Search Publications
Missions
Journals
Publication Years
Enhanced ionization of the Martian nightside ionosphere during solar energetic particle events
Gurnett, D. A.; Futaana, Y.; Němec, F. +2 more
Electron densities in the Martian nightside ionosphere are more than 90% of time too low to be detected by the Mars Advanced Radar for Subsurface and Ionosphere Sounding radar sounder on board the Mars Express spacecraft. However, the relative number of ionograms with peak electron density high enough to be detected represents a good statistical p…
The variable extension of Saturn's electron radiation belts
Krupp, N.; Roussos, E.; Krimigis, S. M. +4 more
Contrary to the permanent MeV ion belts which are relatively stable in intensity over both short and long time scales and are modulated by a single Galactic Cosmic Ray driven source, the electron belts of Saturn appear to be much more complex in both structure and temporal evolution. In order to understand the responses of this system to the diffe…
Accuracy assessment of airborne photogrammetrically derived high-resolution digital elevation models in a high mountain environment
Müller, Johann; Gärtner-Roer, Isabelle; Thee, Patrick +1 more
High-resolution digital elevation models (DEMs) generated by airborne remote sensing are frequently used to analyze landform structures (monotemporal) and geomorphological processes (multitemporal) in remote areas or areas of extreme terrain. In order to assess and quantify such structures and processes it is necessary to know the absolute accurac…
Spectral features in isolated neutron stars induced by inhomogeneous surface temperatures
Rea, Nanda; Viganò, Daniele; Perna, Rosalba +1 more
The thermal X-ray spectra of several isolated neutron stars display deviations from a pure blackbody. The accurate physical interpretation of these spectral features bears profound implications for our understanding of the atmospheric composition, magnetic field strength and topology, and equation of state of dense matter. With specific details va…
Multi-spacecraft Observations of Linear Modes and Sideband Waves in Ion-scale Solar Wind Turbulence
Motschmann, Uwe; Glassmeier, Karl-Heinz; Narita, Yasuhito +1 more
In the scenario of weak turbulence, energy is believed to be cascaded from smaller to larger wave numbers and frequencies due to weak wave-wave interactions. Based on its perturbative treatment one may regard plasma turbulence as a superposition of linear modes (or normal modes) and sideband waves (or nonlinear modes). In this study, we use magnet…
Fresh shallow valleys in the Martian midlatitudes as features formed by meltwater flow beneath ice
Moore, Jeffrey M.; Howard, Alan D.; Hobley, Daniel E. J.
Significant numbers of valleys have been identified in the Martian midlatitudes (30-60°N/S), spatially associated with extant or recent ice accumulations. Many of these valleys date to the Amazonian, but their formation during these cold, dry epochs is problematic. In this study, we look in detail at the form, distribution, and quantitative geomor…
Discovery of X-Ray Emission from the First Be/Black Hole System
Iwasawa, K.; Casares, J.; Paredes, J. M. +3 more
MWC 656 (=HD 215227) was recently discovered to be the first binary system composed of a Be star and a black hole (BH). We observed it with XMM-Newton, and detected a faint X-ray source compatible with the position of the optical star, thus proving it to be the first Be/BH X-ray binary. The spectrum analysis requires a model fit with two component…
Exploratory X-Ray Monitoring of Luminous Radio-quiet Quasars at High Redshift: Initial Results
Brandt, W. N.; Kaspi, Shai; Schneider, Donald P. +6 more
We present initial results from an exploratory X-ray monitoring project of two groups of comparably luminous radio-quiet quasars (RQQs). The first consists of four sources at 4.10 <= z <= 4.35, monitored by Chandra, and the second is a comparison sample of three sources at 1.33 <= z <= 2.74, monitored by Swift. Together with archival X…
Constraint on the primordial gravitational waves from the joint analysis of BICEP2 and Planck HFI 353 GHz dust polarization data
Cheng, Cheng; Huang, Qing-Guo; Wang, Sai
We make a joint analysis of BICEP2 and recently released Planck HFI 353 GHz dust polarization data, and find that there is no evidence for the primordial gravitational waves and the bound on the tensor-to-scalar ratio becomes r < 0.083 at 95% confidence level in the base ΛCDM + tensor model. Extending to the model with running of scalar spectra…
The SLUGGS Survey: HST/ACS Mosaic Imaging of the NGC 3115 Globular Cluster System
Romanowsky, Aaron J.; Brodie, Jean P.; Strader, Jay +6 more
We present Hubble Space Telescope/Advanced Camera for Surveys (HST/ACS) g and z photometry and half-light radii R h measurements of 360 globular cluster (GC) candidates around the nearby S0 galaxy NGC 3115. We also include Subaru/Suprime-Cam g, r, and i photometry of 421 additional candidates. The well-established color bimodality of th…