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Nonlinear guiding center theory of perpendicular diffusion: General properties and comparison with observation
Qin, Gang; Matthaeus, W. H.; Shalchi, Andreas +1 more
A nonlinear guiding center (NLGC) theory for diffusion of charged particles perpendicular to the mean magnetic field was recently proposed. Here, we draw attention to a number of attractive features of this theory: (1) The theory provides a natural mechanism to connect the perpendicular mean free path with the parallel mean free path. In fact, the…
Nitrogen and Oxygen Abundance Variations in the Outer Ejecta of η Carinae: Evidence for Recent Chemical Enrichment
Smith, Nathan; Morse, Jon A.
We present optical spectra of the ionized ``outer ejecta'' of η Car that reveal differences in chemical composition at various positions. In particular, young condensations just outside the dusty Homunculus nebula show strong nitrogen lines and little or no oxygen, but farther away, nitrogen lines weaken and oxygen lines become stronger. The obser…
The metal content of the bulge globular cluster NGC 6528
Minniti, D.; Pasquini, L.; Zoccali, M. +7 more
High resolution spectra of five stars in the bulge globular cluster NGC 6528 were obtained at the 8m VLT UT2-Kueyen telescope with the UVES spectrograph. Out of the five stars, two of them showed evidence of binarity. The target stars belong to the horizontal and red giant branch stages, at 4000 < Tefflt; 4800 K. Multiband V, I, J, H…
Cassini UVIS observations of the Io plasma torus. II. Radial variations
Steffl, Andrew J.; Stewart, A. Ian F.; Bagenal, Fran
On January 14, 2001, shortly after the Cassini spacecraft's closest approach to Jupiter, the Ultraviolet Imaging Spectrometer (UVIS) made a radial scan through the midnight sector of Io plasma torus. The Io torus has not been previously observed at this local time. The UVIS data consist of 2-D spectrally dispersed images of the Io plasma torus in …
The energy balance of polars revisited
Cropper, Mark; Ramsay, Gavin
In the EXOSAT and ROSAT eras, a significant number of polars were found to show a soft/hard X-ray ratio much greater than that expected from the standard accretion shock model. This was known as the `soft X-ray excess'. We have made an snapshot survey of polars using XMM-Newton and determined their soft/hard ratios. We find that less than one in f…
Reconstruction of two-dimensional magnetopause structures from Cluster observations: verification of method
Balogh, A.; Dandouras, I.; Lavraud, B. +7 more
Available from http://www.copernicus.org/site/EGU/annales/22/4/1251.htm?FrameEngine=false;
The Possible Detection of Cosmological Reionization Sources
Panagia, N.; Fall, S. Michael; Stiavelli, M.
We compare the available catalogs of z~6 galaxies in the Hubble Ultra- Deep Field and in the Great Observatories Origins Deep Survey with the expected properties of the sources of cosmological reionization from our previous theoretical study. Our approach is based on the mean surface brightness of the sources required for reionization and depends …
Relativistic O VIII Emission and Ionized Outflow in NGC 4051 Measured with XMM-Newton
Page, M. J.; Mason, K. O.; Cordova, F. A. +4 more
We present XMM-Newton Reflection Grating Spectrometer observations of the soft X-ray spectrum of NGC 4051 and explore their implications for the inner accretion disk and ionized outflow in the active galactic nucleus. We fit the soft X-ray excess with a relativistically broadened O VIII recombination spectrum, including the entire line series and …
Modeling an X-ray flare on Proxima Centauri: Evidence of two flaring loop components and of two heating mechanisms at work
Audard, M.; Güdel, M.; Peres, G. +1 more
We model in detail a flare observed on Proxima Centauri with the EPIC-PN on board XMM-Newton at high statistics and high time resolution and coverage. Time-dependent hydrodynamic loop modeling is used to describe the rise and peak of the light curve, and a large fraction of the decay, including its change of slope and a secondary maximum, over mor…
Ionized gas kinematics and massive star formation in NGC 1530
Knapen, J. H.; Relaño, M.; Beckman, J. E. +1 more
We present emission line mapping of the strongly barred galaxy NGC 1530 obtained using Fabry-Pérot interferometry in H\alpha, at significantly enhanced angular resolution compared with previously published studies. The main point of the work is to examine in detail the non-circular components of the velocity field of the gas, presumably induced by…