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Interstellar Deuterium, Nitrogen, and Oxygen Abundances toward GD 246, WD 2331-475, HZ 21, and Lanning 23: Results from the FUSE Mission
Howk, J. Christopher; Chayer, Pierre; Hébrard, Guillaume +3 more
The interstellar abundances of D I, N I, and O I in the local ISM are studied using high-resolution spectra of four hot white dwarfs. The spectra of GD 246, WD 2331-475, HZ 21, and Lan 23 were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) in the wavelength range 905-1187 Å. The line of sight to GD 246 probes the Local Interstella…
Atomic Deuterium/Hydrogen in the Galaxy
Linsky, Jeffrey L.
An accurate value of the D/H ratio in the local interstellar medium (LISM) and a better understanding of the D/H variations with position in the Galactic disk and halo are vitally important questions as they provide information on the primordial D/H ratio in the Galaxy at the time of the protosolar nebula, and the amount of astration and mixing in…
XMM-Newton confirmation of soft X-ray excess emission in clusters of galaxies - The discovery of O VII emission from an extended warm baryonic component
Kaastra, J. S.; Tamura, T.; den Herder, J. W. +2 more
We investigate a sample of 14 clusters of galaxies observed with XMM-Newton in a search for soft X-ray excess emission. In five of these clusters a significant soft excess is evident. This soft X-ray excess is compared with the thermal emission from both the hot intracluster gas and any cooling (flow) gas that may be present. A warm (kT=0.2 keV), …
INTEGRAL discovery of a bright highly obscured galactic X-ray binary source IGR J16318-4848
de Plaa, J.; Parmar, A. N.; Tomsick, J. A. +8 more
INTEGRAL regularly scans the Galactic plane to search for new objects and in particular for absorbed sources with the bulk of their emission above 10-20 keV. The first new INTEGRAL source was discovered on 2003 January 29, 0.5degr from the Galactic plane and was further observed in the X-rays with XMM-Newton. This source, IGR J16318-4848, is intri…
Transverse dimensions of chorus in the source region
Gurnett, D. A.; Santolík, O.
We report measurement of whistler-mode chorus by the four Cluster spacecraft at close separations. We focus our analysis on the generation region close to the magnetic equatorial plane at a radial distance of 4.4 Earth's radii. We use both linear and rank correlation analysis to define perpendicular dimensions of the sources of chorus elements bel…
Modelling the rotational modulation of the Sun as a star
Barge, P.; Llebaria, A.; Pagano, I. +2 more
We analyse the time variability of the total solar irradiance (TSI) as measured by VIRGO/SoHO in order to model the variability of the Sun as a star. Apart from the phases near the minimum at the beginning of activity cycle 23, the period of the rotational modulation is significantly different from the solar synodic period as a consequence of the …
The Formation of Nuclear Rings in Barred Spiral Galaxies
Teuben, Peter; Regan, Michael W.
Although nuclear rings of gas and star formation are common in barred spiral galaxies, current theories of why and how they form do not provide the level of detail needed to quantify the effect that these rings can have on the fueling of active galactic nuclei and on the evolution of their host galaxy. In this paper we use detailed modeling to sho…
Far-Ultraviolet Spectra of Fast Coronal Mass Ejections Associated with X-Class Flares
Raymond, J. C.; Dobrzycka, D.; Ciaravella, A. +4 more
The Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory satellite has observed very fast coronal mass ejections (CMEs) associated with X-class flares. These events show spectral signatures different from those seen in most other CMEs in terms of very rapid disruption of the pre-CME streamer, very high Dopple…
Barred Galaxies at z > 0.7: NICMOS Hubble Deep Field-North Observations
Scoville, Nicholas Z.; Sheth, Kartik; Regan, Michael W. +1 more
Previous optical studies found an unexpected deficit of bars at z>0.7. To investigate the effects of band shifting, we have studied the fraction of barred spiral galaxies in the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) Hubble Deep Field-North. At z>0.7, we find at least four barred spiral galaxies, doubling the number prev…
Analyses on the geometrical structure of magnetic field in the current sheet based on cluster measurements
Balogh, A.; Baker, D. N.; Wang, X. +5 more
The geometrical structure of the magnetic field is a critical character in the magnetospheric dynamics. Using the magnetic field data measured by the Cluster constellation satellites, the geometrical structure including the curvature radius, directions of curvature, and normal of the osculating planes of the magnetic field lines within the current…