Search Publications
The Evolution of Coronal Mass Ejection Density Structures
Gombosi, T. I.; Lugaz, N.; Manchester, W. B., IV
We present a discussion of the time evolution of the mass and energy of a model coronal mass ejection (CME), analyzing both synthetic coronograph images and three-dimensional data of the numerical ideal magnetohydrodynamics (MHD) simulation. Our global steady state coronal model possesses high-latitude coronal holes and a helmet streamer structure…
Decomposition of the Visible and Dark Matter in the Einstein Ring 0047-2808 by Semilinear Inversion
Dye, S.; Warren, S. J.
We measure the mass density profile of the lens galaxy in the Einstein ring system 0047-2808 using our semilinear inversion method developed in an earlier paper. By introducing an adaptively gridded source plane, we are able to eliminate the need for regularization of the inversion. This removes the problem of a poorly defined number of degrees of…
The X-Ray Emissions from the M87 Jet: Diagnostics and Physical Interpretation
Perlman, Eric S.; Wilson, Andrew S.
We reanalyze the deep Chandra observations of the M87 jet, first examined by Wilson & Yang in 2002. By employing an analysis chain that also includes image deconvolution, knots HST-1 and I are fully separated from adjacent emission. We derive the spatially resolved X-ray spectrum of the jet using the most recent response functions and find sli…
Ultraviolet Imaging Spectroscopy Shows an Active Saturnian System
West, Robert A.; Colwell, Joshua E.; Pryor, Wayne R. +13 more
Neutral oxygen in the saturnian system shows variability, and the total number of oxygen atoms peaks at 4 × 1034. Saturn's aurora brightens in response to solar-wind forcing, and the auroral spectrum resembles Jupiter's. Phoebe's surface shows variable water-ice content, and the data indicate it originated in the outer solar system. Sat…
Characteristic magnetic field and speed properties of interplanetary coronal mass ejections and their sheath regions
Owens, M. J.; Crooker, N. U.; Siscoe, G. L. +2 more
Prediction of the solar wind conditions in near-Earth space, arising from both quasi-steady and transient structures, is essential for space weather forecasting. To achieve forecast lead times of a day or more, such predictions must be made on the basis of remote solar observations. A number of empirical prediction schemes have been proposed to fo…
An HST Search for Supernovae Accompanying X-Ray Flashes
Cenko, S. B.; Peterson, B. A.; Price, P. A. +24 more
We present the results from a Hubble Space Telescope ACS search for supernovae associated with X-ray flashes 020903, 040701, 040812, and 040916. We find strong evidence that XRF 020903 (z=0.25) was associated with a SN 1998bw-like supernova and confirm this using optical spectroscopy at t~25 days. We find no evidence, however, for SN 1998bw-like s…
Contribution of nonadiabatic ions to the cross-tail current in an O+ dominated thin current sheet
Lundin, R.; Balogh, A.; Klecker, B. +8 more
During storm times, O+ can dominate both the pressure and the density in the plasma sheet. Because of the contribution from ion outflow, the plasma sheet is already oxygen-rich prior to substorm onset. At substorm onset the fraction of O+ contributing to the pressure and density increases. In the O+ dominated thin …
Global structure of Jupiter's magnetospheric current sheet
Khurana, Krishan K.; Schwarzl, Hannes K.
Jupiter's magnetosphere contains a gigantic sheet-like structure located near its dipole magnetic equator that contains most of the plasma and energetic particles swirling in Jupiter's magnetosphere. Called the "current sheet," it behaves like a rigid structure inside a radial distance of ∼50 RJ where the periodic reversals of the B
Kelu-1 Is a Binary L Dwarf: First Brown Dwarf Science from Laser Guide Star Adaptive Optics
Leggett, S. K.; Liu, Michael C.
We present near-infrared (1-2.4 µm) imaging of the L dwarf Kelu-1 obtained with the Keck sodium laser guide star adaptive optics (LGS AO) system as part of a high angular resolution survey for substellar binaries. Kelu-1 was one of the first free-floating L dwarfs identified, and the origin of its overluminosity compared to objects of simila…
Magnetic Reconnection Rate and Flux-Rope Acceleration of Two-Ribbon Flares
Lin, Jun; Xu, Yan; Qiu, Jiong +3 more
Forbes & Lin derived simple equations to link the properties of magnetic reconnection in the corona to observed signatures of solar flares. We measured the photospheric magnetic fields and the flare ribbon separation speeds then applied these equations to derive two physical terms for the magnetic reconnection rates: the rate of magnetic flux …