Search Publications
Analysis of blinkers and EUV brightenings in the quiet Sun observed with CDS
Solanki, S. K.; Brković, A.; Rüedi, I.
Movies of quiet Sun regions at disc centre obtained with the Coronal Diagnostic Spectrometer (CDS) onboard the SOHO spacecraft are used to study the properties of transient brightenings seen in the extreme ultraviolet (EUV), so-called blinkers, at three different temperatures sampled simultaneously in the chromospheric He I 584.3 Å (2 x 104
Distribution of magnetic field components in the solar wind plasma
Matthaeus, W. H.; Smith, C. W.; Padhye, N. S.
We examine the probability distribution functions (PDFs) of fluctuations of magnetic field components using the Ulysses and Omnitape data sets to evaluate departures from Gaussian distributions. Functional fits as well as moment comparisons (kurtoses) are used in drawing conclusions concerning the degree of non-Gaussianity. Short-timescale fluctua…
FUSE Observations of U Geminorum during Outburst and Decline
Long, Knox S.; Drew, Janet E.; Froning, Cynthia S. +2 more
We have obtained far-ultraviolet (904-1187 Å) spectra of U Gem in outburst with the Far Ultraviolet Spectroscopic Explorer. Three of the observations were acquired during the plateau phase of the outburst, while the fourth was obtained during late outburst decline. The plateau spectra have continuum shapes and fluxes that are approximated by stead…
Investigation of USNO-A2.0 Catalog Positions
Teixeira, R.; Assafin, M.; Camargo, J. I. B. +4 more
We present an investigation of the USNO-A2.0 Catalog positions. We have compared USNO-A2.0 positions with the Astrographic Catalogue-Tycho, with improved HST Guide Star Catalog positions in the ACT frame, and with International Celestial Reference Frame source positions and observational data from Valinhos CCD Meridian Circle, covering all the USN…
Comparison of Empirical Models for Polar and Equatorial Coronal Holes
Romoli, M.; Cranmer, S. R.; Kohl, J. L. +2 more
We present a self-consistent empirical model for several plasma parameters of a large equatorial coronal hole observed on 1999 November 12 near solar maximum. The model was derived from observations with the Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric Observatory. In this Letter, we compare the observations of O VI λλ1032, 1…
Morphological and kinematic signatures of a binary central star in the planetary nebula Hu2-1
Guerrero, Martín A.; Miranda, Luis F.; Vázquez, Roberto +2 more
We present Hα, [Nii] and [Oiii] ground-based and HST archive images, VLA-A 3.6-cm continuum and H92α emission-line data and high-resolution long-slit [Nii] spectra of the planetary nebula Hu2-1. A large number of structural components are identified in the nebula: an outer bipolar and an inner shell, two pairs of collimated bipolar structures at d…
Nuclear star formation in the hotspot galaxy NGC 2903
Knapen, J. H.; Alonso-Herrero, A.; Ryder, S. D.
We present high-resolution near-infrared imaging obtained using adaptive optics and HST/NICMOS, and ground-based spectroscopy of the hotspot galaxy NGC 2903. Our near-infrared resolution imaging enables us to resolve the infrared hotspots into individual young stellar clusters or groups of these. The spatial distribution of the stellar clusters is…
A study of magnetic fluctuations and their anomalous scaling in the solar wind: the Ulysses fast-latitude scan
Balogh, A.; Pagel, C.
The solar wind is a highly turbulent and intermittent medium at frequencies between 10-4 and 10-1 Hz. Power spectra are used to look at fluctuations in the components of the magnetic field at high frequencies over a wide range of latitudes. Results show steady turbulence in the polar regions of the Sun and a more varied envir…
WFPC2 Observations of Massive and Compact Young Star Clusters in M31
Williams, Benjamin F.; Hodge, Paul W.
We present color-magnitude diagrams of four blue massive and compact star clusters in M31: G38, G44, G94, and G293. The diagrams of the four clusters reveal a well-populated upper main sequence and various numbers of supergiants. The U-B and B-V colors of the upper main sequence stars are used to determine reddening estimates of the different line…
Joint EUV/Radio Observations of a Solar Filament
Bocchialini, K.; Harrison, R. A.; Alissandrakis, C. E. +2 more
In this paper we compare simultaneous extreme ultraviolet (EUV) line intensity and microwave observations of a filament on the disk. The EUV line intensities were observed by the CDS and SUMER instruments on board SOHO and the radio data by the Very Large Array and the Nobeyama radioheliograph. The main results of this study are the following: (1)…