Search Publications
Sunspot Transition Region Oscillations in NOAA 8156
Wilhelm, K.; Kjeldseth-Moe, O.; Brynildsen, N. +2 more
Based on observations obtained with the Solar and Heliospheric Observatory joint observing program for velocity fields in sunspot regions, we have detected 3 minute transition region umbral oscillations in NOAA 8156. Simultaneous recordings of O V λ629 and N V λ1238, λ1242 with the SUMER instrument give the spatial distribution of power in the 3 m…
The ULYSSES Supplement to the BATSE 3B Catalog of Cosmic Gamma-Ray Bursts
Cline, T.; Hurley, K.; Kouveliotou, C. +5 more
We present interplanetary network localization information for 218 gamma-ray bursts in the third BATSE catalog obtained by analyzing the arrival times of these bursts with the Ulysses and Compton Gamma Ray Observatory spacecraft. For any given burst observed by these two spacecraft, arrival time analysis (or ``triangulation'') results in an annulu…
A 2.3 Day Periodic Variability in the Apparently Single Wolf-Rayet Star WR 134: Collapsed Companion or Rotational Modulation?
Moffat, Anthony F. J.; St-Louis, Nicole; Koenigsberger, Gloria +8 more
The apparently single WN 6 type star WR 134 (HD 191765) is distinguished among the Wolf-Rayet star population by its strong, presumably cyclical (\Pscr~2.3 day) spectral variations. A true periodicity--which is still very much debated--would render WR 134 a prime candidate for harboring either a collapsed companion or a rotating, large-scale, inho…
SUMER Observations of the Quiet-Sun Transition Region
Siegmund, O. H. W.; Fisher, G. H.; Griffiths, N. W. +1 more
We present new results from observations of the quiet Sun taken with the SUMER spectrograph on the SOHO spacecraft. This study includes line and continuum emission covering a wide range of temperatures, and the data have been used to create a number of intensity maps with a field of view of ~60''×300'' and a spatial resolutio…
Analysis of the HIPPARCOS Measurements of upsilon Andromedae: A Mass Estimate of Its Outermost Known Planetary Companion
Mazeh, Tsevi; van Leeuwen, Floor; Zucker, Shay +1 more
We present an analysis of Hipparcos astrometric measurements of υ Andromedae, a nearby main-sequence star around which three planet candidates have recently been discovered by means of radial velocity measurements. The stellar orbit associated with the outermost candidate has a period of 1269+/-9 days and a minimum semimajor axis of 0.6 mas. Using…
Heating events in the quiet solar corona: multiwavelength correlations
Krucker, Säm; Benz, Arnold O.
Coronal, transition region and chromospheric lines and centimeter radio emission of the quiet Sun have been simultaneously observed by SoHO and the VLA. The corona above the magnetic network has a higher pressure and is more variable than above the interior of supergranular cells. The Fourier transform in time is found to have steeper spectra in t…
The atmospheric composition and structure of Jupiter and Saturn from ISO observations: a preliminary review
Lellouch, E.; Feuchtgruber, H.; Atreya, S. K. +4 more
Infrared spectra of Jupiter and Saturn have been recorded with the two spectrometers of the Infrared Space Observatory (ISO) in 1995-1998, in the 2.3-180 µm range. Both the grating modes ( R=150-2000) and the Fabry-Pérot modes ( R=8000-30,000) of the two instruments were used. The main results of these observations are (1) the detection of w…
A two-fluid, MHD coronal model
Wu, S. T.; McComas, D. J.; Poletto, G. +2 more
We describe first results from a numerical two-fluid MHD model of the global structure of the solar corona. The model is two-fluid in the sense that it accounts for the collisional energy exchange between protons and electrons. As in our single-fluid model, volumetric heat and momentum sources are required to produce high speed wind from coronal h…
The anomalous intensities of helium lines in the quiet solar transition region
Jordan, C.; MacPherson, K. P.
Previous studies using observations made at low spatial and spectral resolution showed that the resonance lines of Hei and Heii are anomalously strong in the quiet Sun when compared with other transition region lines formed at similar temperatures. Here, the higher spatial and spectral resolution provided by the Coronal Diagnostic Spectrometer (cd…
Large-Scale Dynamics of Active Regions and Small Photospheric Magnetic Features
Meunier, N.
This paper presents an analysis of the dynamics of magnetic features within and outside active regions using full-disk magnetograms obtained by the MDI (Michelson Doppler Imager) instrument on the SOHO spacecraft. The absence of distortion and the short time interval (96 minutes) between images allow us to calculate high-quality cross-correlations…