Search Publications
Quasi-Thermal Noise Diagnostics in Space Plasmas
Issautier, K.; Moncuquet, M.; Meyer-Vernet, N. +2 more
We present the method of plasma diagnostics by quasi-thermal noise spectroscopy and show examples of application in the solar wind and the Earth's plasmasphere. Using only an electric antenna and a radio receiver, diagnostics of various space environments (magnetized or not) can be obtained in situ. Because of its accuracy, this technique can be u…
Observation of the Halo of NGC 3077 near the ``Garland'' Region Using the Hubble Space Telescope
Madore, Barry F.; Sakai, Shoko
We report the detection of upper main-sequence stars and red giant branch stars in the halo of an amorphous galaxy, NGC 3077. The observations were made using the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The red giant branch luminosity function in the I band shows a sudden discontinuity at I=24.0+/-0.1 mag. Identifying th…
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…