Search Publications
Eruptions arising from tidally controlled periodic openings of rifts on Enceladus
Helfenstein, P.; Bills, B. G.; Hurford, T. A. +2 more
In 2005, plumes were detected near the south polar region of Enceladus, a small icy satellite of Saturn. Observations of the south pole revealed large rifts in the crust, informally called `tiger stripes', which exhibit higher temperatures than the surrounding terrain and are probably sources of the observed eruptions. Models of the ultimate inter…
The loss of ions from Venus through the plasma wake
Coates, A. J.; Kallio, E.; Fedorov, A. +47 more
Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. P…
An unusually brilliant transient in the galaxy M85
Cenko, S. B.; Sanders, D. B.; Gal-Yam, A. +11 more
Historically, variable and transient sources have both surprised astronomers and provided new views of the heavens. Here we report the discovery of an optical transient in the outskirts of the lenticular galaxy Messier 85 in the Virgo cluster. With a peak absolute R magnitude of -12, this event is distinctly brighter than novae, but fainter than t…
Association of the jets of Enceladus with the warmest regions on its south-polar fractures
Porco, Carolyn C.; Spitale, Joseph N.
Jets of material have been seen emanating from the south-polar terrain of Saturn's satellite Enceladus. Observations have shown that this region is anomalously warm, with the hottest measured temperatures coinciding with the four `tiger stripe' fractures, named Alexandria, Cairo, Baghdad and Damascus, that straddle the region. Here we use Cassini …
The signature of hot hydrogen in the atmosphere of the extrasolar planet HD 209458b
Sing, David K.; Ballester, Gilda E.; Herbert, Floyd
About ten per cent of the known extrasolar planets are gas giants that orbit very close to their parent stars. The atmospheres of these `hot Jupiters' are heated by the immense stellar irradiation. In the case of the planet HD 209458b, this energy deposition results in a hydrodynamic state in the upper atmosphere, allowing for sizeable expansion a…
Morphology and dynamics of the upper cloud layer of Venus
Jaumann, R.; Keller, H. U.; Thomas, N. +7 more
Venus is completely covered by a thick cloud layer, of which the upper part is composed of sulphuric acid and some unknown aerosols. The cloud tops are in fast retrograde rotation (super-rotation), but the factors responsible for this super-rotation are unknown. Here we report observations of Venus with the Venus Monitoring Camera on board the Ven…
The structure of Venus' middle atmosphere and ionosphere
Pätzold, M.; Bird, M. K.; Asmar, S. W. +8 more
The atmosphere and ionosphere of Venus have been studied in the past by spacecraft with remote sensing or in situ techniques. These early missions, however, have left us with questions about, for example, the atmospheric structure in the transition region from the upper troposphere to the lower mesosphere (50-90km) and the remarkably variable stru…
South-polar features on Venus similar to those near the north pole
Baines, K. H.; Langevin, Y.; Lopez-Valverde, M. A. +102 more
Venus has no seasons, slow rotation and a very massive atmosphere, which is mainly carbon dioxide with clouds primarily of sulphuric acid droplets. Infrared observations by previous missions to Venus revealed a bright `dipole' feature surrounded by a cold `collar' at its north pole. The polar dipole is a `double-eye' feature at the centre of a vas…
Lightning on Venus inferred from whistler-mode waves in the ionosphere
Russell, C. T.; Wei, H. Y.; Zhang, T. L. +3 more
The occurrence of lightning in a planetary atmosphere enables chemical processes to take place that would not occur under standard temperatures and pressures. Although much evidence has been reported for lightning on Venus, some searches have been negative and the existence of lightning has remained controversial. A definitive detection would be t…
A dynamic upper atmosphere of Venus as revealed by VIRTIS on Venus Express
Baines, K. H.; Langevin, Y.; Lopez-Valverde, M. A. +101 more
The upper atmosphere of a planet is a transition region in which energy is transferred between the deeper atmosphere and outer space. Molecular emissions from the upper atmosphere (90-120km altitude) of Venus can be used to investigate the energetics and to trace the circulation of this hitherto little-studied region. Previous spacecraft and groun…