Now showing items 1649-1668 of 1674

    • The WEBT campaign on the blazar 3C 279 in 2006 

      Böttcher, Markus; Basu, Shantanu; Joshi, Manasvita; Villata, Massimo; Arai, Akira; Aryan, N.; Asfandiyarov, I. M.; Bach, Uwe; Robertson, Jeff W.; Vennes, Stéphane (2007-12-01)
      The quasar 3C 279 was the target of an extensive multiwavelength monitoring campaign from 2006 January through April. An optical-IR-radio monitoring campaign by the Whole Earth Blazar Telescope (WEBT) collaboration was ...
    • Weighted Composition Operators From Logarithmic Bloch-Type Spaces To Bloch-Type Spaces 

      Stevic, Stevo; Agarwal, Ravi P. (2009-07-03)
      The boundedness and compactness of the weighted composition operators from to Bloch-type spaces are studied here. © 2009 S. Stević and R. P. Agarwal.
    • Where Are the Magnetic White Dwarfs with Detached, Nondegenerate Companions? 

      Liebert, James W.; Wickramsinghe, Dayal T.; Schmidt, Gary D.; Silvestri, Nicole M.; Hawley, Suzanne L.; Szkody, Paula; Ferrario, Lilia; Webbink, Ronald F.; Oswalt, T. D.; Smith, Jonathan Allyn (2005-05)
      The Sloan Digital Sky Survey has already more than doubled the sample of white dwarfs with spectral classi- fications, the subset with detached M dwarf companions, and the subset of magnetic white dwarfs. In the course ...
    • White dwarf cosmochronometry. I. Monte Carlo simulations of proper-motion and magnitude-limited samples using Schmidt's 1/Vmax estimator 

      Wood, Matt A.; Oswalt, T. D. (1998-04-20)
      Observationally, white dwarf stars are a remarkably homogeneous class with a minimum observed Teff ∼ 4000 K. Theoretically, the physics that determines their cooling timescales is relatively more straightforward than that ...
    • White dwarfs in common proper motion binary systems: Mass distribution and kinematics 

      Silvestri, Nicole M.; Oswalt, T. D.; Wood, Matt A.; Smith, Jonathan Allyn; Reid, Iain Neill; Sión, Edward M. (2001-01)
      We present the mass distribution, gravitational redshifts, radial velocities, and space motions of white dwarf stars in common proper motion binary systems. The mass distribution we derive for the 41 DA white dwarfs in ...
    • White dwarfs in globular clusters: Hubble space telescope observations of M4 

      Richer, Harvey B.; Fahlman, Gregory G.; Ibata, Rodrigo A.; Pryor, Carlton; Bell, Roger A.; Bolte, Michael S.; Bond, Howard E.; Harris, William E.; Hesser, James E.; Wood, Matt A. (1997-08-01)
      Using WFPC2 on the Hubble Space Telescope, we have isolated a sample of 258 white dwarfs (WDs) in the Galactic globular cluster M4. Fields at three radial distances from the cluster center were observed, and sizable WD ...
    • The white dwarfs within 20 parsecs of the sun: Kinematics and statistics 

      Sión, Edward M.; Holberg, Jay B.; Oswalt, T. D.; McCook, George P.; Wasatonic, Richard P. (2009-12)
      We present the kinematical properties, distribution of spectroscopic subtypes, and stellar population subcomponents of the white dwarfs within 20 pc of the Sun. We find no convincing evidence of halo white dwarfs in the ...
    • The white dwarfs within 25 pc of the sun: Kinematics and spectroscopic subtypes 

      Sión, Edward M.; Holberg, Jay B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard P.; Myszka, Janine (2014-05-01)
      We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence ...
    • Whole Earth Telescope discovery of a strongly distorted quadrupole pulsation in the largest amplitude rapidly oscillating Ap star 

      Holdsworth, Daniel L.; Kurtz, Donald W.; Saio, Hideyuki; Provençal, Judith L.; Letarte, Bruno; Sefako, Ramotholo R.; Petit, Véronique; Smalley, Barry; Thomsen, H.; Fletcher, C. L. (2018-01-01)
      We present a new analysis of the rapidly oscillating Ap (roAp) star, 2MASS J19400781 - 4420093 (J1940; V = 13.1). The star was discovered using SuperWASP broad-band photometry to have a frequency of 176.39 d-1 (2041.55 ...
    • Whole earth telescope observations of the helium interacting binary PG 1346+082 (CR Bootis) 

      Provençal, Judith L.; Winget, Don Earl; Nather, R. Edward; Robinson, Edward L.; Clemens, J. Christopher; Bradley, Paul A.; Claver, Charles F.; Kleinman, Scot J.; Grauer, Albert D.; Wood, Matt A. (1997-05-01)
      We present our analysis of 240 hr of white-light, high-speed photometry of the dwarf nova-like helium variable PG 1346+082 (CR Boo). We identify two frequencies in the low-state power spectrum, at 679.670 ± 0.004 μHz and ...
    • Whole earth telescope observations of the pulsating subdwarf B Star PG 0014+067 

