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Articles 6301 - 6330 of 8865

Full-Text Articles in Astrophysics and Astronomy

Multisite Photometry Of The Pulsating Herbig Ae Star V346 Ori, S. Bernabei, Terry D. Oswalt, V. Ripepi, A. Ruoppo, Et Al. Apr 2009

Multisite Photometry Of The Pulsating Herbig Ae Star V346 Ori, S. Bernabei, Terry D. Oswalt, V. Ripepi, A. Ruoppo, Et Al.

Publications

The study of pulsation in Pre--Main--Sequence intermediate-mass stars represents an important tool for deriving information on fundamental stellar parameters and internal structure, as well as for testing current theoretical models. Interest in this class of variable stars has significantly increased during the last decade and about 30 members are presently known in the literature. AIMS: We have constructed the frequency spectrum of the oscillations in V346 Ori. We apply asteroseismic tools to these data to estimate the intrinsic parameters (mass, luminosity, effective temperature) of V346 Ori and to obtain information on its internal structure. METHODS: CCD time series photometry in …

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A Search For Multi-Planet Systems Using The Hobby–Eberly Telescope, Robert A. Wittenmyer, Michael Endl, William D. Cochran, Harold F. Levison, Gregory W. Henry Apr 2009

A Search For Multi-Planet Systems Using The Hobby–Eberly Telescope, Robert A. Wittenmyer, Michael Endl, William D. Cochran, Harold F. Levison, Gregory W. Henry

Information Systems and Engineering Management Research Publications

Extrasolar multiple-planet systems provide valuable opportunities for testing theories of planet formation and evolution. The architectures of the known multiple-planet systems demonstrate a fascinating level of diversity, which motivates the search for additional examples of such systems in order to better constrain their formation and dynamical histories. Here we describe a comprehensive investigation of 22 planetary systems in an effort to answer three questions: (1) are there additional planets? (2) where could additional planets reside in stable orbits? and (3) what limits can these observations place on such objects? We find no evidence for additional bodies in any of these …

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The Nasa-Uc Eta-Earth Program. I. A Super-Earth Orbiting Hd 7924, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Matthew J. Giguere, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai Piskunov Apr 2009

The Nasa-Uc Eta-Earth Program. I. A Super-Earth Orbiting Hd 7924, Andrew W. Howard, John Asher Johnson, Geoffrey W. Marcy, Debra A. Fischer, Jason T. Wright, Gregory W. Henry, Matthew J. Giguere, Howard Isaacson, Jeff A. Valenti, Jay Anderson, Nikolai Piskunov

Information Systems and Engineering Management Research Publications

We report the discovery of the first low-mass planet to emerge from the NASA-UC Eta-Earth Program, a super-Earth orbiting the K0 dwarf HD 7924. Keplerian modeling of precise Doppler radial velocities reveals a planet with minimum mass MPsin i = 9.26 M⊕ in a P = 5.398 d orbit. Based on Keck-HIRES measurements from 2001 to 2008, the planet is robustly detected with an estimated false alarm probability of less than 0.001. Photometric observations using the Automated Photometric Telescopes at Fairborn Observatory show that HD 7924 is photometrically constant over the radial velocity period to 0.19 mmag, supporting the existence …

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Hr 8257: A Three-Dimensional Orbit And Basic Properties, Francis C. Fekel, Andrew F. Boden, Jocelyn Tomkin, Guillermo Torres Apr 2009

Hr 8257: A Three-Dimensional Orbit And Basic Properties, Francis C. Fekel, Andrew F. Boden, Jocelyn Tomkin, Guillermo Torres

Information Systems and Engineering Management Research Publications

We have used interferometric and spectroscopic observations of HR 8257 to determine a three-dimensional orbit of the system. The orbit has a period of 12.21345 days and an eccentricity of 0.2895. The masses of the F0 and F2 dwarf components are 1.56 and 1.38 M☉, respectively, with fractional errors of 1.4%. Our orbital parallax of 13.632 ± 0.095 mas, corresponding to a distance of 73.4 ± 0.6 pc, differs from the Hipparcos result by just 2% and has a significantly smaller uncertainty. From our spectroscopic observations and spectral energy distribution modeling we determine the component effective temperatures and luminosities to …

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Distance To The Sagittarius Dwarf Galaxy Using Macho Project Rr Lyrae Stars, Andrea Kunder, Brian Chaboyer Apr 2009

