Search Publications
Kinetic parameters of interstellar neutral helium. Review of results obtained during one solar cycle with the Ulysses/GAS-instrument
Witte, M.
The GAS-instrument onboard the space probe Ulysses is designed to measure the local angular distribution of the flow of interstellar neutral He-atoms within ≈3 AU distance from the sun. It allows to infer the kinetic parameters (velocity vector, temperature and density) of these particles outside the heliosphere (``at infinity''). During three obs…
Cosmic Variance in the Great Observatories Origins Deep Survey
Ferguson, Henry C.; Giavalisco, Mauro; Somerville, Rachel S. +3 more
Cosmic variance is the uncertainty in observational estimates of the volume density of extragalactic objects such as galaxies or quasars arising from the underlying large-scale density fluctuations. This is often a significant source of uncertainty, especially in deep galaxy surveys, which tend to cover relatively small areas. We present estimates…
The Team Keck Treasury Redshift Survey of the GOODS-North Field
Davis, Marc; Capak, Peter; Faber, S. M. +19 more
We report the results of an extensive imaging and spectroscopic survey in the Great Observatories Origins Deep Survey (GOODS)-North field completed using DEIMOS on the Keck II telescope. Observations of 2018 targets in a magnitude-limited sample of 2911 objects to RAB=24.4 yield secure redshifts for a sample of 1440 galaxies and active …
Coronal Magnetic Field Measurements
Lin, H.; Kuhn, J. R.; Coulter, R.
A long-standing solar problem has been to measure the coronal magnetic field. We believe it determines the coronal structure and dynamics from the upper chromosphere out into the heliospheric environment. It is only recently that Zeeman splitting observations of infrared coronal emission lines have been successfully used to deduce the coronal magn…
The Dark Matter Distribution in the Central Regions of Galaxy Clusters: Implications for Cold Dark Matter
Smith, Graham P.; Treu, Tommaso; Ellis, Richard S. +1 more
We have undertaken a spectroscopic survey of gravitational arcs in a carefully chosen sample of six clusters, each containing a dominant brightest cluster galaxy. We use these systems to study the relative distributions of dark and baryonic material in the central regions. Three clusters present both radial and tangential arcs and provide particul…
Spatial scale of high-speed flows in the plasma sheet observed by Cluster
Balogh, A.; Zhang, T. L.; Klecker, B. +9 more
Spatial gradients of high-speed flows in the midtail plasma sheet are determined using multipoint observations from the Cluster spacecraft along the ``dawn-dusk'' direction (perpendicular to the main flow and in the plane of the tail current sheet) and along the north-south direction. If we take the average or median of the spatial gradients and a…
Solar radiative output and its variability: evidence and mechanisms
Fröhlich, Claus; Lean, Judith
Electromagnetic radiation from the Sun is Earth’s primary energy source. Space-based radiometric measurements in the past two decades have begun to establish the nature, magnitude and origins of its variability. An 11-year cycle with peak-to-peak amplitude of order 0.1 % is now well established in recent total solar irradiance observations, as are…
Exploring The Saturn System In The Thermal Infrared: The Composite Infrared Spectrometer
Smith, M. D.; Showalter, M. R.; Lellouch, E. +42 more
The Composite Infrared Spectrometer (CIRS) is a remote-sensing Fourier Transform Spectrometer (FTS) on the Cassini orbiter that measures thermal radiation over two decades in wavenumber, from 10 to 1400 cm- 1 (1 mm to 7µ m), with a spectral resolution that can be set from 0.5 to 15.5 cm- 1. The far infrared portion of t…
Probing turbulence in the Coma galaxy cluster
Finoguenov, A.; Böhringer, H.; Miniati, F. +2 more
Spatially-resolved gas pressure maps of the Coma galaxy cluster are obtained from a mosaic of XMM-Newton observations in the scale range between a resolution of 20 kpc and an extent of 2.8 Mpc. A Fourier analysis of the data reveals the presence of a scale-invariant pressure fluctuation spectrum in the range between 40 and 90 kpc and is found to b…
Numerical simulation of the 12 May 1997 interplanetary CME event
Odstrcil, D.; Riley, P.; Zhao, X. P.
Numerical three-dimensional magnetohydrodynamic models are capable of predicting large-scale solar wind structures at Earth, provided that appropriate time-dependent boundary conditions are specified near the Sun. Since knowledge of such conditions is at present insufficient to directly drive the models, various approximations are used. In this pa…