      Vučković, Maja; Kawaler, Steven D.; O'Toole, Simon J.; Csubry, Zoltán; Baran, Andrzej S.; Zoła, Stanislaw; Moskalik, Paweł A.; Klumpe, Eric W.; Wood, Matt A.; Wilkat, V. (2006-08-01)
      PG 0014+067 is one of the most promising pulsating subdwarf B stars for seismic analysis, as it has a rich pulsation spectrum. The richness of its pulsations, however, poses a fundamental challenge to understanding the ...
    • Whole Earth telescope observations of the ZZ Ceti star HL Tau 76 

      Dolez, Noël; Vauclair, Gérard P.; Kleinman, Scot J.; Chevreton, M.; Fu, Jianning; Solheim, Jan Erik; Pérez, Jaime M González; Wood, Matt A.; Ahrens, Thomas J.; Silvestri, Nicole M. (2006-01)
      This paper analyses the Whole Earth Telescope observations of HL Tau 76, the first discovered pulsating DA white dwarf. The star was observed during two Whole Earth Telescope campaigns. It was a second priority target ...
    • Wide binary systems and the nature of high-velocity white dwarfs 

      Silvestri, Nicole M.; Oswalt, T. D.; Hawley, Suzanne L. (2002-08)
      We present measured radial velocities and complete space motions for 116 white dwarf stars with M dwarf companions. Thirteen pairs have " halo-like " velocities. According to a recent study by Oppenheimer et al., all these ...
    • Work-of-indentation as a means to characterize indenter geometry and load-displacement response of a material 

      Jha, Kaushal K.; Zhang, Shuo; Suksawang, Nakin; Wang, Ton-Lo; Agarwal, Arvind (2013-09-23)
      Normalized indentation works, referred to as the total and elastic energy constants, have been shown to be effective in the representation and analysis of experimental load-displacement data. However, their physical ...
    • X-ray bursts associated with leader steps in cloud-to-ground lightning 

      Dwyer, Joseph R.; Rassoul, Hamid K.; Dayeh, M. A.; Caraway, Lee; Chrest, A.; Wright, Brian F.; Kozak, E.; Jerauld, J.; Uman, Martin A.; Rakov, V. (2005-01-04)
      X-ray and electric field measurements were made during five nearby negative natural lightning strikes in north central Florida during the summer of 2004. The observed X-ray emission typically was detected ∼1 ms before the ...
    • X-ray bursts produced by laboratory sparks in air 

      Dwyer, Joseph R.; Rassoul, Hamid K.; Saleh, Ziad H.; Uman, Martin A.; Jerauld, J.; Plumer, J. Anderson (2005-10-22)
      X-ray observations were made during fourteen 1.5 to 2.0 m high-voltage discharges in air produced by a 1.5 MV Marx circuit. All 14 discharges generated x-rays in the ∼30 to 150 keV range. The x-rays, which arrived in ...
    • X-ray emission from magnetic massive stars 

      Nazé, Yaël; Petit, Véronique; Rinbrand, Melanie; Cohen, David H.; Owocki, Stanley P.; Ud-Doula, Asif; Wade, Gregg A. (2014-10-30)
      Magnetically confined winds of early-type stars are expected to be sources of bright and hard X-rays. To clarify the systematics of the observed X-ray properties, we have analyzed a large series of Chandra and XMM-Newton ...
    • An X-ray imaging survey of quasar jets: Testing the inverse Compton model 

      Marshall, Herman L.; Gelbord, Jonathan M.; Schwartz, Daniel A.; Murphey, David W.; Lovell, James E. J.; Worrall, Diana M.; Birkinshaw, Mark; Perlman, Eric S.; Godfrey, Leith E. H.; Jauncey, David L. (2011-03-01)
      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 ...
    • An X-Ray Imaging Survey of Quasar Jets: The Complete Survey 

      Marshall, Herman L.; Gelbord, Jonathan M.; Worrall, Diana M.; Birkinshaw, Mark; Schwartz, Daniel A.; Jauncey, David L.; Griffiths, G.; Murphy, David W.; Lovell, James E.J.; Perlman, Eric S. (2018-03-20)
      We present Chandra X-ray imaging of a flux-limited sample of flat spectrum radio-emitting quasars with jet-like structure. X-rays are detected from 59% of 56 jets. No counter-jets were detected. The core spectra are fitted ...
    • X-ray nuclear activity in S4G barred galaxies: no link between bar strength and co-occurrent supermassive black hole fueling 

      Cisternas, Mauricio; Gadotti, Dimitri A.; Knapen, Johan H.; Kim, Taehyun; Díaz-García, Simón; Laurikainen, Eija; Salo, Heikki; González-Martín, Omaira; Ho, Luis C.; Mizusawa, Trisha (2013-10-10)
      Stellar bars can lead to gas inflow toward the center of a galaxy and stimulate nuclear star formation. However, there is no compelling evidence on whether they also feed a central supermassive black hole: by measuring the ...