Search Publications
Background and pickup ion velocity distribution dynamics in Titan's plasma environment: 3D hybrid simulation and comparison with CAPS T9 observations
Hartle, R. E.; Sittler, E. C.; Cooper, J. F. +2 more
In this report we discuss the ion velocity distribution dynamics from the 3D hybrid simulation. In our model the background, pickup, and ionospheric ions are considered as a particles, whereas the electrons are described as a fluid. Inhomogeneous photoionization, electron-impact ionization and charge exchange are included in our model. We also tak…
Temporal changes in the frequencies and widths of the solar p-mode oscillations
Schou, J.; Rodriguez, J.; Scherrer, P. +7 more
We present a study of the temporal changes in the sensitivities of the frequencies and widths of the solar p-mode oscillations to corresponding changes in the levels of solar activity during Solar Cycle 23. From MDI and GONG++ full-disk Dopplergram three-day time series obtained between 1996 and 2008 we have computed a total of 221 sets of m-avera…
Comparisons of Supergranule Characteristics During the Solar Minima of Cycles 22/23 and 23/24
Williams, Peter E.; Pesnell, W. Dean
Supergranulation is a component of solar convection that manifests itself on the photosphere as a cellular network of around 35 Mm across, with a turnover lifetime of 1 - 2 days. It is strongly linked to the structure of the magnetic field. The horizontal, divergent flows within supergranule cells carry local field lines to the cell boundaries, wh…
Accretion, jets and winds: High-energy emission from young stellar objects
Günther, H. M.
This article summarizes the processes of high-energy emission in young stellar objects. Stars of spectral type A and B are called Herbig Ae/Be (HAeBe) stars in this stage, all later spectral types are termed classical T Tauri stars (CTTS). Both types are studied by high-resolution X-ray and UV spectroscopy and modeling. Three mechanisms contribute…
Water in star-forming regions with Herschel
van Dishoeck, E. F.; Kristensen, L. E.
The Herschel Space Observatory is well suited to address several important questions in star- and planet formation, as is evident from its first year of operation. This paper focuses on observations of water, a key molecule in the physics and chemistry of star-formation. In the WISH Key Program, a comprehensive set of water lines is being obtained…
The magnetic configuration of the high-latitude cusp and dayside magnetopause under strong magnetic shears
Lucek, E.; Dunlop, M.; Liu, Z. X. +8 more
This paper investigates the structure of the magnetic field near the magnetopause (MP) by analyzing the multiple-point magnetic measurements from the Cluster mission. In this paper, the spatial distribution of the curvature radius of the MP surface at the noon-midnight meridian and for situations with moderate dynamical pressure of solar wind is i…
Close to the Dredge: Precise X-Ray C and N Abundances in λ Andromeda and Its Precocious Red Giant Branch Mixing Problem
Ness, J. -U.; Drake, Jeremy J.; Eldridge, John J. +2 more
Chandra LETG+HRC-S and XMM-Newton RGS spectra of H-like C and N lines formed in the corona of the primary star of the RS CVn-type binary λ And, a mildly metal-poor G8 III-IV first ascent giant that completed dredge-up ~50 Myr ago, have been used to make a precise measurement of its surface C/N ratio. We obtain the formal result [C/N] = 0.03 ± 0.07…
Landform hierarchy and evolution in Gorgonum and Atlantis basins, Mars
Capitan, Radu Dan; Van De Wiel, Marco
This paper describes the evolution of landforms in Atlantis and Gorgonum basins, using a geomorphologic approach which interprets landform distribution and hierarchy. Rather than looking at the distribution of large-area (>10 6 km 2) geologic sequences, this study focuses on interpreting the local-scale (<10 3
The Internal Proper Motions of Stars in the Open Cluster M35
Harrison, Thomas E.; Benedict, G. Fritz; McArthur, Barbara E. +1 more
Relative proper motions, based on 108 orbits of Hubble Space Telescope Fine Guidance Sensor data extending from 1992 to 2006, are reported for 74 stars in the open cluster M35 (NGC 2168). A subset of 22 of these objects are then used to compute the cluster's internal proper motion dispersions in both right ascension and declination. We find that t…
Titan impacts and escape
Zahnle, Kevin J.; Korycansky, D. G.
We report on hydrodynamic calculations of impacts of large (multi-kilometer) objects on Saturn's moon Titan. We assess escape from Titan, and evaluate the hypothesis that escaping ejecta blackened the leading hemisphere of Iapetus and peppered the surface of Hyperion. We carried out two- and three-dimensional simulations of impactors ranging in si…