Search Publications
Pulsar Wind Nebulae in Egret Error Boxes
Hessels, Jason W. T.; Ng, C. -Y.; Gaensler, Bryan M. +3 more
A remarkable number of pulsar wind nebulae (PWN) are coincident with EGRET γ-ray sources. X-ray and radio imaging studies of unidentified EGRET sources have resulted in the discovery of at least six new pulsar wind nebulae (PWN). Stationary PWN (SPWN) appear to be associated with steady EGRET sources with hard spectra, typical for γ-ray pulsars. T…
XMM-Newton discovery of soft X-ray absorption in the high-z superluminous Blazar RBS 315
Guainazzi, M.; Piconcelli, E.
We present the analysis and the results of a 20 ks XMM-Newton observation of the extremely X-ray loud (LX ≈ 5 × 1047 erg s-1) flat-spectrum radio quasar RBS 315 at a redshift of 2.69. This EPIC observation has allowed us to strongly constrain the slope of the continuum (Γ = 1.23±0.01) as well as to discover the pre…
Is Arcturus a well-understood K giant?. Test of model atmospheres and potential companion detection by near-infrared interferometry
Eriksson, K.; Decin, L.; Verhoelst, T. +8 more
We present near-IR interferometric measurements of the K1.5 giant Arcturus (α Bootis), obtained at the IOTA interferometer with the FLUOR instrument, in four narrow filters with central wavelengths ranging from 2.03 µm to 2.39 µm. These observations were expected to allow us to quantify the wavelength dependence of the diameter of a ty…
Interplanetary consequences caused by the extremely intense solar activity during October-November 2003
Kojima, Masayoshi; Tokumaru, Munetoshi; Fujiki, Ken'ichi +2 more
We report interplanetary scintillation (IPS) measurements made by the 327 MHz four-station system of the Solar-Terrestrial Environment Laboratory of Nagoya University, during 21 October to 8 November 2003. In this period, solar activity increased greatly owing to the appearance of huge eruptive sunspots on the solar disk. Interplanetary (IP) distu…
Large-Amplitude Velocity Fluctuations in Coronal Loops: Flare Drivers?
Veltri, P.; Malara, F.; Nigro, G.
Recent space observations of coronal lines broadening during a flare occurrence suggest that unresolved nonthermal velocity rises well above the background level before the start of the flare, defined as the start of hard X-ray emission. Using a new shell model to describe the Alfvénic turbulence inside a coronal loop, it is shown that the occurre…
Nonthermal Velocities in Different Temperature Regions of the Solar Lower Transition Region
Doschek, G. A.; Mariska, J. T.; Akiyama, S.
We analyze the relationship between nonthermal velocities derived from spectral lines of ions formed at different temperatures in the solar lower transition region, using spectra from the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectrometer on board the Solar and Heliospheric Observatory (SOHO). We find a high degree of correla…
ADAS analysis of the differential emission measure structure of the inner solar corona. II. A study of the "quiet Sun" inhomogeneities from SOHO CDS-NIS spectra
Lanzafame, A. C.; Brooks, D. H.; Lang, J.
We present a study of the differential emission measure (DEM) of a “quiet Sun” area observed in the extreme ultraviolet at normal incidence by the Coronal Diagnostic Spectrometer (CDS) on the SOHO spacecraft. The data used for this work were taken using the NISATS observing sequence. This takes the full wavelength ranges from both the N…
Oxygen Abundance in Coronal Streamers
Raymond, John C.; Vásquez, Alberto M.
In a previous work we developed a stationary proton-electron MHD model of the solar corona, suitable for the minimum-activity epochs. In the present work, we use empirically derived information from the past solar minimum for the oxygen parameters (temperatures and outflow velocity) to develop an oxygen model in the frame of our previous model. So…
Relation between the solar wind dynamic pressure at Voyager 2 and the energetic particle events at Voyager 1
Wang, C.; Richardson, J. D.; Stone, E. C. +2 more
Starting in 2001, Voyager 1 observed three events characterized by enhanced fluxes of energetic particles. These events suggest that Voyager 1 made a close approach to, or a crossing of, the termination shock. Although the plasma experiment on Voyager 1 is not providing useful data, plasma data from Voyager 2 may shed light on the plasma condition…
Spatial Evidence for Transition Radiation in a Solar Radio Burst
Fleishman, Gregory D.; Nita, Gelu M.; Gary, Dale E.
Microturbulence, i.e., enhanced fluctuations of plasma density and electric and magnetic fields, is of great interest in astrophysical plasmas, but occurs on spatial scales far too small to resolve by remote sensing, e.g., at ~1-100 cm in the solar corona. This Letter reports spatially resolved observations that offer strong support for the presen…