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Large dust particles around comets
Moreno, F.; Ortiz, J. L.; Molina, A. +1 more
A expression to estimate the maximum diameter, dmax, of the boulders ejected from comets is shown. Special attention is devoted to discuss the influence of the nucleus rotation in the determination of the size of the largest particles. An increase of the dmax about 40% is found for comets spinning with a six hours period. Particularly, these expre…
The physics of the HII regions: the photoionization equilibrium in the HII regions of M51
Gutiérrez, L.; Beckman, J. E.
A general overview of the physical properties of the HII regions is presented here, emphasizing the various general models made to explain their structure and behaviour. The Lyman continuum effective extinction, representing a measure of the extinguished or lost fraction of the ionizing flux, is explained briefly, and the results of a study perfor…
Lecture Notes and Essays in Astrophysics.III. 3rd Symposium of the Astrophysics Group of the Spanish Royal Physical Society (RSEF).
Manteiga, M.; Ulla, A.
The Third volume of "Lecture Notes and Essays in Astrophysics" highlights some important contributions of Spanish astrophysicists to Planetology, Solar and Stellar Physics, Extragalactic Astronomy, Cosmology and astronomical instrumentation. After decades without a dedicated mission, Venus is again in fashion. On the one hand, Ricardo Hueso and co…
The upper atmosphere of Venus observed by Venus Express
López-Valverde, M. A.; Gilli, G.; García-Comas, M. +3 more
The upper atmosphere of Venus is still nowadays a highly unknown region in the scientific context of the terrestrial planetary atmospheres. The Earth's stratosphere and mesosphere continue being studied with increasingly sophisticated sounders and in-situ instrumentation. Also on Mars, its intensive on-going exploration is gathering a whole new se…
The atmosphere of Venus: winds and clouds observed by VIRTIS/VENUS EXPRESS
Hueso, R.; Sánchez-Lavega, A.; Pérez-Hoyos, S. +1 more
After decades without a dedicated space mission, Venus, sometimes referred as Earth's twin planet, is again the subject of intense exploration. Venus Express (VEX), a mission of the European Space Agency, was launched in November 2005 and arrived to the planet in April 2006 where it is now in orbit. Among its scientific payload, the Visible and In…
On the variability of Saturn's equatorial jet at cloud top level
Hueso, R.; Sánchez-Lavega, A.; Pérez-Hoyos, S.
Saturn's Equatorial jet is apparently highly variable in wind speed at the upper cloud level with changes, between 1980-81 and 1994-2004, amounting up to a 40% in its peak value. However, there is some controversy if this is a real change in the winds or an effect due to clouds placed at different altitude levels where a vertical wind shear is pre…