Search Publications
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…
Rosetta Ground Segment and Mission Operations
Ferri, P.; Warhaut, M.; Montagnon, E.
At the European Space Operations Centre in Darmstadt (Germany) the activities for ground segment development and mission operations preparation for Rosetta started in 1997. Many of the characteristics of this mission were new to ESOC and have therefore required an early effort in identifying all the necessary facilities and functions. The ground s…
Oblique Propagation and Dissipation of Alfv&én Waves in Coronal Holes
Srivastava, A. K.; Dwivedi, B. N.
We investigate the effect of viscosity and magnetic diffusivity on the oblique propagation and dissipation of Alfvén waves with respect to the normal outward direction, making use of MHD equations, density, temperature and magnetic field structure in coronal holes and underlying magnetic funnels. We find reduction in the damping length scale, grou…
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…
Abundances of planetary nebula M 1-42
Pottasch, S. R.; Bernard-Salas, J.; Roellig, T. L.
The spectra of the planetary nebula M 1-42 is reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope. The aim is to determine the chemical composition of this object. We also make use of ISO, IUE and ground based spectra. Abundances determined from the mid- and far-infrared lines, which are insensitive to …
Comet Hale Bopp in outburst: Imaging the dynamics of icy particles with HST/NICMOS
Campins, H.; Larson, S.; Stolovy, S. R. +3 more
Comet Hale-Bopp was imaged at wavelengths from 1.87 to 2.22 µm by HST/NICMOS in post-perihelion observations starting on UT 1997 August 27.95. Diffraction-limited (∼0 .″2) images were obtained at high signal-to-noise (∼1500) to probe the composition and dynamics of the inner coma and also the size and activity of the nucleus. The velocities …
A description of surface features in north Tyrrhena Terra, Mars: Evidence for extension and lava flooding
Greeley, Ronald; Neukum, Gerhard; Ori, Gian Gabriele +4 more
We studied north Tyrrhena Terra, an approximately 39,000 km 2 area, located in the transition region straddling the Amenthes and Mare Tyrrhenum Mars Chart quadrangles 14 and 22, respectively. The study area comprises ancient terrains with infilled craters, ridges and valleys. Interpretation of orbiter data of ancient terrains is inheren…
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.…
Ion thermalization and wave excitation downstream of Earth's bow shock: A theory for Cluster observations of He2+ acceleration
Lee, Martin A.; Kucharek, Harald; Liu, Yong C. -M. +1 more
It has been well documented that the plasma immediately downstream of Earth's quasi-perpendicular bow shock, which consists of reflected protons and directly transmitted ions with large temperature anisotropies (T⊥/Tz), is unstable to the excitation of ion cyclotron waves. These waves in turn scatter the protons and ions to m…