Distance To The Sagittarius Dwarf Galaxy Using Macho Project Rr Lyrae Stars, Andrea Kunder, Brian Chaboyer

Dartmouth Scholarship

We derive the distance to the northern extension of the Sagittarius (Sgr) dwarf spheroidal galaxy from 203 Sgr RR0 Lyrae stars found in the MACHO database. Their distances are determined differentially with respect to 288 Galactic bulge RR0 Lyrae stars also found in the MACHO data. We find a distance modulus difference of 2.41 mag at l = 5◦ and b =− 8◦ and that the extension of the Sgr galaxy toward the galactic plane is inclined toward us. Assuming R GC = 8 kpc, this implies the distance to these stars is (m − M) 0 = …

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Spectroscopic Measurements Of Temperature And Plasma Impurity Concentration During Magnetic Reconnection At The Swarthmore Spheromak Experiment, Vernon Hampden Chaplin , '07, Michael R. Brown, David H. Cohen, T. Gray, C. D. Cothran Apr 2009

Spectroscopic Measurements Of Temperature And Plasma Impurity Concentration During Magnetic Reconnection At The Swarthmore Spheromak Experiment, Vernon Hampden Chaplin , '07, Michael R. Brown, David H. Cohen, T. Gray, C. D. Cothran

Physics & Astronomy Faculty Works

Electron temperature measurements during counterhelicity spheromak merging studies at the Swarthmore Spheromak Experiment (SSX) [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] are presented. VUV monochromator measurements of impurity emission lines are compared with model spectra produced by the non-LTE excitation kinematics code PRISMSPECT [J. J. MacFarlane et al., in Proceedings of the Third Conference on Inertial Fusion Science and Applications (2004)] to yield the electron temperature in the plasma with 1 mu s time resolution. Average T(e) is seen to increase from 12 to 19 eV during spheromak merging. Average C III ion temperature, measured with a new ion …

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Suzaku Observations Of The Black Hole H1743-322 In Outburst, J. L. Blum, J. M. Miller, E. Cackett, K. Yamaoka, H. Takahashi, J. Raymond, C. S. Reynolds, A. C. Fabian Apr 2009

Suzaku Observations Of The Black Hole H1743-322 In Outburst, J. L. Blum, J. M. Miller, E. Cackett, K. Yamaoka, H. Takahashi, J. Raymond, C. S. Reynolds, A. C. Fabian

Physics and Astronomy Faculty Research Publications

We observed the Galactic black hole candidate H1743-322 with Suzaku for approximately 32 ks, while the source was in a low/hard state during its 2008 outburst. We collected and analyzed the data with the HXD/PIN, HXD/GSO, and XIS cameras spanning the energy range 0.7-200 keV. Fits to the spectra with simple models fail to detect narrow Fe XXV and Fe XXVI absorption lines, with 90% confidence upper limits of 3.5 and 2.5 eV on the equivalent width, respectively. These limits are commensurate with those in the very high state, but are well below the equivalent widths of lines detected in …

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Stellar Population Models And Individual Element Abundances. Ii. Stellar Spectra And Integrated Light Models, Hyun-Chul Lee, Guy Worthey, Aaron Dotter, Brian Chaboyer Apr 2009

Stellar Population Models And Individual Element Abundances. Ii. Stellar Spectra And Integrated Light Models, Hyun-Chul Lee, Guy Worthey, Aaron Dotter, Brian Chaboyer

Dartmouth Scholarship

The first paper in this series explored the effects of altering the chemical mixture of the stellar population on an element-by-element basis on stellar evolutionary tracks and isochrones to the end of the red giant branch. This paper extends the discussion by incorporating the fully consistent synthetic stellar spectra with those isochrone models in predicting integrated colors, Lick indices, and synthetic spectra. Older populations display element ratio effects in their spectra at higher amplitude than younger populations. In addition, spectral effects in the photospheres of stars tend to dominate over effects from isochrone temperatures and lifetimes, but, further, the isochrone-based …

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Impact Of Spherical Probe Scattering On Estimation Of Acoustic Vector Quantities. (A), Curtis P. Wiederhold, Kent L. Gee, Derek C. Thomas, Scott D. Sommerfeldt, Jonathan D. Blotter Apr 2009

