Search Publications

Storms, polar deposits and the methane cycle in Titan's atmosphere

Griffith, Caitlin Ann

Applications of the wave kinetic approach: From laser wakefields to drift wave turbulencea)

Davies, J. A.; Vaivads, A.; Dunlop, M. W. +8 more

Nonlinear wave-driven processes in plasmas are normally described by either a monochromatic pump wave that couples to other monochromatic waves or as a random phase wave coupling to other random phase waves. An alternative approach involves a random or broadband pump coupling to monochromatic and/or coherent structures in the plasma. This approach…

X-rays from the Power Sources of the Cepheus A Star-Forming Region

Ezoe, Yuichiro; Tsuboi, Yohko; Pravdo, Steven H. +1 more

We report an observation of X-ray emission from the exciting region of Cepheus A with the Chandra/ACIS instrument. What had been an unresolved X-ray source comprising the putative power sources is now resolved into at least three point-like sources, each with similar X-ray properties and differing radio and submillimeter properties. The sources ar…

Solar Flows and Their Effect on Frequencies of Acoustic Modes

Antia, H. M.; Chatterjee, Piyali

We have calculated the effects of large-scale solar flows, such as the meridional circulation, giant convection cells, and solar rotation on the helioseismic splitting coefficients using quasi-degenerate perturbation theory (QDPT). Our investigation reveals that the effect of poloidal flows like the large-scale meridional circulation are difficult…

Magnetic Helicity Exchange Between Neighboring Active Regions

Zhang, H.; Yang, S.; Büchner, J.

Addressing the long-lasting problem of the magnetic helicity distribution in the solar corona, a proof for magnetic helicity exchange between two neighboring emerging active regions (ARs) was found: when AR 9188 emerged, it first started to accumulate positive helicity, while the later neighboring emerging AR 9192 accumulated negative helicity. At…

Normal galaxies in the XMM-Newton fields. X-rays as a star formation indicator

Georgantopoulos, I.; Rovilos, E.; Whiting, M. +4 more

Context: We use the first XMM serendipitous source catalogue (1XMM) to compile a sample of normal X-ray galaxies.
Aims: We seek to expand the database of X-ray selected normal galaxies at intermediate redshifts and examine the relation between X-ray emission and star formation for late-type systems.
Methods: The candidates are selected bas…

Generalized Similarity in Finite Range Solar Wind Magnetohydrodynamic Turbulence

Chapman, S. C.; Nicol, R. M.

Extended or generalized similarity is a ubiquitous but not well understood feature of turbulence that is realized over a finite range of scales. The ULYSSES spacecraft solar polar passes at solar minimum provide in situ observations of evolving anisotropic magnetohydrodynamic turbulence in the solar wind under ideal conditions of fast quiet flow. …

OMEGA long wavelength channel: Data reduction during non-nominal stages

Bibring, Jean-Pierre; Langevin, Yves; Gondet, Brigitte +4 more

The Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument is a visible and near-infrared imaging spectrometer on board the European Mars Express (MEx) mission. The on-board calibration (OBC) performed at the beginning of observations on each orbit reveals that the photometric response of the C channel (1.0-2.5 µ…

Searching for ULF signatures of the cusp: Observations from search coil magnetometers and auroral imagers in Svalbard

Lorentzen, Dag A.; Kim, Hyomin; Engebretson, Mark J. +4 more

Spacecraft traveling through the cusp at a variety of altitudes have consistently found the cusp to be filled with intense, often irregular power in the upper ULF frequency range. Some ground-based studies have observed narrowband waves in this same frequency range in the vicinity of the cusp foot point, but it has not been possible with magnetome…

Multivariate analysis of Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) Venus Express nightside and limb observations

Erard, S.; Drossart, P.; Piccioni, G.

Spectral signatures measured by Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on the nightside and at the limb of Venus are analyzed with Independent Component Analysis. A methodology has been set up to minimize instrumental effects and to interpret the results on the basis of studies of the most common situations in the data set. The…