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The solar corona in cycle 23
Del Zanna, G.; Fludra, A.; Thompson, W. T. +1 more
The Coronal Diagnostic Spectrometer (CDS) on SOHO has been recording EUV spectra and monitoring time variability of EUV line intensities, electron temperature and density in the low solar corona during the rising part of Cycle 23. The four-year data set includes daily synoptic observations in four EUV lines along the central meridian since April 1…
A Reexamination of the ``Planetary'' Lensing Events in M22
Anderson, Jay; Sahu, Kailash C.; King, Ivan R.
We have carried out a further analysis of the tentative, short-term brightenings reported by Sahu and coworkers, which were suggested to be possible lensing of Galactic bulge stars by free-floating planets in the globular cluster M22. Closer examination shows that-unlikely as it may seem-small, pointlike cosmic rays had hit very close to the same …
An IUE and HST Archival Study of the Hot White Dwarf in the Symbiotic Variable RW Hydrae
Sion, E. M.; Mikołajewska, J.; Dumm, T. +1 more
We have carried out an ultraviolet spectroscopic study of the hot white dwarf in the eclipsing S-type symbiotic variable RW Hydrae (Porb=370.2 days). Our study used orbital phase-resolved IUE archival low-resolution and high-resolution spectra and Hubble Space Telescope archival spectra, including all available images obtained at inferi…
Transition region and coronal plasmas: instrumentation and spectral analysis
Dammasch, Ingolf E.; Wilhelm, Klaus; Hassler, Donald M.
The plasma conditions in the solar atmosphere and, in particular, in coronal holes are summarized, before space-borne instrumentation for observing these regions in vacuum-ultraviolet light is briefly introduced with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on the Solar and Heliospheric Observatory (SOHO) as exa…
The Detection of Circumnuclear X-Ray Emission from the Seyfert Galaxy NGC 3516
Nandra, K.; Turner, T. J.; Kraemer, S. B. +7 more
We present the first high-resolution, X-ray image of the circumnuclear regions of the Seyfert 1 galaxy NGC 3516, using the Chandra X-ray Observatory (CXO). All three of the CXO observations reported were performed with one of the two grating assemblies in place, and here we restrict our analysis to undispersed photons (i.e., those detected in the …
Energetic Particle Abundances as Probes of an Interplanetary Shock Wave
Reames, D. V.; Tylka, A. J.
We examine the unique abundance variations of Fe/O and He/H in solar energetic particles from a W09 event of 2001 April 10 that have leaked through the flank of an interplanetary shock launched from W04 on April 9. Shock waves from both events reached the Wind spacecraft on April 11. During the second event, both Fe/O and He/H began at low values …
Phase and Gain Relations between Low-Degree Intensity and Velocity Acoustic Modes during the Solar Activity Cycle
Jiménez, Antonio
Phase and gain relations between low-degree acoustic modes measured as intensity and velocity fluctuations have been carried out using various instruments and techniques. The helioseismic instrument aboard the Solar and Heliospheric Observatory (SOHO) satellite provides an opportunity to observe solar oscillations in intensity and velocity under t…
Solar system objects in the ISOPHOT 170 mu m serendipity survey
Müller, T. G.; Stickel, M.; Hotzel, S.
The ISOPHOT Serendipity Survey (ISOSS) covered approximately 15% of the sky at a wavelength of 170 mu m while the ISO satellite was slewing from one target to the next. By chance, ISOSS slews went over many solar system objects (SSOs). We identified the comets, asteroids and planets in the slews through a fast and effective search procedure based …
Sub-arcsecond atomic hydrogen absorption in the Seyfert galaxies NGC 7674 and NGC 7469
Beswick, R. J.; Pedlar, A.; McDonald, A. R.
Neutral hydrogen has been studied on sub-arcsecond scales in two Seyfert galaxies, NGC 7469 and NGC 7674. The 1.4-GHz continuum emission from these sources agree with higher frequency measurements and shows linear, triple source in NGC 7674 and a compact source surrounded by a weak ring of radio emission in NGC 7469. In both of these sources we de…
SOHO, Yohkoh, Ulysses and Trace: The four solar missions in perspective, and available resources
Domingo, V.
Four solar observing spacecraft, now in operation, have obtained and continue to obtain data during the late phase of solar cycle 22 and hopefully most of cycle 23. The data are available for scientific analysis, practically in an unrestricted manner. A large pool of software suited for the processing and to help programming any data analysis is f…