Search Publications
SOHO Observations of the Structure and Dynamics of Sunspot Region Atmospheres
Kjeldseth-Moe, O.; Haugan, S. V. H.; Brekke, P. +2 more
We present results from a study of the spatial distributions of line emission and relative line-of-sight velocity in the atmosphere above 17 sunspot regions, from the chromosphere, through the transition region and into the corona, based on simultaneous observations of ten EUV emission lines with the Coronal Diagnostic Spectrometer - CDS on SOHO. …
Proper motions of faint ROSAT WTT stars in the Chamaeleon region
Terranegra, L.; Lattanzi, M. G.; Spagna, A. +2 more
We present proper motions of 59 stars of the ROSAT All-Sky Survey (RASS) located in direction of the Chamaeleon star forming region (SFR) in the magnitude range B=5.1 - 17 mag. Proper motions of the fainter stars were newly derived utilizing survey Schmidt plates from the GSC II plate archive and from a set of special plates taken with the ESO Sch…
The solar ultraviolet spectrum from 1200 Å to 1560 Å: a radiometric comparison between SUMER/SOHO and SOLSTICE/UARS
Wilhelm, K.; Curdt, W.; Schühle, U. +3 more
After short descriptions of the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrometer onboard SOHO (the Solar and Heliospheric Observatory) and the SOLSTICE (Solar-Stellar Irradiance Comparison Experiment) spectrometer on UARS (the Upper Atmosphere Research Satellite), a radiometric comparison is carried out of solar irradiance …
On the Absence of Broad Mg II Emission Line Variability in NGC 3516 during 1996
Koratkar, A. P.; Korista, K. T.; O'Brien, P. T. +2 more
During the 1996 Hubble Space Telescope/Faint Object Spectrograph monitoring campaign of the Seyfert 1 galaxy NGC 3516, the UV continuum showed a factor of 5 variation; correspondingly, the strongest broad UV emission lines (e.g., Lyα, C IV) displayed somewhat weaker, although still significant, variations (a factor of 2). In contrast, no variation…
High-Velocity Line Emission in the Narrow-Line Region of NGC 4151
Gull, T. R.; Kraemer, S. B.; Crenshaw, D. M. +6 more
Narrowband imaging of the nuclear region of NGC 4151 with the Hubble Space Telescope is presented. The filter bandpasses isolate line emission in various high-velocity ranges in several ions. Slitless and long-slit spectra of the region with the Space Telescope Imaging Spectrograph also indicate the locations of high-velocity gas. These emission r…
Direct evidence of the interstellar gas flow velocity in the pickup ion cut-off as observed with SOHO CELIAS CTOF
Bochsler, P.; Klecker, B.; Möbius, E. +9 more
He+ pickup ions as observed with SOHO CELIAS CTOF have been analyzed for the time period DOY 160-190, 1996. During this time of the year the Earth is on the upwind side of the interstellar gas flow with respect to the sun. The high-speed cut-off in the frame of the sun is significantly higher v/Vsw = 2, predicted for pickup i…
The Closest Damped Lyα System
Miller, Eric D.; Bregman, Joel N.; Knezek, Patricia M.
A difficulty of studying damped Lyα systems is that they are distant, so one knows little about the interstellar medium of the galaxy. Here we report on a damped Lyα system in the nearby galaxy NGC 4203, which is so close (vhelio=1117 km s-1) and bright (B0=11.62) that its H I disk has been mapped. The absorption l…
Evolved, single, slowly rotating ... but magnetically active. The G8-giant HR 1362 = EK Eridani revisited
Strassmeier, K. G.; Henry, G. W.; Hall, D. S. +1 more
We rediscuss the unusual case of the slowly rotating late-type giant HR 1362, which exhibits a very unusual high level of magnetic activity. New BVRI photometry from two robotic telescopes from 1991 through 1998 together with previously published photometric data gives a very precise photometric period of 306.9+/-0.4 days. With the aid of high-res…
Swan Observations of the Solar Wind Latitude Distribution and its Evolution Since Launch
Bertaux, Jean-Loup; Lallement, Rosine; Schmidt, Walter +5 more
SWAN is the first space instrument dedicated to the monitoring of the latitude distribution of the solar wind by the Lyman alpha method. The distribution of interstellar H atoms in the solar system is determined by their destruction during ionization charge-exchange with solar wind protons. Maps of sky Ly-α emission have been recorded regularly si…
The HUBBLE SPACE TELESCOPE Extragalactic Distance Scale Key Project. XXIII. The Discovery of Cepheids in NGC 3319
Illingworth, Garth D.; Huchra, John P.; Kennicutt, Robert C. +21 more
The distance to NGC 3319 has been determined from Cepheid variable stars as part of the Hubble Space Telescope Key Project on the Extragalactic Distance Scale. Thirteen and four epochs of observations, using filters F555W (V) and F814W (I), respectively, were made with the Wide Field Planetary Camera 2. Thirty-three Cepheid variables between perio…