011
Brigham Young University - Provo
Impact Of A Finite-Temperature Equation Of State On Neutron Stars, Christian D. Draper
Theses and Dissertations
In this research, we study how a finite-temperature nuclear equation of state suitable for astrophysical simulations impacts the oscillation modes of neutron stars. We chose the Shen equation of state (EOS) because it accurately describes both stable and unstable nuclei as well as nuclear incompressibilities. I modified the existing MHD code at BYU, the HAD code, to call a lookup table for the Shen EOS for use at run time, and added a Newton-Raphson method algorithm to convert conserved variables to primitive variables. The algorithm was tested and verified by evolving a stable neutron star for several dynamical times and …
Einstein's Life: Advanced Science And Life In The Modern Age,
2011
Utah State University
Einstein's Life: Advanced Science And Life In The Modern Age, Shane L. Larson
Public Talks
No abstract provided.
High-Quality Broadband Bvri Photometry Of Benchmark Open Clusters,
2011
Brigham Young University - Provo
High-Quality Broadband Bvri Photometry Of Benchmark Open Clusters, Michael Deloss Joner
Theses and Dissertations
Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to archival work and shown to be both accurate and precise. The careful use of a …
A Study Of Differential Rotation On Ii Pegasi Via Photometric Starspot Imaging,
2011
Ohio Wesleyan University
A Study Of Differential Rotation On Ii Pegasi Via Photometric Starspot Imaging, Rachael M. Roettenbacher, Robert O. Harmon, Nalin Vutisalchavakul, Gregory W. Henry
Information Systems and Engineering Management Research Publications
We present the results of a study of differential rotation on the K2 IV primary of the RS CVn binary II Pegasi (HD 224085) performed by inverting light curves to produce images of the dark starspots on its surface. The data were obtained in the standard Johnson B and V filter passbands via the Tennessee State University T3 0.4 m Automated Photometric Telescope from JD 2447115.8086–2455222.6238 (1987 November 16–2010 January 26). The observations were subdivided into 79 data sets consisting of pairs of B and V light curves, which were then inverted using a constrained nonlinear inversion algorithm that makes …
Three Channel Polarimetric Based Data Deconvolution,
2011
Air Force Institute of Technology
Three Channel Polarimetric Based Data Deconvolution, Kurtis G. Engelson
Theses and Dissertations
A three channel polarimetric deconvolution algorithm was developed to mitigate the degrading effects of atmospheric turbulence in astronomical imagery. Tests were executed using both simulation and laboratory data. The resulting efficacy of the three channel algorithm was compared to a recently developed two channel approach under identical conditions ensuring a fair comparison amongst both algorithms. Two types of simulations were performed. The first was a binary star simulation to compare resulting resolutions between the three and two channel algorithms. The second simulation measured how effective both algorithms could deconvolve a blurred satellite image. The simulation environment assumed the key parameters …
A Decline In The Nonthermal X-Ray Emission From Cassiopeia A,
2011
Smithsonian Astrophysical Observatory
A Decline In The Nonthermal X-Ray Emission From Cassiopeia A, Daniel J. Patnaude, Jacco Vink, J. Martin Laming, Robert A. Fesen
Dartmouth Scholarship
We present new Chandra ACIS-S3 observations of Cassiopeia A which, when combined with earlier ACIS-S3 observations, show evidence for a steady ~ 1.5-2%/yr decline in the 4.2-6.0 keV X-ray emission between the years 2000 and 2010. The computed flux from exposure corrected images over the entire remnant showed a 17% decline over the entire remnant and a slightly larger (21%) decline from regions along the remnant's western limb. Spectral fits of the 4.2-6.0 keV emission across the entire remnant, forward shock filaments, and interior filaments indicate the remnant's nonthermal spectral powerlaw index has steepened by about 10%, with interior filaments …
Time-Series Observations Of The High Mass X-Ray Binary 4u 2206+54 To Monitor Light Variation,
2011
Brigham Young University - Provo
Time-Series Observations Of The High Mass X-Ray Binary 4u 2206+54 To Monitor Light Variation, Jessica Lynn Bugno
Theses and Dissertations
The high mass X-ray binary 4U 2206+54 has been a very controversial system due to variability in spectral data as well as photometric data. We, at Brigham Young University, have been observing this system in multiple filters with several telescopes. This thesis presents our methods of observations, reductions, and results. It also compares what we have been detecting to other groups looking at the same target in different wavelengths. Furthermore, this thesis discusses some of the peculiarities of 4U 2206+54 and possible theories to explain these phenomena. Based on our photometric observations for the past three years, we believe the …
