Search Publications
Ionospheric photoelectrons: Comparing Venus, Earth, Mars and Titan
Coates, A. J.; Barabash, S.; Lundin, R. +6 more
The sunlit portion of planetary ionospheres is sustained by photoionization. This was first confirmed using measurements and modelling at Earth, but recently the Mars Express, Venus Express and Cassini-Huygens missions have revealed the importance of this process at Mars, Venus and Titan, respectively. The primary neutral atmospheric constituents …
Positron annihilation spectrum from the Galactic Centre region observed by SPI/INTEGRAL revisited: annihilation in a cooling ISM?
Sunyaev, R.; Tsygankov, S.; Sazonov, S. +2 more
We analyse SPI/INTEGRAL data on the 511-keV line from the Galactic Centre, accumulated over ∼6 yr of observations. We decompose the X-ray and soft gamma-ray emission of the central part of the Milky Way into relatively compact 'bulge' and more extended 'disc' components and report their spectral properties. The bulge component shows a prominent 51…
Shoreline retreat at Titan's Ontario Lacus and Arrakis Planitia from Cassini Imaging Science Subsystem observations
Hayes, A. G.; McEwen, A. S.; Turtle, E. P. +1 more
Recent observations by Cassini's Imaging Science Subsystem reveal that part of the shoreline of Titan's Ontario Lacus has retreated by several kilometers and may indicate that the dark area that appeared at Arrakis Planitia (80°S, 120°W) in late 2004 has subsequently faded. These changes provide constraints on aspects of Titan's methane cycle, as …
Linear and nonlinear Landau resonance of kinetic Alfvén waves: Consequences for electron distribution and wave spectrum in the solar wind
Crabtree, C.; Rudakov, L.; Mithaiwala, M. +1 more
Kinetic Alfvén wave turbulence in solar wind is considered and it is shown that non-Maxwellian electron distribution function has a significant effect on the dynamics of solar wind plasmas. Linear Landau damping leads to the formation of a plateau in the parallel electron distribution function which diminishes the Landau damping rate significantly…
OH emission from warm and dense gas in the Orion Bar PDR
Le Bourlot, J.; Contursi, A.; Bergin, E. A. +7 more
As part of a far-infrared (FIR) spectral scan with Herschel/PACS, we present the first detection of the hydroxyl radical (OH) towards the Orion Bar photodissociation region (PDR). Five OH (X 2Π; ν = 0) rotational Λ-doublets involving energy levels out to Eu/k ~ 511 K have been detected (at ~65, ~79, ~84, ~119 and ~163 µ…
The Dissipation of Solar Wind Turbulent Fluctuations at Electron Scales
Burgess, David; Camporeale, Enrico
We present two-dimensional fully kinetic particle-in-cell simulations of decaying electromagnetic fluctuations. The computational box is such that wavelengths ranging from electron to ion gyroradii are resolved. The parameters used are realistic for the solar wind, and the ion-to-electron mass ratio is physical. The dissipation of turbulent fluctu…
Narrow-line Seyfert 1 galaxies at hard X-rays
de Rosa, A.; Miniutti, G.; Ubertini, P. +7 more
Narrow-line Seyfert 1 (NLSy1) galaxies are a peculiar class of type 1 active galactic nuclei (broad-line Seyfert 1 galaxies, hereinafter BLSy1). The X-ray properties of individual objects belonging to this class are often extreme and associated with accretion at high Eddington ratios. Here, we present a study on a sample of 14 NLSy1 galaxies selec…
Sorted clastic stripes, lobes and associated gullies in high-latitude craters on Mars: Landforms indicative of very recent, polycyclic ground-ice thaw and liquid flows
Balme, M. R.; Conway, S. J.; Grindrod, P. M. +1 more
Self-organised patterns of stone stripes, polygons, circles and clastic solifluction lobes form by the sorting of clasts from fine-grained sediments in freeze-thaw cycles. We present new High Resolution Imaging Science Experiment (HiRISE) images of Mars which demonstrate that the slopes of high-latitude craters, including Heimdal crater - just 25 …
Observation of H2O in a strongly lensed Herschel-ATLAS source at z = 2.3
Smail, I.; Omont, A.; Clements, D. L. +54 more
The Herschel survey, H-ATLAS, with its large areal coverage, has recently discovered a number of bright, strongly lensed high-z submillimeter galaxies. The strong magnification makes it possible to study molecular species other than CO, which are otherwise difficult to observe in high-z galaxies. Among the lensed galaxies already identified by H-A…
Statistical Comparison of Magnetic Clouds with Interplanetary Coronal Mass Ejections for Solar Cycle 23
Lepping, R. P.; Wu, Chin-Chun
We compare the number and characteristics of interplanetary coronal mass ejections (ICMEs) to those of magnetic clouds (MCs) by using in-situ solar wind plasma and magnetic field observations made at 1 AU during solar cycle 23. We found that ≈ 28% of ICMEs appear to contain MCs, since 103 magnetic clouds (MCs) occurred during 1995 - 2006, and 307 …