Search Publications
Why does the intermediate polar V405 Aurigae show a double-peaked spin pulse?
Hellier, Coel; Evans, P. A.
V405 Aurigae is an intermediate polar showing a double-peaked pulsation in soft X-rays and a single-peaked pulsation in harder X-rays. From XMM-Newton observations, we find that the soft band is dominated by blackbody emission from the heated white dwarf surface. Such emission is at a maximum when either magnetic pole points towards us, explaining…
The reprocessing features in the X-ray spectrum of the NELG MCG -5-23-16
Bianchi, S.; Balestra, I.; Matt, G.
We present results from the spectral analysis of the Seyfert 1.9 galaxy MCG -5-23-16, based on ASCA, BeppoSAX, Chandra and XMM-Newton observations. The spectrum of this object shows a complex iron Kα emission line, which is best modeled by a superposition of a narrow and a broad (possibly relativistic) iron line, together with a Compton reflection…
Iron Kα Emission from the Low-Luminosity Active Galaxies M81 and NGC 4579
Schurch, N. J.; Dewangan, G. C.; Griffiths, R. E. +1 more
We report on the XMM-Newton spectroscopy of the low-luminosity active galaxies (LLAGNs) M81 and NGC 4579, both of which have known black hole masses and well-sampled spectral energy distributions (SEDs). The iron Kα line profiles from both LLAGNs can be described in terms of two components: a narrow line at 6.4 keV, and a moderately broad line (FW…
The X-ray emission mechanism in the protostellar jet HH 154
Orlando, S.; Bonito, R.; Peres, G. +2 more
We study the mechanism causing the X-ray emission recently detected in protostellar jets, by performing a detailed modeling of the interaction between a supersonic jet originating from a young stellar object and the ambient medium, for various values of density contrast, ν, between the ambient density and the jet, and of Mach number, M; radiative …
Models for Solar Magnetic Loops. III. Dynamic Models and Coronal Diagnostic Spectrometer Observations
Landini, M.; Landi, E.
In the present work SOHO Coronal Diagnostic Spectrometer (CDS) observations of a quiescent active region loop are compared to a steady state, dynamic loop model. Three different heating functions are adopted: uniform, concentrated at the top, and concentrated at the footpoints. Predicted temperature and density profiles of the selected loop are co…
Chandra observations of five X-ray transient galactic nuclei
Vaughan, S.; Warwick, R. S.; Edelson, R.
We report on exploratory Chandra observations of five galactic nuclei that were found to be X-ray bright during the ROSAT All-Sky Survey (with LX>~ 1043 erg s-1) but subsequently exhibited a dramatic decline in X-ray luminosity. Very little is known about the post-outburst X-ray properties of these enigmatic sou…
The termination shock near 35° latitude
Burlaga, L. F.; Sheeley, N. R.; Wang, Y. -M. +1 more
The termination shock moves outwards and inwards over timescales of a solar cycle in response to the variations in the average solar wind speed. The amplitude is greater than 50 AU near 35° latitude; the maximum (minimum) distance occurs during the rising (declining) phase of the solar cycle. Shock parameters are distinctly different when the shoc…
Radio Observations of Rapid Acceleration in a Slow Filament Eruption/Fast Coronal Mass Ejection Event
Janardhan, P.; Kundu, M. R.; White, S. M. +4 more
We discuss a filament eruption/coronal mass ejection (CME) event associated with a flare of GOES class M2.8 that occurred on 2001 November 17. This event was observed by the Nobeyama Radio Heliograph (NoRH) at 17 and 34 GHz. NoRH observed the filament during its eruption both as a dark feature against the solar disk and a bright feature above the …
Potential barrier in the electrostatic sheath around a magnetospheric spacecraft
Laakso, H.; Escoubet, P.; Hilgers, A. +4 more
Plasma and field measurements on board magnetospheric spacecraft can be influenced by the spacecraft potential and emitted particles such as photoelectrons and secondary electrons. There exist contradictory requirements for, on one hand, minimizing the spacecraft potential and, on the other hand, minimizing perturbations in the sheath and contamin…
On Collisionless Electron-Ion Temperature Equilibration in the Fast Solar Wind
Laming, J. Martin
We explore a mechanism, entirely new to the fast solar wind, of electron heating by lower hybrid waves to explain the shift to higher charge states observed in various elements in the fast wind at 1 AU relative to the original coronal hole plasma. This process is a variation on that previously discussed for two-temperature accretion flows by Begel…