Search Publications
FUSE and HST STIS Far-Ultraviolet Observations of AM Herculis in an Extended Low State
Hubeny, Ivan; Gänsicke, Boris T.; Long, Knox S. +1 more
We have obtained FUSE and HST STIS time-resolved spectroscopy of the Polar AM Herculis during a deep low state. The spectra are entirely dominated by the emission of the white dwarf. Both the far-ultraviolet (FUV) flux and the spectral shape vary substantially over the orbital period, with maximum flux occurring at the same phase as during the hig…
Evidence for a Supernova Associated with the X-Ray Flash 020903
Covino, S.; Becker, A. C.; Filippenko, A. V. +24 more
We present ground-based and Hubble Space Telescope optical observations of the X-ray flash (XRF) 020903, covering 300 days. The afterglow showed a very rapid rise in the first day, followed by a relatively slow decay in the next few days. There was a clear bump in the light curve after ~25 days, accompanied by a drastic change in the spectral ener…
Rings and Bent Chain Galaxies in the GEMS and GOODS Fields
Elmegreen, Bruce G.; Elmegreen, Debra Meloy
Twenty-four galaxies with rings or partial rings were studied in the GEMS and GOODS fields out to z~1.4. Most resemble local collisional ring galaxies in morphology, size, and clumpy star formation. Clump ages range from 108 to 109 yr, and clump masses go up to several × 108 Msolar, based on color evolut…
Cyclotron Resonance Energies at a Low X-Ray Luminosity: A0535+262 Observed with Suzaku
Mukai, K.; Yonetoku, D.; Mihara, T. +28 more
The binary X-ray pulsar A0535+262 was observed with the Suzaku X-ray observatory on 2005 September 14 for a net exposure of 22 ks. The source was in the declining phase of a minor outburst, exhibiting 3-50 keV luminosity of ~3.7×1035 ergs s-1 at an assumed distance of 2 kpc. In spite of the very low source intensity (about 30…
On the Feedback from Super Stellar Clusters. I. The Structure of Giant H II Regions and H II Galaxies
Tenorio-Tagle, Guillermo; Muñoz-Tuñón, Casiana; Pérez, Enrique +2 more
We review the structural properties of giant extragalactic H II regions and H II galaxies based on two-dimensional hydrodynamic calculations and propose an evolutionary sequence that accounts for their observed detailed structure. The model assumes a massive and young stellar cluster surrounded by a large collection of clouds. These are thus expos…
Statistical Analysis of Reconnection Inflows in Solar Flares Observed with SOHO EIT
Shibata, Kazunari; Narukage, Noriyuki
We report observations of reconnection inflows in extreme ultraviolet (EUV) Fe XII λ195 images with the Extreme Ultraviolet Imaging Telescope (EIT) on board the Solar and Heliospheric Observatory (SOHO). Yokoyama and colleagues reported the first example observed on 1999 March 18. We survey the EIT data from 1996 to 2000 and find six new inflow ev…
Binary and Multiple O-Type Stars in the Cassiopeia OB6 Association
Gies, Douglas R.; Bagnuolo, William G., Jr.; McSwain, M. Virginia +3 more
We present the results of time-resolved spectroscopy of 13 O-type stars in the Cas OB6 stellar association. We conducted a survey for radial velocity variability in search of binary systems, which are expected to be plentiful in young OB associations. Here we report the discovery of two new single-lined binaries, and we present new orbital element…
Type II Quasars from the Sloan Digital Sky Survey. IV. Chandra and XMM-Newton Observations Reveal Heavily Absorbed Sources
Strauss, Michael A.; Schneider, Donald P.; Heckman, Timothy M. +4 more
We are carrying out sensitive X-ray observations with Chandra and XMM-Newton of type II quasars selected from the Sloan Digital Sky Survey based on their optical emission line properties. In this paper we present the first results of our program. We present observations of four objects at redshifts 0.4<z<0.8, and an analysis of the archival …
Extinction Columns and Intrinsic X-Ray Spectra of the Anomalous X-Ray Pulsars
Durant, Martin; van Kerkwijk, Marten H.
The X-ray spectra of anomalous X-ray pulsars have long been fit by smooth, empirical models such as the sum of a blackbody plus a power law. These reproduce the ~0.5-10 keV range well, but fail at lower and higher energies, grossly overpredicting the optical and underpredicting the hard X-ray emission. A poorly constrained source of uncertainty in…
The Sunyaev-Zel'dovich Effect in a Sample of 31 Clusters: A Comparison between the X-Ray Predicted and WMAP Observed Cosmic Microwave Background Temperature Decrement
Zhang, Shuang-Nan; Lieu, Richard; Mittaz, Jonathan P. D.
The WMAP Q-, V-, and W-band radial profiles of temperature deviation of the cosmic microwave background (CMB) were constructed for a sample of 31 randomly selected nearby clusters of galaxies in directions of Galactic latitude b>30deg. The profiles were compared in detail with the expected CMB Sunyaev-Zel'dovich effect (SZE) caused b…