Impact Of Spherical Probe Scattering On Estimation Of Acoustic Vector Quantities. (A), Curtis P. Wiederhold, Kent L. Gee, Derek C. Thomas, Scott D. Sommerfeldt, Jonathan D. Blotter

Faculty Publications

Multimicrophone probes are often used to measure energy-based acoustical quantities. In some cases, these probes consist of microphones mounted on the surface of a sphere, which, due to the high level of symmetry, permits scattering effects to be better characterized. Scattering of a plane wave incident on a rigid sphere has been modeled to observe how particle velocity and intensity calculations are affected by the presence of the sphere. These effects have been investigated for the traditional "finite-difference" method and a recently developed "wave vector" estimation method. In the computer model, 3-D surface plots were made showing the calculated error …

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The Acs Survey Of Galactic Globular Clusters. Vii. Relative Ages, Antonio Marín-Franch, Antonio Aparicio, Giampaolo Piotto, Alfred Rosenberg, Brian Chaboyer Apr 2009

The Acs Survey Of Galactic Globular Clusters. Vii. Relative Ages, Antonio Marín-Franch, Antonio Aparicio, Giampaolo Piotto, Alfred Rosenberg, Brian Chaboyer

Dartmouth Scholarship

The ACS Survey of Galactic globular clusters is a Hubble Space Telescope Treasury program designed to provide a new large, deep, and homogeneous photometric database. Based on observations from this program, we have measured precise relative ages for a sample of 64 Galactic globular clusters by comparing the relative position of the clusters' main-sequence (MS) turnoffs, using MS fitting to cross-compare clusters within the sample. This method provides relative ages to a formal precision of 2%-7%. We demonstrate that the calculated relative ages are independent of the choice of theoretical model. We find that the Galactic globular cluster sample can …

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Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen Apr 2009

Spectrophotometrically Identified Stars In The Pears-N And Pears-S Fields., N. Pirzkal, A. J. Burgasser, S. Malhotra, Benne W. Holwerda, K. C. Sahu, J. E. Rhoads, C. Xu, J. J. Bochanski, J. R. Walsh, R. A. Windhorst, N. P. Hathi, S. H. Cohen

Faculty and Staff Scholarship

Deep ACS slitless grism observations and identification of stellar sources are presented within the Great Observatories Origins Deep Survey North and South fields which were obtained in the Probing Evolution And Reionization Spectroscopically (PEARS) program. It is demonstrated that even low-resolution spectra can be a very powerful means of identifying stars in the field, especially low-mass stars with stellar types M0 and later. The PEARS fields lay within the larger GOODS fields, and we used new, deeper images to further refine the selection of stars in the PEARS field, down to a magnitude of z850 = 25 using a newly …

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Tempo2: A New Pulsar Timing Package - Iii. Gravitational Wave Simulation, G. Hobbs, F. Jenet, K. J. Lee, J. P.W. Verbiest, D. Yardley, R. Manchester, A. Lommen, W. Coles, R. Edwards, C. Shettigara Apr 2009

Tempo2: A New Pulsar Timing Package - Iii. Gravitational Wave Simulation, G. Hobbs, F. Jenet, K. J. Lee, J. P.W. Verbiest, D. Yardley, R. Manchester, A. Lommen, W. Coles, R. Edwards, C. Shettigara

Physics & Astronomy Faculty Publications

Analysis of pulsar timing data sets may provide the first direct detection of gravitational waves. This paper, the third in a series describing the mathematical framework implemented into the TEMPO2 pulsar timing package, reports on using TEMPO2 to simulate the timing residuals induced by gravitational waves. The TEMPO2 simulations can be used to provide upper bounds on the amplitude of an isotropic, stochastic, gravitational wave background in our Galaxy and to determine the sensitivity of a given pulsar timing experiment to individual, supermassive, binary black hole systems. © 2009 The Authors. Journal compilation © 2009 RAS.

