Search Publications
Characteristic Times of Gradual Solar Energetic Particle Events and Their Dependence on Associated Coronal Mass Ejection Properties
Kahler, S. W.
We use 20 MeV proton intensities from the EPACT instrument on Wind and coronal mass ejections (CMEs) from the LASCO coronagraph on SOHO observed during 1998-2002 to statistically determine three characteristic times of gradual solar energetic particle (SEP) events as functions of solar source longitude: (1) TO, the time from associated …
Luminosity Functions of the Galaxy Cluster MS 1054-0321 at z=0.83 based on ACS Photometry
Goto, Tomotsugu; Ford, H. C.; Demarco, R. +41 more
We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive z=0.83 cluster MS 1054-0321. Our analyses are based on imaging performed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST) in the F606W, F775W,…
Helium Line Formation and Abundance in a Solar Active Region
Andretta, V.; Teriaca, L.; Mauas, P. J. D. +3 more
An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca II K, Hα, and Na I D, as well as He I 10830, 5876, 584, and He II 304 Å lines hav…
A Small X-Ray Corona of the Narrow-Angle Tail Radio Galaxy NGC 1265 Soaring through the Perseus Cluster
Sun, M.; Jones, C.; Jerius, D.
A deep Chandra observation of NGC 1265 (3C 83.1B), the prototype for the narrow-angle tail (NAT) radio galaxy, reveals a small cool X-ray thermal corona (~0.6 keV) embedded in the hot ICM of the Perseus cluster (~6.7 keV). The corona is asymmetric with a sharp edge (~2.2", or 0.8 kpc from the nucleus) to the south and an extension to the north (at…
Magnetic Properties at Footpoints of Hot and Cool Loops
Tsuneta, Saku; Katsukawa, Yukio
Observations of the solar corona with Yohkoh, the Solar and Heliospheric Observatory, and the Transition Region and Coronal Explorer (TRACE) have revealed that individual coronal loops of active regions have their own temperatures from 1 to 5 MK. The hot (2-5 MK) Soft X-Ray Telescope (SXT) loops appear to require more heating energy than the cool …
High-Cadence Radio Observations of an EIT Wave
Thompson, B. J.; White, S. M.
Sensitive radio observations of the 1997 September 24 EIT wave show its velocity to be 830 km s-1. The wave first appears a short distance from the flare site, and its trajectory projects back to the flare site at the peak of the impulsive phase. The radio spectrum appears to be consistent with optically thin coronal emission rather tha…
Theoretical Interpretation of the Luminosity and Spectral Properties of GRB 031203
Ruffini, Remo; Bernardini, Maria Grazia; Fraschetti, Federico +3 more
The X-ray and gamma-ray observations of the source GRB 031203 by INTEGRAL are interpreted within our theoretical model. In addition to a complete spacetime parameterization of the GRB, we specifically assume that the afterglow emission originates from a thermal spectrum in the comoving frame of the expanding baryonic matter shell. By determining t…
X-Ray Timing, Spectroscopy, and Photometry of the Anomalous X-Ray Pulsar Candidate CXOU J010043.1-721134
Ransom, S. M.; Gaensler, B. M.; Kaspi, V. M. +2 more
We present new X-ray timing and spectral results on the 8.0 s X-ray pulsar CXOU J010043.1-721134 from a series of observations using the Chandra X-Ray Observatory. We found a spin period in 2004 January of 8.020392+/-0.000009 s. A comparison of this to the 2001 Chandra observations implies a period derivative P˙=(1.88+/-0.08)×10-11 s s<…
On the Combination of Differential Emission Measure Analysis and Rotational Tomography for Three-dimensional Solar EUV Imaging
Frazin, R. A.; Weber, M. A.; Kamalabadi, F.
Conventional differential emission measure (DEM) analysis allows one to determine the amount of plasma as a function of temperature along a given line of sight. A completely different technique called solar rotational tomography (SRT) exploits the view angles provided by solar rotation to determine the spatial distribution of emissivity in three d…
The First Precise Determination of an Optical-Far-Ultraviolet Extinction Curve Beyond the Local Group (z=0.83)
Kochanek, C. S.; Arribas, S.; Muñoz, J. A. +3 more
We present the optical-far-ultraviolet extinction curve of the dust in the lens galaxy of the gravitational lens system SBS 0909+532 (z=0.83). Extending our previous optical-UV estimate (from λ-10~2 to 5 µm-1) into the far ultraviolet (from λ-10~5 to 8 µm-1) is crucial f…