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Comparisons between MHD model calculations and observations of Cassini flybys of Titan
Dougherty, Michele K.; Hansen, Kenneth C.; Sokolov, Igor V. +6 more
The Cassini spacecraft passed by Titan on 26 October 2004 (Ta flyby) and 13 December 2004 (Tb flyby). In both cases the Cassini Orbiter entered Titan's ionosphere and flew through Titan's dynamic wake region. In this paper, we present our simulation results of these two flybys using our three-dimensional multispecies MHD model. This model is a sli…
Cosmic Rays at High Heliolatitudes
Potgieter, M. S.; Heber, B.
The Ulysses spacecraft has been the first to orbit the Sun over its poles and to explore the heliosphere at these high heliolatitudes. It has now completed two fast latitude scans, one at solar minimum and one at solar maximum. Since its launch in October 1990, this mission has led to several surprising discoveries concerning energetic particles, …
Evolution of magnetic fields and energetics of flares in active region 8210
Régnier, S.; Canfield, R. C.
To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling of the coronal magnetic field of NOAA AR 8210, a highly flare-productive active region. From the photosphere to the corona, the observations give us information about the motion of magnetic elements (photospheric magnetogra…
Average hard X-ray emission from NS LMXBs: observational evidence of different spectral states in NS LMXBs
Titarchuk, L.; Frontera, F.; Goldoni, P. +9 more
Aims.We studied and compared the long-term average hard X-ray (>20 keV) spectra of a sample of twelve bright low-mass X-ray binaries hosting a neutron star (NS). Our sample comprises the six well studied Galactic Z sources and six Atoll sources, four of which are bright (“GX”) bulge sources while two are weaker ones in the 2-10 keV range (H 175…
Young star cluster complexes in NGC 4038/39. Integral field spectroscopy using VIMOS-VLT
Bastian, N.; Maraston, C.; Kissler-Patig, M. +1 more
We present the first results of a survey to obtain Integral Field Spectroscopy of merging galaxies along the Toomre Sequence. In the present work, we concentrate on the star cluster complexes in the Antennae galaxies (NGC 4038/39) in the overlap region as well as the nuclear region of NGC 4038. Using optical spectroscopy we derive the extinction, …
Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. IV. Measurement for Sculptor
Minniti, Dante; Mateo, Mario; Piatek, Slawomir +5 more
This article presents a measurement of the proper motion of the Sculptor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope using the Space Telescope Imaging Spectrograph in the imaging mode. Each of two distinct fields contains a quasi-stellar object that serves as the ``reference point.'' The measured proper mot…
Properties of O VI Absorption in the Local Interstellar Medium
Savage, Blair D.; Lehner, Nicolas
The measurement of absorption over short distances in the local interstellar medium (LISM) provides an excellent opportunity to study the properties of O VI absorption and its kinematic relationship to absorption by tracers of cool and warm gas. We report on the properties of LISM O VI absorption observed with 20 km s-1 resolution Far U…
Production, ionization and redistribution of O 2 in Saturn's ring atmosphere
Luhmann, J. G.; Tokar, R. L.; Johnson, R. E. +10 more
Molecular oxygen produced by the decomposition of icy surfaces is ubiquitous in Saturn's magnetosphere. A model is described for the toroidal O 2 atmosphere indicated by the detection of O2+ and O + over the main rings. The O 2 ring atmosphere is produced primarily by UV photon-induced decomposition of ice on the s…
Black Hole Mass of the Ultraluminous X-Ray Source M82 X-1
Dewangan, Gulab C.; Griffiths, Richard E.; Titarchuk, Lev
We report the first clear evidence for the simultaneous presence of a low-frequency break and a QPO in the fluctuation power spectrum of a well-known ultraluminous X-ray source (ULX) in M82 using long XMM-Newton observations. The break occurs at a frequency of 34.2+6-3 mHz. The QPO has a centroid at νQPO=114.3+/-1.…
Infrared photometry and evolution of mass-losing AGB stars. I. Carbon stars revisited
Ciprini, S.; Guandalini, R.; Busso, M. +2 more
As part of a reanalysis of galactic Asymptotic Giant Branch (AGB) stars at infrared (IR) wavelengths, we discuss a sample (357) of carbon stars for which mass loss rates, near-IR photometry and distance estimates exist. For 252 sources we collected mid-IR fluxes from the MSX (6C) and the ISO-SWS catalogues. Most stars have spectral energy distribu…