Discovery Of Tev Gamma Ray Emission From Tycho's Supernova Remnant,
2011
Department of Physical Sciences, Cork Institute of Technology, Bishopstown, Cork, Ireland
Discovery Of Tev Gamma Ray Emission From Tycho's Supernova Remnant, P. T. Reynolds, Et Al
Physical Sciences Publications
We report the discovery of TeV gamma-ray emission from the Type Ia supernova remnant (SNR) G120.1+1.4, known as Tycho's SNR. Observations performed in the period 2008-2010 with the VERITAS ground-based gamma-ray observatory reveal weak emission coming from the direction of the remnant, compatible with a point source located at 00h25m270, + 64°10'50'' (J2000). The TeV photon spectrum measured by VERITAS can be described with a power law dN/dE = C(E/3.42 TeV)–Γ with Γ = 1.95 ± 0.51stat ± 0.30sys and C = (1.55 ± 0.43stat ± 0.47sys) × 10–14 cm–2 s–1 TeV–1. The integral …
Profiles In Science: Stephen Hawking,
2011
University of Arkansas, Fayetteville
Profiles In Science: Stephen Hawking, Kathleen A. Lehman
University Libraries Faculty Publications and Presentations
While Stephen Hawking’s early academic career lacked focus, the development of motor neuron disease straining against his hopes for a fulfilling life pulled the young scientist’s work together. He has since become the world’s most famous scientist due, in part, to his strong belief that science should be accessible to the general public. Hawking has published frequently for the academic community but has also published for the lay reader. His life has been recorded and examined by several biographers. This paper gives an overview of Hawking’s early life, academic career, his academic and popular publications, as well as a few …
A Distinctive Disk-Jet Coupling In The Seyfert-1 Active Galactic Nucleus Ngc 4051,
2011
University of Michigan
A Distinctive Disk-Jet Coupling In The Seyfert-1 Active Galactic Nucleus Ngc 4051, A. L. King, J. M. Miller, E. M. Cackett, A. C. Fabian, S. Markoff, M. A. Nowak, M. Rupen, K. Gültekin, M. T. Reynolds
Physics and Astronomy Faculty Research Publications
We report on the results of a simultaneous monitoring campaign employing eight Chandra X-ray (0.5-10 keV) and six Very Large Array/Extended Very Large Array (8.4 GHz) radio observations of NGC 4051 over seven months. Evidence for compact jets is observed in the 8.4 GHz radio band; this builds on mounting evidence that jet production may be prevalent even in radio-quiet Seyferts. Assuming comparatively negligible local diffuse emission in the nucleus, the results also demonstrate an inverse correlation of L radio ∝ L -0.72±0.04 X-ray . If the A configuration is excluded in the case where diffuse emission plays a significant …
Spectral Energy Distribution Of Markarian 501: Quiescent State Versus Extreme Outburst,
2011
Cork Institute of Technology
Spectral Energy Distribution Of Markarian 501: Quiescent State Versus Extreme Outburst, P. T. Reynolds, Veritas, Magic
Physical Sciences Publications
The very high energy (VHE; E > 100 GeV) blazar Markarian 501 (Mrk 501) has a well-studied history of extreme spectral variability and is an excellent laboratory for studying the physical processes within the jets of active galactic nuclei. However, there are few detailed multiwavelength studies of Mrk 501 during its quiescent state, due to its low luminosity. A short-term multiwavelength study of Mrk 501 was coordinated in 2009 March, focusing around a multi-day observation with the Suzaku X-ray satellite and including γ-ray data from VERITAS, MAGIC, and the Fermi Gamma-ray Space Telescope with the goal of providing a well-sampled multiwavelength …
An X-Ray Imaging Survey Of Quasar Jets: Testing The Inverse Compton Model,
2011
Massachusetts Institute of Technology
An X-Ray Imaging Survey Of Quasar Jets: Testing The Inverse Compton Model, Herman L. Marshall, Jonathan M. Gelbord, Daniel A. Schwartz, David W. Murphey, James E.J. Lovell, Diana M. Worrall, Mark Birkinshaw, Eric S. Perlman, Leith E.H. Godfrey, David L. Jauncey
Aerospace, Physics, and Space Science Faculty Publications
We present results from continued Chandra X-ray imaging and spectroscopy of a flux-limited sample of flat spectrum radio-emitting quasars with jet-like extended structure. X-rays are detected from 24 of the 39 jets observed so far. We compute the distribution of αrx, the spectral index between the X-ray and radio bands, showing that it is broad, extending at least from 0.8 to 1.2. While there is a general trend that the radio brightest jets are detected most often, it is clear that predicting the X-ray flux from the radio knot flux densities is risky, so a shallow X-ray survey is the …
