Search Publications
Interplanetary Transport Mechanisms of Solar Energetic Particles
Zhang, M.; Qin, G.; Dwyer, J. R. +1 more
Numerical simulations of charged particle trajectories in a Parker field with model turbulence are used to study the transport mechanisms of solar energetic particles (SEPs): magnetic focusing, pitch-angle diffusive transport due to magnetic fluctuations, and adiabatic cooling. The results of the simulations are compared with analytical formulae f…
Intense high-altitude auroral electric fields - temporal and spatial characteristics
Nilsson, H.; Buchert, S.; Karlsson, T. +5 more
Available from http://www.copernicus.org/site/EGU/annales/22/7/2485.htm?FrameEngine=false;
Evolution and magnetic topology of the M 1.0 flare of October 22, 2002
Aulanier, G.; Schmieder, B.; Del Zanna, G. +2 more
In this paper we analyse an M 1.0 confined flare observed mainly during its gradual phase. We use the data taken during a coordinated observational campaign between ground based instruments (THEMIS and VTT) and space observatories (SoHO/CDS and MDI, TRACE and RHESSI). We use these multi-wavelength observations to study the morphology and evolution…
Nuclear Properties of a Sample of Nearby Spiral Galaxies from Hubble Space Telescope STIS Imaging
Marconi, A.; Capetti, A.; Carollo, C. M. +17 more
We present surface photometry for the central regions of a sample of 48 spiral galaxies (mostly unbarred and barred of type Sbc or Sc) observed with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Surface brightness profiles (SBPs) were derived and modeled with a Nuker law. We also analyzed archival Wide Field Planeta…
The hard X-ray spectrum of the Seyfert galaxy IRAS 18325-5926: reflection from an ionized disc and variable iron K emission
Young, A. J.; Iwasawa, K.; Fabian, A. C. +2 more
We report our analysis of the X-ray spectra of the Seyfert galaxy IRAS 18325-5926 (= Fairall 49) obtained from various X-ray observatories prior to XMM-Newton, including new results from two RXTE and one BeppoSAX observations. A relatively steep continuum slope (Γ~= 2.2) in the 2-15 keV band is confirmed. The continuum spectrum observed with the B…
Observations of the Sun at Vacuum- Ultraviolet Wavelengths from Space. Part I: Concepts and Instrumentation
Wilhelm, Klaus; Marsch, Eckart; Dwivedi, Bhola N. +1 more
Studies of the high-temperature solar atmosphere are to a large extent based on spectroscopic observations of emission lines and continuum radiation in the vacuum-ultraviolet (VUV) wavelength range of the electromagnetic spectrum. In addition, important contributions stem from soft X-ray measurements. Most of the VUV radiation is produced by trans…
Dust enshrouded star-forming activity in Arp 299
Le Floc'h, E.; Sauvage, M.; Vigroux, L. +4 more
We present mid-infrared spectro-imaging (5-16 µm) observations of the infrared luminous interacting system Arp 299 (= Mrk 171 = IC 694+NGC 3690) obtained with the ISOCAM instrument aboard ISO. Our observations show that nearly 40% of the total emission at 7 and 15 µm is diffuse, originating from the interacting disks of the galaxies. M…
XMM-Newton Observations of Two High-Redshift Quasars: RX J1028-0844 and BR 0351-1034
Elvis, M.; Grupe, D.; Mathur, S. +1 more
We report the results of XMM-Newton observations of two high-redshift quasars, one radio-loud, RX J1028.6-0844 (z=4.276) and one radio-quiet, BR 0351-1034 (z=4.351). We find that the evidence for strong excess absorption toward RX J1028-0844 is marginal at best, contrary to previous claims. The superior sensitivity and broader, softer energy range…
Accuracy of the Born and Ray Approximations for Time-Distance Helioseismology of Flows
Birch, A. C.; Felder, G.
Time-distance helioseismology has been used extensively to study mass flows (for example, flows associated with supergranulation), active regions, and sunspots. In nearly all of these studies the sensitivity of travel times to subsurface flows has been modeled using the first-order ray approximation. The Born approximation has been proposed as a m…
The Stellar Content and Star Formation History of the Late-Type Spiral Galaxy NGC 300 from Hubble Space Telescope Observations
Brandner, W.; Martínez-Delgado, D.; Butler, D. J.
We present the first Hubble Space Telescope (HST) WFPC2 V and I photometry for the Sculptor Group galaxy NGC 300 in four fields ranging from the center to the outer edge. We have made the first measurement of the star formation histories in two disk fields: the oldest stars were born at similar epochs and formation activity increased but at differ…