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Detecting A Stochastic Gravitational-Wave Background: The Overlap Reduction Function, Lee Samuel Finn, Shane L. Larson, Joseph D. Romano Mar 2009

Detecting A Stochastic Gravitational-Wave Background: The Overlap Reduction Function, Lee Samuel Finn, Shane L. Larson, Joseph D. Romano

Physics & Astronomy Faculty Publications

Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross correlation of the response of two or more independent detectors. The cross correlation involves a frequency-dependent factor—the so-called overlap reduction function or HellingsDowns curve—that depends on the relative geometry of each detector pair, i.e., the detector separations and the relative orientation of their antenna patterns (beams). An incorrect formulation of this geometrical factor has appeared in the literature, leading to incorrect conclusions regarding the sensitivity of proposed detectors to a stochastic gravitational-wave background. To rectify these errors and as a reference for future work we …

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The Nature Of The Light Variability Of The Silicon Star Hr 7224, Jiří Krtička, Zdeněk Mikulášek, Gregory W. Henry, Juraj Zverko, Jozef Žižňovský, Jan Skalický, Pavel Zvěřina Mar 2009

The Nature Of The Light Variability Of The Silicon Star Hr 7224, Jiří Krtička, Zdeněk Mikulášek, Gregory W. Henry, Juraj Zverko, Jozef Žižňovský, Jan Skalický, Pavel Zvěřina

Information Systems and Engineering Management Research Publications

Context. Although photometric variations of chemically peculiar (CP) stars are frequently used to determine their rotational periods, the detailed mechanism of their light variability remains poorly understood.
Aims. We simulate the light variability of the star HR 7224 using the observed surface distribution of silicon and iron.
Methods. We used the TLUSTY model atmospheres calculated for the appropriate silicon and iron abundances to obtain the emergent flux and to predict the rotationally modulated light curve of the star. We also obtained additional photometric measurements and employed our own regression procedure to derive a more precise estimate of the light elements. …

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New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich Mar 2009

New Neighbors: Parallaxes Of 18 Nearby Stars Selected From The Lspm-North Catalog, Sébastien Lépine, John R. Thorstensen, Michael M. Shara, R. Michael Rich

Dartmouth Scholarship

We present astrometric parallaxes for 18 suspected nearby stars selected from the LSPM-north proper motion catalog. 16 objects are confirmed to be main-sequence M dwarfs within 16 pc of the Sun, including three stars (LSPM J0011+5908, LSPM J0330+5413, and LSPM J0510+2714) which lie just within the 10 pc horizon. Two other targets (LSPM J1817+1328, LSPM J2325+1403) are confirmed to be nearby white dwarfs at distances of 14 and 22 pc, respectively. One of our targets, the common proper motion pair LSPM J0405+7116E + LSPM J0405+7116W, is revealed to be a triple system, with the western component resolved into a pair …

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Extreme Physics Where Small And Big Things Meet, Young-Kee Kim Mar 2009

Extreme Physics Where Small And Big Things Meet, Young-Kee Kim

IMSA Great Minds Program ®

The profound discovery of Einstein a century ago, that particles can both be made from energy and disappear back into energy, inspires the experiments that provide our knowledge of the smallest building blocks of matter and the interactions between them. Experiments, done at enormous accelerators, have led to a consistent theory of the origins of our world up to a certain point. However, at an energy scale not far above what we can attain at existing accelerators, this picture is predicted to break down. Moreover, the theory of the very small is intimately connected to cosmology -- the ultimate cause …

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Ringworld: Travellers' Tales From Saturn, Shane L. Larson Mar 2009

Ringworld: Travellers' Tales From Saturn, Shane L. Larson

Public Talks

No abstract provided.

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Hearing Voices In The Dark: Probing The Gravitational Wave Cosmos With Lisa, Shane L. Larson Mar 2009

Hearing Voices In The Dark: Probing The Gravitational Wave Cosmos With Lisa, Shane L. Larson

Colloquia and Seminars

No abstract provided.

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All-Sky Ligo Search For Periodic Gravitational Waves In The Early Fifth-Science-Run Data, B. P. Abbott, R. Abbott, R. Adhikari, P. Ajith, B. Allen, G. Allen, R. S. Amin, S. B. Anderson, W. G. Anderson, M. A. Arain, M. Araya, H. Armandula, P. Armor, Y. Aso, S. Aston, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, S. Ballmer, H. Bantilan, B. C. Barish, C. Barker, D. Barker, B. Barr, P. Barriga, L. Barsotti, M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, Tiffany Z. Summerscales Mar 2009

