Search Publications
On the origin of the X-ray emission from a narrow-line radio quasar at z > 1
Barcons, X.; Carballo, R.; Warwick, R. S. +5 more
We present new XMM-Newton X-ray observations of the z= 1.246 narrow-line radio quasar RX J1011.2+5545 serendipitously discovered by ROSAT. The flat X-ray spectrum previously measured by ROSAT and ASCA is shown to be the result of a steep Γ~ 1.8 power-law spectrum seen through a moderate intrinsic absorbing column (NH~ 4 × 1021
Modulation effects of a changing solar wind speed on low-energy electrons
Ferreira, S. E. S.; Potgieter, M. S.; Moeketsi, D. M.
The heliospheric modulation of galactic and jovian electrons is studied using a fully three-dimensional, steady-state model based on Parker's transport equation including the jovian electron source. The model is used to study the transport of 7 MeV joviair and galactic electrons in the heliosphere by changing the solar wind speed profile from sola…
XMM- Newton observations of open clusters
Pallavicini, R.; Franciosini, E.; Randich, S.
We present observations of stellar clusters obtained with XMM- Newton as part of the Guaranteed Time program. We have obtained EPIC observations of the open clusters Praesepe, a Per, o Ori and Hyades and of the Taurus-Auriga star-forming region. The results of the analysis are presented and discussed, with emphasis on the imaging data. In all clus…
Fine structure of the diamagnetic cavity boundary in comet Halley
Neubauer, F. M.; Gombosi, T. I.; Israelevich, P. L. +2 more
We calculated the electric current density in the diamagnetic cavity boundary layer (DCBL) using magnetic field data obtained during the Giotto mission to comet Halley. This current possesses both the component perpendicular to the local magnetic field and the parallel component. The perpendicular current is responsible for the screening of the di…
High-resolution XMM-Newton X-ray spectra of τ SCORPII
Raassen, A. J. J.; Mewe, R.; Güdel, M. +3 more
The first high-resolution X-ray spectra of the B0.2V star τ Scorpii obtained during 22.5ks on Aug. 20, 2001 with the RGS GRATING and the EPIC-MOS CCD spectrometers on board XMM-Newton exhibit bright emission lines of the H- and He-like ions of C, N, O, Ne, Mg, and Si, as well as Fe XVII and Fe XVIII lines. The emission line and continuum spectra h…
Shadowing of the Nascent Jet in NGC 4261 by a Line-emitting Supersonic Accretion Disk
Fromerth, Michael J.; Melia, Fulvio; Liu, Siming
NGC 4261 (3C 270) is a low-luminosity radio galaxy with two symmetric kiloparsec-scale jets. Earlier Hubble Space Telescope observations indicated the presence of a 100 pc scale disk of cool dust and gas surrounding a central, supermassive (~4.9×108 Msolar) black hole. The recent detection of free-free radio absorption by a s…
High Precision with the Whole Earth Telescope: Lessons and Some Results from XCov20 for the roAp Star HR 1217
Kepler, S. O.; Kawaler, S. D.; Winget, D. E. +41 more
HR 1217 is a prototypical rapidly oscillating Ap star that has presented a test to the theory of nonradial stellar pulsation. Prior observations showed a clear pattern of five modes with alternating frequency spacings of 33.3 mu Hz and 34.6 mu Hz, with a sixth mode at a problematic spacing of 50.0 mu Hz (which equals 1.5 times 33.3 mu Hz) to the h…
Quasar hosts: differences between radio-loud and radio-quiet galaxies
Kukula, Marek J.
Strong evidence exists that radio-loud quasars and FR II radio galaxies differ only in the orientation of their central AGN, and HST studies of quasar hosts have confirmed that there are no significant differences between radio galaxies and the massive elliptical galaxies which host RLQs. Detailed studies of radio-quiet quasars show that these pow…
Shock acceleration of energetic particles in wave heated corona
Laitinen, T.; Vainio, R.
The solar wind wave heating models require substantial amount of wave power in order to efficiently heat and accelerate solar wind. The level of fluctuations is however limited by energetic particle observations. The simplest cyclotron sweep models result in convection-dominated transport, contradicting observations. However, models incorporating …
Estimating the Interstellar Extinction and the Contribution from an Accretion Shock to the Formation of Emission Continuum in DS Tau and DG Tau
Kravtsova, A. S.
We analyze the UV spectra of the young stars DG Tau and DS Tau taken with the STIS spectrograph from the Hubble Space Telescope. For these stars, we found the upper limits of the interstellar extinction A_V. Their values proved to be lower than those obtained by other authors from optical observations. For DS Tau, DG Tau, and TW Hya, we also deter…