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An XMM-Newton study of the hard X-ray sky
Cappi, M.; Piconcelli, E.; Dadina, M. +2 more
We report on the spectral properties of a sample of 90 hard X-ray selected serendipitous sources detected in 12 XMM-Newton observations with 1 <≈F2-10simlt 80 x 10-14 erg cm-2 s-1. Approximately 40% of the sources are optically identified with 0.1 <~ z<~ 2 and most of them are classified as broa…
A Multiwavelength Study of the High-Field Magnetic White Dwarf EUVE J0317-85.5 (=RE J0317-853)
Vennes, Stéphane; Christian, D. J.; Wickramasinghe, D. T. +3 more
We present optical and ultraviolet photometry and spectroscopy and optical circular spectropolarimetry of the ultramassive, rapidly rotating, high-field magnetic white dwarf EUVE J0317-85.5. From the combined data sets, we establish an ephemeris for the photometric, spectroscopic, and polarimetric variations with a spin period of 725.7277 s, the f…
New Light on the Stellar Populations in I Zw 18: Deep Near-Infrared Imaging
Hunt, Leslie K.; Thuan, Trinh X.; Izotov, Yuri I.
We present deep JHK images of I Zw 18, the most metal deficient blue compact dwarf galaxy known, and analyze them in conjunction with archival Hubble Space Telescope/Wide Field Planetary Camera 2 optical images. To investigate the stellar populations, we have divided the main body of I Zw 18 into eight regions and fitted the optical, near-infrared…
Detection of molecular hydrogen at z = 1.15 toward HE 0515-4414
Reimers, D.; Baade, R.; Levshakov, S. A. +1 more
A new molecular hydrogen cloud is found in the sub-damped Lyalpha absorber [log N(H I) = 19.88+/-0.05] at the redshift zabs = 1.15 toward the bright quasar HE 0515-4414 (zem = 1.71). More than 30 absorption features in the Lyman band system of H2 are identified in the UV spectrum of this quasar obtained with the Sp…
On the existence of Alfvén waves in the terrestrial foreshock
Balogh, A.; Dandouras, I.; Eastwood, J. P. +2 more
The terrestrial foreshock is characterised by the existence of large amplitude ultra low frequency waves. The majority of such waves are observed to be left-handed in the spacecraft frame, but are in fact intrinsically right-handed and have been identified as fast-magnetosonic waves. More rarely observed are waves that are right-handed in the spac…
Molecular Outflows in the Young Open Cluster IC 348
Stanke, Thomas; Eislöffel, Jochen; McCaughrean, Mark J. +1 more
We present a wide-field survey of the young open cluster IC 348 for molecular H2 outflows. Outflow activity is only found at its southwestern limit, where a new subcluster of embedded sources is in an early phase of its formation. If the IC 348 cluster had been built up by such subclusters forming at different times, this could explain …
Buoyant disruption of magnetic arcades with self-induced shearing
Manchester, Ward
We present the results of magnetohydrodynamic (MHD) simulations of the nonlinear development of instabilities of magnetically sheared arcades and show how they relate to plasmoid ejections and coronal mass ejections (CMEs). To model the arcade disruptions, we capitalize on a family of analytical solutions for initial states; these describe magneti…
Is there really a Lutz-Kelker bias? Reconsidering calibration with trigonometric parallaxes
Smith, Haywood
In the recent literature there are indications of some confusion regarding the Lutz-Kelker bias: whether or not it exists, and if so, what it is and when it should be corrected. Here we carefully reexamine Lutz & Kelker's original work to understand what they actually did, and then look at their later papers and some other works on the subject…
Simultaneous observations of the quasar 3C 273 with INTEGRAL and RXTE
Grindlay, J. E.; Walter, R.; Lund, N. +15 more
INTEGRAL has observed the bright quasar 3C 273 on 3 epochs in January 2003 as one of the first observations of the open programme. The observation on January 5 was simultaneous with RXTE and XMM-Newton observations. We present here a first analysis of the continuum emission as observed by these 3 satellites in the band from =~ 3 keV to =~ 500 keV.…
Penetration of the heliosphere by the interstellar dust stream during solar maximum
Krüger, H.; Grün, E.; Altobelli, N. +1 more
We analyze the Ulysses in situ measurements of interstellar dust in the solar system with respect to the temporal variation of the flux density. The data set that is used covers the time from after Ulysses' fly-by of Jupiter up to the most recent data taken end of November 2002. The decrease in interstellar dust flux observed in 1996 can be explai…