Search Publications
Modulation of Jovian and galactic electrons in the heliosphere: 2. Radial transport of a few MeV electrons
Fichtner, H.; Ferreira, S. E. S.; Potgieter, M. S. +3 more
Previously, the latitudinal transport of ~7 MeV electrons was studied by comparing the results of a newly developed three-dimensional model, based on the numerical solution of Parker's transport equation including the Jovian source, with Ulysses observations. Here, the radial transport of ~16 MeV electrons is studied by comparing the model results…
Interstellar Bubbles in Two Young H II Regions
Danforth, Charles W.; Nazé, Yaël; Chu, You-Hua +3 more
Massive stars are expected to produce wind-blown bubbles in the interstellar medium; however, ring nebulae, suggesting the existence of bubbles, are rarely seen around main-sequence O stars. To search for wind-blown bubbles around main-sequence O stars, we have obtained high-resolution Hubble Space Telescope WFPC2 images and high-dispersion echell…
A new model of solar EUV irradiance variability: 1. Model formulation
Mariska, J. T.; Warren, H. P.; Lean, J.
We present a new model of solar irradiance variability at extreme ultraviolet wavelengths (EUV, 50-1200 Å). In this model, quiet Sun, coronal hole, and active region intensities for optically thin emission lines are computed from emission measure distributions determined from spectrally and spatially resolved observations. For optically thick emis…
Are There Blue, Massive E/S0 Galaxies at z<1? Kinematics of Blue Spheroidal Galaxy Candidates
Gebhardt, Karl; Faber, S. M.; Willmer, Christopher N. A. +5 more
Several recent studies find that 10%-50% of morphologically selected field early-type galaxies at redshifts z<~1 have blue colors indicative of recent star formation. Such ``blue spheroids'' might be massive early-type galaxies with active star formation, perhaps induced by recent merger events. Alternatively, they could be starbursting, low-ma…
Cluster magnetic field observations in the magnetosheath: four-point measurements of mirror structures
Balogh, A.; Horbury, T. S.; Lucek, E. A. +7 more
The Cluster spacecraft have returned the first simultaneous four-point measurements of the magnetosheath. We present an analysis of data recorded on 10 November 2000, when the four spacecrafts observed an interval of strong mirrorlike activity. Correlation analysis between spacecraft pairs is used to examine the scale size of the mirror structures…
Observation of Polar Plumes at High Solar Altitudes
Plunkett, S. P.; Andrews, M. D.; DeForest, C. E.
Using the Large-Angle Spectrometric Coronagraph (LASCO) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft, we have imaged polar plumes extending 30 Rsolar from disk center in the image plane and ~45 Rsolar in three-dimensional space, a factor of 2-3 farther than previous imaging measurements and well into the co…
Seeing Galaxies through Thick and Thin. III. Hubble Space Telescope Imaging of the Dust in Backlit Spiral Galaxies
White, Raymond E., III; Keel, William C.
We present analysis of Wide Field Planetary Camera 2 imaging of two spiral galaxies partially backlit by elliptical or S0 systems in the pairs AM 1316-241 and AM 0500-620, as well as the (probably spiral) foreground system in NGC 1275. Images in B and I are used to determine the reddening curve of dust in these systems. The foreground spiral compo…
Optical spectroscopy and photometry of the neutron star RX J1856.5-3754
Kulkarni, S. R.; van Kerkwijk, M. H.
We present spectroscopy and imaging with the Very Large Telescope (VLT) of the neutron star
Late AGB Magnetic Cycles: Magnetohydrodynamic Solutions for the Hubble Space Telescope Planetary Nebula Rings
García-Segura, Guillermo; López, José Alberto; Franco, José
The Hubble Space Telescope (HST) has revealed the existence of multiple, regularly spaced, and faint concentric shells around some planetary nebulae. Here we present two- (and a half) dimensional magnetohydrodynamic numerical simulations of the effects of a solar-like magnetic cycle, with periodic polarity inversions, in the slow wind of an asympt…
High-resolution spectroscopy of the low-mass X-ray binary EXO 0748-67
Kahn, S. M.; Brinkman, A. C.; den Herder, J. W. +2 more
We present initial results from observations of the low-mass X-ray binary