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No sodium in the vapour plumes of Enceladus
Johnson, Robert E.; Dougherty, Michele K.; Schneider, Nicholas M. +5 more
The discovery of water vapour and ice particles erupting from Saturn's moon Enceladus fuelled speculation that an internal ocean was the source. Alternatively, the source might be ice warmed, melted or crushed by tectonic motions. Sodium chloride (that is, salt) is expected to be present in a long-lived ocean in contact with a rocky core. Here we …
The first decade of science with Chandra and XMM-Newton
Weisskopf, Martin C.; Schartel, Norbert; Santos-Lleo, Maria +2 more
NASA's Chandra X-ray Observatory and the ESA's X-ray Multi-Mirror Mission (XMM-Newton) made their first observations ten years ago. The complementary capabilities of these observatories allow us to make high-resolution images and precisely measure the energy of cosmic X-rays. Less than 50years after the first detection of an extrasolar X-ray sourc…
Planetary science: Enceladus with a grain of salt
Spencer, John
The observation that water plumes erupt from cracks on Saturn's moon Enceladus has fired speculation about a possible subsurface ocean. The latest searches for sodium salts point to the existence of such an ocean.
Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument
Bibring, J. -P.; Arvidson, R. E.; Langevin, Y. +33 more
Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains…
The presence of methane in the atmosphere of an extrasolar planet
Swain, Mark R.; Vasisht, Gautam; Tinetti, Giovanna
Molecules present in the atmospheres of extrasolar planets are expected to influence strongly the balance of atmospheric radiation, to trace dynamical and chemical processes, and to indicate the presence of disequilibrium effects. As molecules have the potential to reveal atmospheric conditions and chemistry, searching for them is a high priority.…
The unexpected origin of plasmaspheric hiss from discrete chorus emissions
Meredith, Nigel P.; Thorne, Richard M.; Bortnik, Jacob
Plasmaspheric hiss is a type of electromagnetic wave found ubiquitously in the dense plasma region that encircles the Earth, known as the plasmasphere. This important wave is known to remove the high-energy electrons that are trapped along the Earth's magnetic field lines, and therefore helps to reduce the radiation hazards to satellites and human…
A periodicity of ~1hour in X-ray emission from the active galaxy RE J1034+396
Done, Chris; Ward, Martin; Gierliński, Marek +1 more
Active galactic nuclei and quasars are thought to be scaled-up versions of Galactic black hole binaries, powered by accretion onto supermassive black holes with masses of 106-109, as opposed to the ~10 in binaries (here is the solar mass). One example of the similarities between these two types of systems is the characteristi…
The identification of liquid ethane in Titan's Ontario Lacus
Sotin, C.; Barnes, J. W.; Brown, R. H. +7 more
Titan was once thought to have global oceans of light hydrocarbons on its surface, but after 40 close flybys of Titan by the Cassini spacecraft, it has become clear that no such oceans exist. There are, however, features similar to terrestrial lakes and seas, and widespread evidence for fluvial erosion, presumably driven by precipitation of liquid…
An asymmetric distribution of positrons in the Galactic disk revealed by γ-rays
Knödlseder, Jürgen; Winkler, Christoph; Diehl, Roland +8 more
Gamma-ray line radiation at 511keV is the signature of electron-positron annihilation. Such radiation has been known for 30years to come from the general direction of the Galactic Centre, but the origin of the positrons has remained a mystery. Stellar nucleosynthesis, accreting compact objects, and even the annihilation of exotic dark-matter parti…
Slow dust in Enceladus' plume from condensation and wall collisions in tiger stripe fractures
Schmidt, Jürgen; Spahn, Frank; Kempf, Sascha +1 more
One of the spectacular discoveries of the Cassini spacecraft was the plume of water vapour and icy particles (dust) originating near the south pole of Saturn's moon Enceladus. The data imply considerably smaller velocities for the grains than for the vapour, which has been difficult to understand. The gas and dust are too dilute in the plume to in…