All-Sky Ligo Search For Periodic Gravitational Waves In The Early Fifth-Science-Run Data, B. P. Abbott, R. Abbott, R. Adhikari, P. Ajith, B. Allen, G. Allen, R. S. Amin, S. B. Anderson, W. G. Anderson, M. A. Arain, M. Araya, H. Armandula, P. Armor, Y. Aso, S. Aston, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, S. Ballmer, H. Bantilan, B. C. Barish, C. Barker, D. Barker, B. Barr, P. Barriga, L. Barsotti, M. A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, Tiffany Z. Summerscales

Faculty Publications

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100Hz and with the frequency's time derivative in the range -5×10-9-0Hzs-1. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10-24 are obtained over a 200-Hz band, and the sensitivity …

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Photometric Calibrations For 21st Century Science, Stephen M. Kent, Terry D. Oswalt, Mary Elizabeth Kaiser, Et Al. Mar 2009

Photometric Calibrations For 21st Century Science, Stephen M. Kent, Terry D. Oswalt, Mary Elizabeth Kaiser, Et Al.

Publications

The answers to fundamental science questions in astrophysics, ranging from the history of the expansion of the universe to the sizes of nearby stars, hinge on our ability to make precise measurements of diverse astronomical objects. As our knowledge of the underlying physics of objects improves along with advances in detectors and instrumentation, the limits on our capability to extract science from measurements is set, not by our lack of understanding of the nature of these objects, but rather by the most mundane of all issues: the precision with which we can calibrate observations in physical units. We stress the …

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Resonant Microwave Cavity For 8.5-12 Ghz Optically Detected Electron Spin Resonance With Simultaneous Nuclear Magnetic Resonance, John S. Colton, L. R. Wienkes Mar 2009

Resonant Microwave Cavity For 8.5-12 Ghz Optically Detected Electron Spin Resonance With Simultaneous Nuclear Magnetic Resonance, John S. Colton, L. R. Wienkes

Faculty Publications

We present a newly developed microwave resonant cavity for use in optically detected magnetic resonance (ODMR) experiments. The cylindrical quasi-TE 011 mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency between 8.5 and 12 GHz. The cavity uses cylinders of high dielectric material, so-called "dielectric resonators," in a double-stacked configuration to determine the resonant frequency. Wires in a pseudo-Helmholtz configuration are incorporated into the cavity to provide frequencies for simultaneous nuclear magnetic resonance (NMR). The system was tested by measuring cavity absorption …

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Grb 080913 At Redshift 6.7, J. Greiner, T. Krühler, J. P. U. Fynbo, A. Rossi, R. Schwarz, S. Klose, S. Savaglio, N. R. Tanvir, S. Mcbreen, T Totani, B B. Zhang, X F. Wu, D Watson, S D. Barthelmy, A P. Beardmore, P Ferrero, N Gehrels, D A. Kann, N Kawai, A Küpcü Yoldaş, P Mészáros, B Milvang-Jensen, S R. Oates, D Pierini, P Schady, K Toma, P M. Vreeswijk, A Yoldas, B Zhang, P Afonso, K Aoki, D N. Burrows, C Clemens, R Filgas, Z Haiman, Dieter H. Hartmann Mar 2009

Grb 080913 At Redshift 6.7, J. Greiner, T. Krühler, J. P. U. Fynbo, A. Rossi, R. Schwarz, S. Klose, S. Savaglio, N. R. Tanvir, S. Mcbreen, T Totani, B B. Zhang, X F. Wu, D Watson, S D. Barthelmy, A P. Beardmore, P Ferrero, N Gehrels, D A. Kann, N Kawai, A Küpcü Yoldaş, P Mészáros, B Milvang-Jensen, S R. Oates, D Pierini, P Schady, K Toma, P M. Vreeswijk, A Yoldas, B Zhang, P Afonso, K Aoki, D N. Burrows, C Clemens, R Filgas, Z Haiman, Dieter H. Hartmann

Publications

We report on the detection by Swift of GRB 080913, and subsequent optical/near-infrared follow-up observations by GROND, which led to the discovery of its optical/NIR afterglow and the recognition of its high-z nature via the detection of a spectral break between the i and z bands. Spectroscopy obtained at the ESO-VLT revealed a continuum extending down to λ = 9400 Å, and zero flux for 7500 Å<λ< 9400 Å, which we interpret as the onset of a Gunn–Peterson trough at z = 6.695± 0.025 (95.5% confidence level), making GRB 080913 the highest-redshift gamma-ray burst (GRB) to date, and more distant than the highest-redshift QSO. We note that many redshift indicators that are based on promptly available burst or afterglow properties have failed for GRB 080913. We report on our follow-up campaign and compare the properties of GRB 080913 with bursts at lower redshift. In particular, since the afterglow of this burst is fainter than typical for GRBs, we show that 2 m class telescopes can identify most high-redshift GRBs.

