M. Karam Ouharou

Forty years ago it was proposed that gas phase organic chemistry in the interstellar medium can be initiated by the methyl cation CH 3 +  ( 1–3 ), but hitherto it has not been observed outside the Solar System ( 4, 5 ). Alternative routes involving processes on grain surfaces have been invoked ( 6, 7 ). Here we report JWST observations of CH+3CH3+ in a protoplanetary disk in the Orion star forming region. We find that gas-phase organic chemistry is activated by UV irradiation. Introduction : In the realm of cosmic evolution, protoplanetary disks serve as the cradles of new star systems and planetary bodies. These disks, composed of gas and dust, harbor an intricate web of chemical reactions that sculpt the materials essential for planet formation. Among the diverse array of chemical species within these disks, the methyl cation (CH3+) stands out as a key molecular fragment. Recent research has shed light on the intriguing formation of the methyl cation through photochem...

Il désigne un  modèle cosmologique  dont l'idée principale est que notre univers, et tout ce qu'il contient, serait emprisonné dans une structure appelée  brane  (une « D3-brane » plus exactement), laquelle serait incluse dans un « super-univers » doté de  dimensions supplémentaires  et qui pourrait abriter d’autres branes .  Dans les modèles de compactification à la Kaluza-Klein, on retrouve également une géométrie totale possédant des dimensions supplémentaires mais dont seules quatre sont effectivement visibles. Cependant dans un modèle de compactification, aucun mécanisme de confinement des particules du modèle standard n'est envisagé ce qui impose donc que ces dernières soient compactes et de très petite taille afin d'être compatibles avec les données expérimentales qui sont extrêmement précises (cf mesure de la constante gyromagnétique) et imposent donc une physique des particules quadri-dimensionnelle. Malheure...

A powerful cosmic force that can push interstellar dust clouds of low density into intergalactic space. Although it easily pushes low density gas and dust clouds, it cannot easily push high density clouds. As the cosmic winds start to push the clouds, they start to separate and start looking like taffy being pulled apart.It has a primary composition of photons ejected from large stars and sometimes thermal energy from exploding stars. It can be caused by orbital motion of gas in the cluster of a galaxy, or can be ejected from a black hole. Because new stars and planets form from gases, the cosmic winds that push the gases away are preventing new stars from forming . © Karam OUHAROU. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author. Nous sommes ravis d'améliorer notre service pour vous! © 2014 — 2...

The orbits of objects such as globular clusters and satellite galaxies carry them through the extended dark matter halo (dark halo) and sometimes the dense central regions of their host galaxies. As a satellite moves through this ‘sea’ of stars and dark matter, it experiences a drag which slows it down. This drag is referred to as dynamical friction. The drag results from the satellite accelerating stars and dark matter in its wake – thus increasing their energy and momentum. As a consequence of the conservation of energy and momentum, the satellite itself must therefore lose energy/momentum and slow down. Over time, this causes the satellite to spiral in towards the centre of the host galaxy. This is one of the main driving mechanisms for minor mergers. The dynamical friction experienced by a satellite depends on: Mass – Massive satellites have greater effect on their surroundings and therefore feel a greater dynamical friction. Density...