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The physical conditions in the PDR of W49N
Ceccarelli, C.; Caux, E.; Vastel, C. +2 more
We present ISO-LWS and ground-based SEST observations which probe the Photo Dissociation Region (PDR) of W49N. The ISO-LWS observations consist of low resolution ( ~ 200) grating spectra between 43 mu m and 197 mu m, and high resolution ( ~ 104) Fabry-Pérot spectra of the [CII] 158 mu m and [OI] 63 and 145 mu m lines. The SEST observati…
EIT and SXT Observations of a Quiet-Region Filament Ejection: First Eruption, Then Reconnection
Moore, Ronald L.; Sterling, Alphonse C.; Thompson, Barbara J.
We observe a slow-onset quiet-region filament eruption with the EUV Imaging Telescope (EIT) on the Solar Heliospheric Observatory (SOHO) and the soft X-ray telescope (SXT) on Yohkoh. This event occurred on 1999 April 18 and was likely the origin of a coronal mass ejection detected by SOHO at 08:30 UT on that day. In the EIT observation, one-half o…
Changes to low-ll solar p-mode frequencies over the solar cycle: correlations on different time-scales
Chaplin, W. J.; Elsworth, Y.; Isaak, G. R. +3 more
We have studied variations in the frequencies of low-l solar p modes through the analysis of nine years of helioseismic data collected by the Birmingham Solar Oscillations Network (BiSON)†. This is the first time that such a long data set has been explored with the extra accuracy afforded by fitting the modes to asymmetric profiles. The epoch cove…
B2114+022: a distant radio source gravitationally lensed by a starburst galaxy
Hjorth, Jens; Patnaik, Alok R.; Jackson, Neal J. +8 more
We have discovered a radio source (B2114+022) with a unique structure during the course of the JVAS gravitational lens survey. VLA, MERLIN, VLBA and MERLIN+EVN radio maps reveal four compact components, in a configuration unlike that of any known lens system, or, for that matter, any of the ~15000 radio sources in the JVAS and CLASS surveys. Three…
The velocity field of UGC 6697 revisited
Tarenghi, M.; Boselli, A.; Gavazzi, G. +4 more
The edge-on galaxy UGC 6697 has a peculiar morphological appearance: a high surface brightness SE component and what appears to be a tidal tail with blue color and low surface brightness extending toward the NW, as dramatically evidenced in subarcsecond broad band images taken with the VLT and in a deep Halpha frame. Long-slit spectros…
Hubble Space Telescope STIS Observations of the Wolf-Rayet Star HD 5980 in the Small Magellanic Cloud. II. The Interstellar Medium Components
Walborn, Nolan R.; Morrell, Nidia; Tsvetanov, Zlatan +6 more
Observations of the interstellar and circumstellar absorption components obtained with the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) along the line of sight toward the Wolf-Rayet-luminous blue variable (LBV) system HD 5980 in the Small Magellanic Cloud are analyzed. Velocity components from C I, C I*, C II, C II*, C IV, N …
Polarisation and propagation of lion roars in the dusk side magnetosheath
Balogh, A.; Dandouras, I.; Maksimovic, M. +8 more
We present observations of lion roars obtained in the magnetosheath by the Spectrum Analyser (SA) of the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment aboard Cluster. STAFF-SA calculates, in near real time, the complete auto- and cross-spectral matrix derived from three magnetic and two electric components of the electromagneti…
Photospheric Network as the Energy Source for the quiet-Sun corona
Tarbell, T.; Ryutova, M.; Woo, R. +1 more
We propose a mechanism for the formation of a magnetic energy avalanche based on highly dynamic phenomena within the ubiquitous small-scale network magnetic elements in the quiet photosphere. We suggest that this mechanism may provide constant mass and energy supply for the corona and fast wind. Constantly emerging from sub-surface layers, flux tu…
Three-Fluid 2.5-dimensional Magnetohydrodynamic Model of the Effective Temperature in Coronal Holes
Davila, J. M.; Ofman, L.
Recent SOHO Ultraviolet Coronagraph Spectrometer (UVCS) observations show that protons and minor ions are hot (Tp>106 K, Ti>107 K) and anisotropic in coronal holes. A possible cause of the large perpendicular motions is unresolved Alfvénic fluctuations in the solar wind. Using the three-fluid 2.5-d…
X-Ray Spectral Features from Gamma-Ray Bursts: Predictions of Progenitor Models
Fryer, Chris L.; Böttcher, Markus
We investigate the potentially observable prompt or delayed X-ray spectral features from the currently popular gamma-ray burst (GRB) models. During the evolution of many GRB progenitors, a disk around the central GRB source is produced. Shock heating as the GRB ejecta collide with the disk may produce observable X-ray features. We first summarize …