Search results for " vela"
showing 10 items of 24 documents
X-raying the interstellar medium: the study of SNR shells at the OAPa
2006
A High-resolution Survey of the physical and chemical Inhomogeneities in the Vela SNR
2007
Hydrodynamic modeling of ejecta shrapnels in the Vela SNR
2008
Conferma della presenza di Isoëtes velata A. Braun (Isoëtaceae, Lycopodiophyta) nella Sicilia occidentale
2010
Indications of a Si-rich bilateral jet of ejecta in the Vela SNR observed with XMM-Newton
2017
Context. The Vela supernova remnant displays several ejecta, which are fragment-like features protruding beyond the front of its primary blast shock wave. They appear to be "shrapnel", bowshock-shaped relics of the supernova explosion. One of these pieces of shrapnel (A), located in the northeastern edge of the remnant, is peculiar because its X-ray spectrum exhibits a high Si abundance, in contrast to the other observed ejecta fragments, which show enhanced O, Ne, and Mg abundances. Aims. In this Letter we present the analysis of another ejecta fragment located opposite to shrapnel A with respect to the center of the shell, in the southwestern boundary of the remnant, named shrapnel G. We …
The Gaia-ESO survey: Discovery of a spatially extended low-mass population in the Vela OB2 association
2015
The nearby (distance~350-400 pc), rich Vela OB2 association, includes $\gamma^2$ Velorum, one of the most massive binaries in the solar neighbourhood and an excellent laboratory for investigating the formation and early evolution of young clusters. Recent Gaia-ESO survey observations have led to the discovery of two kinematically distinct populations in the young (10-15 Myr) cluster immediately surrounding $\gamma^2$ Velorum. Here we analyse the results of Gaia-ESO survey observations of NGC 2547, a 35 Myr cluster located two degrees south of $\gamma^2$ Velorum. The radial velocity distribution of lithium-rich pre-main sequence stars shows a secondary population that is kinematically distin…
Micromorphological approach to the systematics of Mediterranean Isoëtes species (Isoëtaceae, Lycopodiophyta): analysis of the megaspore surface
2012
Megaspore ornamentation is one of the few morphological characters used in the taxonomy of the genus Isoëtes. In the present work, we test the application of this character for distinguishing some Isoëtes species occurring in the Mediterranean: Isoëtes sicula, which according to some authors should be included as a variety in I. histrix, and the recently described I. todaroana, whose affinity with other taxa is currently unknown. Two additional species (I. duriei, I. velata) were also included in the analysis. The megaspores were studied using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy and chemical treatment. In all species, the megaspore surface is cove…
Morfologia verbal catalana: anàlisi diacrònica dels verbs velaritzats
2021
Aquesta tesi té com a objectiu principal estudiar el procés de velarització dins de la flexió verbal catalana des d’un punt de vista diacrònic. Partint dels principis de la morfologia natural i de la morfologia autònoma, es pretén donar compte de la velarització a) del patró L, format per la primera persona del present d’indicatiu i totes les persones del present de subjuntiu; b) del patró PyTA, format pel passat simple, l’antic condicional en -ra i l’imperfet de subjuntiu, i c) dels participis. Per tal de justificar l’extensió de la velar a contextos en què no apareixia inicialment, es fa servir el concepte d’exaptació, que considerem com una reanàlisi no previsible per la gramàtica: l’ext…
L'anfiteatro di Sabratha: vecchie indagini e nuove ricerche
2012
L’Anfiteatro di Sabratha, ignorato dai viaggiatori del XVIII e XIX secolo, venne segnalato nel 1912 da Henri Méhier de Mathuisieulx ed indagato da Renato Bartoccini a partire dal 1924. Gli scavi e le ricerche portate avanti in quegli anni permisero di rimettere in luce gran parte del monumento, che rimase tuttavia non pubblicato. Recenti scavi e ricerche hanno adesso permesso di redigere un nuovo rilievo ed un nuovo studio del monumento. Il grande edificio, realizzato in conci di calcarenite locale, venne costruito sfruttando una cava di pietra alla periferia orientale della città antica probabilmente alla metà circa del II secolo d.C. e, contrariamente a quanto finora ritenuto, venne effet…
Le origini dell’emigrazione dalle Isole Eolie
2015
lo studio mostra come la prima emigrazione dalle isole Eolie non è interpretabile con il modello espulsivo ma obbedisce alle regole dell'attrazione veicolata dai marinai eoliani assunti dalle grandi compagnie di navigazione a vela sin dalla prima metà dell'ottocento.