Search Publications
Density Structure of a Preeruption Coronal Flux Rope
Chen, J.; Krall, J.
A density model is developed for a coronal flux rope with a specified magnetic field configuration in the noninteracting limit, for which transverse pressure forces can be neglected and flows are rapid enough (>1 km s-1) to invalidate a hydrostatic solution. In the coronal portion of the flux rope, we find that the plasma density is …
A uniqueness result for a simple force-free magnetic field submitted to a topological constraint
Aly, J. J.
A proof is given of the following statement: if B is a smooth force-free magnetic field contained in a cylindrical domain of axis parallel to z and of star-shaped cross-section, and if B is topologically equivalent to the uniform field B0=B0z, then B=B0. In addition to being a very first step in the general study o…
XMM-Newton Spectroscopy of the Highly Polarized and Luminous Broad Absorption Line Quasar CSO 755
Brandt, W. N.; Vignali, C.; Comastri, A. +4 more
We present the results from XMM-Newton observations of the highly optically polarized broad absorption line quasar (BALQSO) CSO 755. By analyzing its X-ray spectrum with a total of ~3000 photons, we find that this source has the X-ray continuum of a typical radio-quiet quasar, with a photon index of Γ=1.83+0.07-0.06 and a rat…
Three-dimensional estimates of the coronal electron density at times of extreme solar activity
Frazin, R. A.; Butala, M. D.; Kamalabadi, F.
This paper presents quantitative three-dimensional (3-D) reconstructions of the electron density (Ne) in the solar corona between 1.14 and 2.7 solar radii (R⊙) formed from polarized brightness (pB) measurements made by the Mauna Loa Solar Observatory Mark-IV (Mk4) K-coronameter at the time of the extreme solar events of Octob…
X-Ray Observations of Solar Long-Duration Flares
Phillips, K. J. H.; Harra, L. K.; Feldman, U.
Yohkoh X-ray observations during the several-hour decay of six large solar flares show that the main emitting region is in the form of a bright loop-top source whose spatial extent well after the impulsive stage explains most of the broadening of S XV and Ca XIX X-ray lines, which would otherwise imply nonthermal velocities of 100 km s-1
XMM-Newton Observation of IC 310 in the Outer Region of the Perseus Cluster of Galaxies
Ishida, Manabu; Sato, Kosuke; Ohashi, Takaya +3 more
We present results from an XMM-Newton observation of the head-tail radio galaxy IC 310 located in the southwest region of the Perseus cluster. The spectrum is well fitted by an absorbed power-law model with a photon index of 2.50 ± 0.02 without significant absorption excess. The X-ray image shows a point-like emission at IC 310 without any sign of…
Electron densities in EUV coronal bright points
Doyle, J. G.; Del Zanna, G.; Ugarte-Urra, I.
Electron density measurements of six coronal bright points have been obtained using line ratio diagnostics of four ions in the temperature range 1.3-2.0 × 106 K. The results suggest that BP plasma has more similarities to active region plasma than to quiet Sun plasma. Nevertheless, they do not show the exact same behaviour: the increase…
Irregular Mass Transfer in the Polars VV Puppis and V393 Pavonis during the Low State
Pandel, Dirk; Córdova, France A.
The polars VV Pup and V393 Pav were observed with XMM-Newton during states of low accretion with peak X-ray luminosities of ~1×1030 and ~1×1031 ergs s-1, respectively. In both polars, accretion onto the white dwarf was extremely irregular, and the accretion rate varied by more than 1 order of magnitude on timescale…
Rotation Rates of Particles in Saturn's Rings
Ohtsuki, Keiji
Rotational states of particles in Saturn's rings are not directly observable but have been inferred from spacecraft and ground-based observations of their thermal emission. A temperature contrast between night- and daysides of particles in Saturn's C ring during crossing of the planetary shadow has been detected and interpreted as indicating the p…
XMM-Newton and VLT observations of the afterglow of GRB 040827
Covino, S.; D'Avanzo, P.; Caraveo, P. A. +13 more
The field of the Gamma-Ray Burst GRB 040827 was observed with XMM-Newton and with the ESO/VLT starting 6 and 12 h after the burst, respectively. A fading X-ray afterglow is clearly detected with the XMM-Newton/EPIC instrument, with a time decay t-δ, with δ=1.41±0.10. Its spectrum is well described by a power law (photon index Γ=2.3±0.1)…