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Composition And Spectral Properties Of The 1 Au Quiet-Time Superthermal Ion Population During Solar Cycle 23, M. A. Dayeh, M. I. Desai, Joseph R. Dwyer, Hamid K. Rassoul, G. M. Mason, J. E. Mazur Mar 2009

Composition And Spectral Properties Of The 1 Au Quiet-Time Superthermal Ion Population During Solar Cycle 23, M. A. Dayeh, M. I. Desai, Joseph R. Dwyer, Hamid K. Rassoul, G. M. Mason, J. E. Mazur

Aerospace, Physics, and Space Science Faculty Publications

We have surveyed the spectral and compositional properties of suprathermal heavy ions during quiet times from 1995 January 1 to 2007 December 31 using Wind/Energetic Particles: Anisotropy, Composition, and Transport/SupraThermal-through-Energetic Particle Telescope and Advanced Composition Explorer/Ultra-low Energy Isotope Spectrometer at energies between 0.04 and 2.56 MeV nucleon−1. We find the following. (1) Quiet-time Fe/O and C/O abundances are correlated with solar cycle activity, reflecting corresponding values measured in solar energetic particle and interplanetary (IP) shock events during solar maximum, and those measured in the solar wind and corotating interaction regions (CIRs) during solar minimum conditions. (2) The 3He/4He ratio lies …

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Pulsar Timing And Spacetime Curvature, Teviet Creighton, Fredrick A. Jenet, Richard H. Price Mar 2009

Pulsar Timing And Spacetime Curvature, Teviet Creighton, Fredrick A. Jenet, Richard H. Price

Physics & Astronomy Faculty Publications

We analyze the effect of weak field gravitational waves on the timing of pulsars, with particular attention to gauge invariance, that is, to the effects that are independent of the choice of coordinates. We find (1) the Doppler shift cannot be separated into gauge invariant gravitational wave and kinetic contributions; (2) a gauge invariant separation can be made for the time derivative of the Doppler shift in which the gravitational wave contribution is directly related to the Riemann tensor, and the kinetic contribution is that for special relativity; (3) the gaugedependent effects in the Doppler shift play no role in …

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New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. Iii. Hd 82191, Ω Draconis, And 108 Herculis, Francis C. Fekel, Jocelyn Tomkin, Michael H. Williamson Mar 2009

New Precision Orbits Of Bright Double-Lined Spectroscopic Binaries. Iii. Hd 82191, Ω Draconis, And 108 Herculis, Francis C. Fekel, Jocelyn Tomkin, Michael H. Williamson

Information Systems and Engineering Management Research Publications

We have determined improved spectroscopic orbits for three double-lined binaries, HD 82191 (Am), ω Dra (F5 V), and 108 Her (Am), using radial velocities from the 2.1 m telescope at McDonald Observatory, the coudé feed telescope at Kitt Peak National Observatory, and 2 m telescope at Fairborn Observatory. The orbital periods range from 5.28 to 9.01 days, and all three systems have circular orbits. The new orbital dimensions (a1 sin i and a2 sin i) and minimum masses (m1 sin3 i and m2 sin3 i) have accuracies of 0.2% or better. Our improved results confirm the large minimum masses of …

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Chandra Observations Of Nuclear X-Ray Emission From Low Surface Brightness Galaxies, Stacy S. Mcgaugh Mar 2009

Chandra Observations Of Nuclear X-Ray Emission From Low Surface Brightness Galaxies, Stacy S. Mcgaugh

Faculty Scholarship

We present Chandra detections of X-ray emission from the active galactic nuclei (AGN) in two giant low surface brightness (LSB) galaxies, UGC 2936 and UGC 1455. Their X-ray luminosities are 1.8 × 1042 ergs s -1 and 1.1 × 1040 ergs s-1 respectively. Of the two galaxies, UGC 2936 is radio loud. Together with another LSB galaxy UGC 6614 (XMM-Newton archival data) both appear to lie above the X-ray-radio fundamental plane, and their AGN have black hole masses that are low compared to similar galaxies lying on the correlation. However, the bulges in these galaxies are well developed, and we …

