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When Is a Bulge Not a Bulge? Inner Disks Masquerading as Bulges in NGC 2787 and NGC 3945
Beckman, John E.; Graham, Alister W.; Erwin, Peter +1 more
We present a detailed morphological, photometric, and kinematic analysis of two barred S0 galaxies with large, luminous inner disks inside their bars. We show that these structures, in addition to being geometrically disklike, have exponential profiles (scale lengths ~300-500 pc) distinct from the central, nonexponential bulges. We also find them …
Multiwavelength Spectrum of the Black Hole XTE J1118+480 in Quiescence
Remillard, Ronald A.; McClintock, Jeffrey E.; Orosz, Jerome A. +3 more
We present an X-ray/UV/optical spectrum of the black hole primary in the X-ray nova XTE J1118+480 in quiescence at LX~4×10-9LEdd. The Chandra, Hubble Space Telescope, and Multiple Mirror Telescope spectroscopic observations were performed simultaneously on 2002 January 12 UT. Because this 4.1 hr binary is located a…
Luminous Supersoft X-Ray Sources in External Galaxies
Kong, A. K. H.; Di Stefano, R.
We use a set of conservative criteria to identify luminous supersoft X-ray sources (SSSs) in external galaxies. We test this approach on blackbody models and then apply it to Chandra data from four galaxies: an elliptical galaxy (NGC 4967), two face-on spiral galaxies (M101 and M83), and an interacting galaxy (M51). We find SSSs in every galaxy an…
XMM-Newton Observations of PSR B1823-13: An Asymmetric Synchrotron Nebula around a Vela-like Pulsar
Gaensler, B. M.; Kaspi, V. M.; Pivovaroff, M. J. +2 more
We present a deep observation with the X-Ray Multimirror Mission of PSR B1823-13, a young pulsar with similar properties to the Vela pulsar. We detect two components to the X-ray emission associated with PSR B1823-13: an elongated core of extent 30" immediately surrounding the pulsar embedded in a fainter, diffuse component of emission 5' in exten…
A Turbulent Origin for Flocculent Spiral Structure in Galaxies
Elmegreen, Bruce G.; Elmegreen, Debra Meloy; Leitner, Samuel N.
The flocculent structure of star formation in galaxies has a Fourier transform power spectrum for azimuthal intensity scans with a power-law slope that increases systematically from about -1 at large scales to about -5/3 at small scales. This is the same pattern as in the power spectra for azimuthal scans of H I emission in the Large Magellanic Cl…
Fundamental Properties and Distances of Large Magellanic Cloud Eclipsing Binaries. IV. HV 5936
Ribas, I.; Fitzpatrick, E. L.; Guinan, E. F. +2 more
We have determined the fundamental properties and distance of a fourth eclipsing binary (EB) system in the Large Magellanic Cloud, HV 5936 (~B0.5 V + ~B2 III). As in our previous studies, we combine ``classical'' EB light-curve and radial velocity curve analyses with modeling of the UV/optical spectral energy distribution of HV 5936 to produce a d…
The Ionized Gas and Nuclear Environment in NGC 3783. II. Averaged Hubble Space Telescope/STIS and Far Ultraviolet Spectroscopic Explorer Spectra
Kaiser, Mary Elizabeth; Brandt, W. N.; Kaspi, Shai +14 more
We present observations of the intrinsic absorption in the Seyfert 1 galaxy NGC 3783 obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope and the Far Ultraviolet Spectroscopic Explorer (FUSE). We have combined 18 STIS and five FUSE observations to obtain a high signal-to-noise ratio averaged spectrum spanning…
Trapping of Solar Energetic Particles by the Small-Scale Topology of Solar Wind Turbulence
Matthaeus, W. H.; Ruffolo, D.; Chuychai, P.
The transport of energetic particles perpendicular to the mean magnetic field in space plasmas has long been viewed as a diffusive process. However, there is an apparent conflict between recent observations of solar energetic particles (SEPs): (1) Impulsive solar flares can exhibit ``dropouts'' in which the SEP intensity near Earth repeatedly disa…
Discovery of GRB 020405 and Its Late Red Bump
Piro, L.; Mitrofanov, I.; Axelrod, T. S. +41 more
We present the discovery of GRB 020405 made with the Interplanetary Network (IPN). With a duration of 60 s, the burst appears to be a typical long-duration event. We observed the 75 arcmin2 IPN error region with the Mount Stromlo Observatory's 50 inch robotic telescope and discovered a transient source that subsequently decayed and was …
The Nascent Solar Wind: Origin and Acceleration
Romoli, Marco; Teriaca, Luca; Poletto, Giannina +1 more
High-speed solar wind is known to originate in polar coronal holes, which, however, are made up of two components: bright, high-density regions known as ``plumes'' and dark, weakly emitting low-density regions known as ``interplumes.'' Recent space observations have shown that the width of UV lines is larger in interplume regions, while observatio…