Search Publications
The Physical Properties of Coronal Streamers. II.
Uzzo, M.; Vourlidas, A.; Strachan, L.
In this paper the plasma properties of three streamers observed in 2003 by the Ultraviolet Coronagraph Spectrometer (UVCS) are presented for five heights from 1.75 to 5.0 Rsolar. The kinetic temperatures for protons (Tk,p) and the O5+ ions (Tk,O) are derived as a function of height with preferential heat…
Serendipitous XMM-Newton Discovery of a Cluster of Galaxies at z = 0.28
Barth, Aaron J.; Humphrey, Philip J.; Buote, David A. +5 more
We report the discovery of a galaxy cluster serendipitously detected as an extended X-ray source in an offset observation of the group NGC 5044. The cluster redshift, z=0.281, determined from the optical spectrum of the brightest cluster galaxy, agrees with that inferred from the X-ray spectrum using the Fe Kα complex of the hot ICM (z=0.27+/-0.01…
Runaway Massive Binaries and Cluster Ejection Scenarios
Ransom, Scott M.; Boyajian, Tabetha S.; Grundstrom, Erika D. +2 more
The production of runaway massive binaries offers key insights into the evolution of close binary stars and open clusters. The stars HD 14633 and HD 15137 are rare examples of such runaway systems, and in this work we investigate the mechanism by which they were ejected from their parent open cluster, NGC 654. We discuss observational characterist…
Empirical Solar Wind Forecasting from the Chromosphere
McIntosh, S. W.; Leamon, R. J.
Recently, we correlated the inferred structure of the solar chromospheric plasma topography with solar wind velocity and composition data measured at 1 AU. We now offer a physical justification of these relationships and present initial results of an empirical prediction model based on them. While still limited by the fundamentally complex physics…
Angular Momentum Transport and Proton-Alpha-Particle Differential Streaming in the Solar Wind
Li, Xing; Habbal, Shadia Rifai; Li, Bo
The interplay between the proton-alpha-particle differential flow speed, vαp, and angular momentum transport in the solar wind is explored by using a three-fluid model. The force introduced by the azimuthal components is found to play an important role in the force balance for ions in interplanetary space, bringing the radial flow speed…
The Wind-ISM Interaction of α Tauri
Zank, Gary P.; Harper, Graham M.; Wood, Brian E. +2 more
Ultraviolet spectra of α Tau (K5 III) obtained by the Hubble Space Telescope (HST) show many emission lines affected by broad absorption from the strong wind of this red giant star. For the Mg II h and k lines there is also a narrow absorption feature in the midst of the wind absorption that has been interpreted as being from α Tau's wind-interste…
Analysis of Erupting Solar Prominences in Terms of an Underlying Flux-Rope Configuration
Sterling, Alphonse C.; Krall, Jonathan
Data from four solar prominence eruptions are analyzed so as to examine the flux-rope configuration at the onset of eruption and to test specific aspects of an analytic flux-rope model of solar eruptions. The model encompasses both prominence eruptions and coronal mass ejections (CMEs) as generic elements of a typical erupting flux-rope structure.…
Broadening of Resonantly Scattered Ultraviolet Emission Lines by Coronal Hole Outflows
Akinari, Nakagawa
Measurements by the Ultraviolet Coronagraph Spectrometer on board the Solar and Heliospheric Observatory have revealed that the widths of several ultraviolet emission lines are unexpectedly large in solar coronal holes. Here we investigate the line-broadening mechanisms for resonantly scattered emissions, which constitute the major part of the cor…
Jets or High-Velocity Flows Revealed in High-Cadence Spectrometer and Imager Co-observations?
Doyle, J. G.; Madjarska, M. S.; Curdt, W. +1 more
We report on active region EUV dynamic events observed simultaneously at high cadence with SOHO SUMER and TRACE. Although the features appear in the TRACE Fe IX/X 171 Å images as jets seen in projection on the solar disk, the SUMER spectral line profiles suggest that the plasma has been driven along a curved large-scale magnetic structure, a preex…
Fourier-Resolved Spectroscopy of Active Galactic Nuclei Using XMM-Newton Data. I. The 3-10 keV Band Results
Papadakis, I. E.; Kazanas, D.; Ioannou, Z.
We present the results from Fourier-resolved spectroscopy of archival XMM-Newton data of five AGNs, namely, Mrk 766, NGC 3516, NGC 3783, NGC 4051, and Ark 564. This work supplements an earlier study of MCG -6-30-15 and of several Galactic black hole candidate sources. Our results exhibit much larger diversity than for Galactic sources, a fact we a…