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Quest For Our Origins, Scott Gaudi '91 Mar 2009

Quest For Our Origins, Scott Gaudi '91

Special Lectures

Dr. Scott Gaudi earned his B.S. from Michigan State University, and his M.S. and Ph.D. from the Ohio State University. He was a Hubble Fellow at the Institute for Advanced Study, and a Menzel Fellow at the Harvard-Smithsonian Center for Astrophysics, before joining the faculty in the Department of Astronomy at the Ohio State University in 2006. He was named one of "20 Scientists to Watch in 20 Years" by Discover Magazine in 2000, was named one of Astronomy Magazine's "10 Rising Stars of Astronomy" in 2008, and was recently awarded the Helen B. Warner Prize for "significant contribution to …

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The Transit Light Curve Project. X. A Christmas Transit Of Hd 17156b, Joshua N. Winn, Matthew J. Holman, Gregory W. Henry, Guillermo Torres, Debra A. Fischer, John Asher Johnson, Geoffrey W. Marcy, Avi Shporer, Tsevi Mazeh Mar 2009

The Transit Light Curve Project. X. A Christmas Transit Of Hd 17156b, Joshua N. Winn, Matthew J. Holman, Gregory W. Henry, Guillermo Torres, Debra A. Fischer, John Asher Johnson, Geoffrey W. Marcy, Avi Shporer, Tsevi Mazeh

Information Systems and Engineering Management Research Publications

Photometry is presented of the 2007 December 25 transit of HD 17156b, which has the longest orbital period and highest orbital eccentricity of all the known transiting exoplanets. New measurements of the stellar radial velocity are also presented. All the data are combined and integrated with stellar-evolutionary modeling to derive refined system parameters. The planet's mass and radius are found to be 3.212+0.069−0.082 MJup and 1.023+0.070−0.055 RJup. The corresponding stellar properties are 1.263+0.035−0.047 M☉ and 1.446+0.099−0.067 R☉. The planet is smaller by 1σ than a theoretical solar-composition gas giant with the same mass and equilibrium temperature, a possible indication of …

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Broad Relativistic Iron Emission Line Observed In Sax J1808.4-3658, E. M. Cackett, D. Altamirano, A. Patruno, J. M. Miller, M. Reynolds, M. Linares, R. Wijnands Mar 2009

Broad Relativistic Iron Emission Line Observed In Sax J1808.4-3658, E. M. Cackett, D. Altamirano, A. Patruno, J. M. Miller, M. Reynolds, M. Linares, R. Wijnands

Physics and Astronomy Faculty Research Publications

During the 2008 September-October outburst of the accreting millisecond pulsar SAX J1808.4-3658, the source was observed by both Suzaku and XMM-Newton approximately 1 day apart. Spectral analysis reveals a broad relativistic Fe Kα emission line which is present in both data sets, as has recently been reported for other neutron star low-mass X-ray binaries. The properties of the Fe K line observed during each observation are very similar. From modeling the Fe line, we determine the inner accretion disk radius to be 13.2 ± 2.5 GM c-2. The inner disk radius measured from the Fe K line suggests …

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Blue-Shifted Emission In Cdte/Znse Heterostructured Nanocrystals, Nishshanka N. Hewa-Kasakarage, Nilanka P. Gurusinghe, Mikhail Zamkov Mar 2009

Blue-Shifted Emission In Cdte/Znse Heterostructured Nanocrystals, Nishshanka N. Hewa-Kasakarage, Nilanka P. Gurusinghe, Mikhail Zamkov

Physics and Astronomy Faculty Publications

Properties of colloidal heterostructured nanocrystals are largely determined by the spatial distribution of photogenerated carriers across the junction of semiconductor materials that form the heterostructure. The two known types of carrier distributions are identified based on whether both carriers reside within the same (type I) or opposite (type II) sides of the heterojunction. Here we demonstrate the existence of another type of spatial carrier distribution in heteronanocrystals, which corresponds to the localization of both charges along the material junction. Such localization. pattern was realized in novel CdTe/ZnSe heteronanocrystals, where the expected type I infrared emission was dominated by more intense …

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