Search Publications
Solar cycle variations of the energetic H/He intensity ratio at high heliolatitudes and in the ecliptic plane
Lario, D.; Roelof, E. C.; Maclennan, C. G. +3 more
We study the variability of the heliospheric energetic proton-to-helium abundance ratios during different phases of the solar cycle. We use energetic particle, solar wind, and magnetic field data from the Ulysses, ACE and IMP-8 spacecraft to compare the H/He intensity ratio at high heliographic latitudes and in the ecliptic plane. During the first…
A possible way of understanding the differential motion of minor ions in the solar wind
Tu, C. -Y.; Marsch, E.; Wang, L. -H.
Measurements with Solar and Heliospheric Observatory (SOHO)/Charge, Element, and Isotope Analysis System (CELIAS) in high-speed solar wind show that some minor ions such as O6+ have a relatively high drift velocity; however, other ions such as Fe9+ tend to lag behind oxygen by a few tens of km/s [, 1998]. This subtle observat…
The optical jet in 3C 31 on 15 arcsec scales
Croston, J. H.; Birkinshaw, M.; Davies, R. L. +1 more
Evidence has been found for optical emission from the northern radio jet of 3C 31, the radio source associated with NGC 383. The jet emerges from the dust disc and ring of emission at a radius of 5 arcsec, and within 10.4 arcsec is measured to have a B-band flux of 2.1 µJy and an R-band flux of 2.3 µJy. The radio-to-optical spectral in…
Heliospheric Langmuir wave observations from the Ulysses spacecraft
McComas, D. J.; Lin, Naiguo; MacDowall, R. J.
Langmuir waves are electrostatic plasma oscillations produced by unstable electron beams in the solar wind and elsewhere. Typical electron sources are solar flares, shocks, and magnetic holes. In this paper, we present an overview of the Langmuir waves observed by Ulysses during both its solar minimum and solar maximum orbits. Langmuir waves in ma…
Atomic Data and Spectral Line Intensities for S XI
Bhatia, A. K.; Landi, E.
Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for S XI. The configurations included are 2s22p2, 2s2p3, 2p4, 2s22p3l, and 2s22p4l (l=s, p, d), giving rise to 72 fine-structure levels in intermediate coup…
CCD-Based Astrometric Measurement of Photographic Plates
Calderón, J. H.; Bustos Fierro, I. H.
We have developed a methodology for the astrometric measurement of photographic plates making use of a CCD camera. In order to measure a complete 2°x 2° plate a mosaic of 8×8 frames with 50% overlap in both coordinates was taken. The detection and centering of stellar images was performed with SExtractor, and by means of our own software triple …
Using Optical and Near-Infrared Photometry to Test MACHO Lens Candidates
Sarajedini, Ata; von Hippel, Ted; Ruiz, Maria Teresa
We obtained new VLT/ISAAC H-band observations for five MACHO LMC source stars and adjacent LMC field regions. After combining our near-IR photometry with Hubble Space Telescope/PC BVRI optical photometry, we compared the MACHO objects to the adjacent field stars in a variety of color-magnitude and color-color diagrams. These diagnostic diagrams we…
Low energy charged particles in the high latitude heliosphere: Comparing solar maximum and solar minimum
Lanzerotti, L. J.; Gold, R. E.; Maclennan, C. G.
Low energy charged particles in the global (3-D) heliosphere within ~2.3 AU of the Sun are compared during the two fast latitude scans by the Ulysses spacecraft at solar minimum and maximum. This comparison of data taken by the HISCALE instrument illustrates quantitatively the differences in the population of the heliosphere during the only two so…
First results from the IBIS/ISGRI data obtained during the Galactic Plane Scan. II. The Vela region
Goldoni, P.; Rodriguez, J.; Foschini, L. +14 more
We report on INTEGRAL/IBIS observations of the Vela region during a Galactic Plane Scan (hereafter GPS) presenting the IBIS in-flight performances during these operations. Among all the known sources in the field of view we clearly detect 4U 0836-429, Vela X-1, Cen X-3, GX 301-2, 1E 1145.1-6141, and H0918-549 in the 20-40 keV energy range. Only Ve…
Addendum: ``Discovery of a Possible Anomalous X-Ray Pulsar in the Small Magellanic Cloud'' (ApJ, 574, L29 [2002])
Fox, D. W.; Lamb, R. C.; Macomb, D. J. +1 more
In the above-mentioned Letter, two frequencies for this source were reported, 0.125 and 0.184 Hz. These frequencies form an alias pair around the Nyquist frequency of the Chandra ACIS-I instrument. New data for this source from the XMM-Newton satellite taken 189.9 days after the original Chandra observation decisively rule in favor of the lower fr…