Search results for "Huygens"
showing 9 items of 9 documents
Applications of a new set of methane line parameters to the modeling of Titan's spectrum in the 1.58 μm window
2012
International audience; In this paper we apply a recently released set of methane line parameters (Wang et al., 2011) to the modeling of Titan spectra in the 1.58 mu m window at both low and high spectral resolution. We first compare the methane absorption based on this new set of methane data to that calculated from the methane absorption coefficients derived in situ from DISR/Huygens (Tomasko et al., 2008a; Karkoschka and Tomasko, 2010) and from the band models of Irwin et al. (2006) and Karkoschka and Tomasko (2010). The Irwin et al. (2006) band model clearly underestimates the absorption in the window at temperature-pressure conditions representative of Titan's troposphere, while the Ka…
The 2-μm spectroscopy of Huygens probe landing site on Titan with Very Large Telescope/Nasmyth Adaptive Optics System Near-Infrared Imager and Spectr…
2007
[1] Several ground-based telescopes followed the event of the Huygens probe descent through Titan's atmosphere (14 January 2005). We used the Nasmyth Adaptive Optics System Near-Infrared Imager and Spectrograph (NACO) adaptive optics system at the UT-4 of the Very Large Telescope in Chile to perform both spectroscopic and imaging measurements of Titan. We present here a selected sample of the spectra we acquired on 16 January 2005 in the K band between 2.03 and 2.40 μm. Our spectra include the Huygens landing site and surrounding dark and bright areas. We apply a radiative transfer code using new methane absorption coefficients calculated in the 2-μm region. The analysis of the data yields …
La découverte de l'anneau de Saturne par Huygens
1907
Zvaigžņotā Debess: 2005, Pavasaris
2005
Contents: A.Balklavs, N.Cimahoviča, J.Ikaunieks. Radio Astronomy in the Baltic Republics ; L.Maistrovs. Keeping Watch on Precision ; A.Balklavs. The Anthropic Principle ; Z.Alksne, A.Alksnis. Has Exoplanet Been Spotted at Last? ; J.Freimanis. The Distance to Pleiades and Problems with Hipparcos ; A.Balklavs. Does the Chandra See Black Holes in Distant Galaxy? ; A.Balklavs. Massive Black Holes – Remnants of the First Stars’ Evolution ; A.Balklavs. Cosmic Objects in Captivating Photos – 4 ; M.Gills. A Collision or a Unique Event? ; J.Jaunbergs. Volcanological Safari of Io ; D.Krieviņš. Space Launchers of Early XXI Century. Europe, Japan, China and other States ; M.Sudārs. Huygens Landing on t…
Huygens: lost – regained – revised. De literair-historische receptie van Constantijn Huygens in de eerste helft van de 19e eeuw
2018
Huygens: lost ‒ regained ‒ revised. De literair-historische receptievan Constantijn Huygens in de eerste helftvan de 19e eeuwFrom the beginning of professional Dutch Studies M. Siegenbeek’s inauguration as professor eloquentiae hollandicae extraordinarius, 1797 the 17th century Dutch writers P.C. Hooft and Joost van den Vondel are present in Dutch literary studies and literary historiography. The position of ConstantijnHuygens, whom the contemporary literary scholars also include in the Grote Vijf Great Five of the 17th-century Dutch literature besides Vondel, Hooft, Cats and Bredero, was gradually changing during the 19th century. This article postulates that the reception of Huygens in …
Focal switch: a new effect in low-Fresnel-number systems
2010
It is shown for the first time we believe, that when a spherical wave illuminates a certain type of diffracting screen, in addition to the expected focal-shift effect, depending on the value of the Fresnel number of the focusing system, a focal switch effect can appear, i.e., an increase in the height of the lateral lobe of the axial-intensity distribution over that of the central lobe.
Scattering on Riemannian Symmetric Spaces and Huygens Principle
2018
International audience; The famous paper by L. D. Faddeev and B. S. Pavlov (1972) on automorphic wave equation explored a highly romantic link between Scattering Theory (in the sense of Lax and Phillips) and Riemann hypothesis. An attempt to generalize this approach to general semisimple Lie groups leads to an interesting evolution system with multidimensional time explored by the author in 1976. In the present paper, we compare this system with a simpler one defined for zero curvature symmetric spaces and show that the Huygens principle for this system in the curved space holds if and only if it holds in the zero curvature limit.
Off-axis focal shift for rotationally nonsymmetric screens
2009
We report on an analytical formulation for evaluating the amplitude distribution along any line directed toward the geometrical focus of a spherical wave front that passes through a rotationally nonsymmetric diffracting screen. Our formula consists of two factors. The first factor involves the one-dimensional Fourier transform of the projection of the screen function onto the off-axis line. The second factor depends on the inverse distance to the screen and permits us to recognize the existence of focal shift along off-axis lines.
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2006
Resumen basado en el de la publicación Resumen en inglés Se muestra el importante papel de uno de los instrumentos más comunes, el péndulo, en la construcción del paradigma newtoniano. Del análisis de algunas aplicaciones interesantes llevadas a cabo por los mejores científicos de ese tiempo, se concluye que el uso apropiado del péndulo en el aula puede ser una manera fácil de introducir la evolución histórica y epistemológica de conceptos físicos básicos. ESP