LERMA UMR8112

Laboratoire d’Études du Rayonnement et de la Matière en Astrophysique et Atmosphères



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Molecules in the Universe


Molecules, ubiquitous in our atmosphere and in space, are providing powerful tools for probing the physics and chemistry of many different environments. They provide important clues for major scientific objectives such as climatology and planetology, star and planet formation and the question of the origin of life.


The analysis of molecular radiation under various extreme conditions requires nowadays, a high level of knowledge in molecular science which has to support a wealth of observational data arising from new generation of telescopes, satellites and probes. In addition, molecular processes are at the cornerstone in the evolution of matter in space.

The thematic pole “Molecules in the Universe” aims at pushing forward the current theoretical and experimental limits in molecular science in order :
(1) to obtain fundamental molecular parameters with high degree of accuracy that are essential for probing and modelling complex media and
(2) to understand and predict - at atomic and molecular levels - an increasing number of unknown molecular processes.

This pole brings together research groups leader in quantum physics/chemistry, low temperature physics, chemical physics as well as surface science researchers. It includes complementary theoretical and experimental teams based at Paris (Jussieu Campus), Meudon and Cergy-Pontoise.

The pole aims at playing a major role at the interface between molecular and astrophysics & atmospheric sciences while being fully invested in fundamental molecular and chemical physics science.

This reserach group has long standing experience in multi-disciplinary approaches and is a major actor of “Laboratory Astrophysics” (http://www.labastro.eu/), a new European Networks engaged in fundamental experimental, interpretative and computational research and modelling.
The pole contributes to the establishment and management of widely-used atomic and molecular databases and data centres (http://www.vamdc.eu/).

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Séminaires à venir

Vendredi 14 juin 2019, 14h00
Salle de l'atelier, Paris
Astronomie au Pôle Sud en 1984 : la mission EMILIE
Jean-Michel LAMARRE
Observatoire de Paris/LERMA
résumé :
En 1984 une équipe du CNRS soutenue par l’INAG (INSU aujourd’hui), en association avec l’Université du Delaware et l’appui du programme antarctique des USA, a installé l’expérience EMILIE pour quelques semaines au Pôle Sud géographique pour y effectuer les premières observations astronomiques en ondes submillimétriques. Les conditions d’altitude et de température font du Pôle Sud un site unique pour ce domaine spectral, mais les conditions d’accès en sont particulièrement difficiles et les questions logistiques y occupent une place vitale, au sens propre.

Le récit de ces premières observations sera replacé dans ce contexte particulier et dans le cadre géographique exceptionnel de ce continent. On s’appuiera pour cela sur les cahiers de manip et sur des photos de la mission, mais on ne se privera pas d’utiliser les images les plus spectaculaires et les données les plus récentes de la recherche polaire, ni d’ailleurs celles de "l’âge héroïque" de l’exploration de l’Antarctique.

L’expérience EMILIE fut pour ses participants une étape importante du long apprentissage technique et scientifique qui a donné naissance au satellite Planck. On doit aussi y voir les prémices de l’observatoire submillimétrique aujourd’hui en activité au Pôle Sud, le « dark sector » de la station Amundsen-Scott.


 
Vendredi 21 juin 2019, 14h00
Salle de l'atelier, Paris
Accretion-driven turbulence and observational signatures
Pierre GUILLARD
IAP
 
Vendredi 5 juillet 2019, 14h00
Salle de l'atelier, Paris
Self-generated UV in molecular shocks
Andrew LEHMANN
ENS
 
Vendredi 20 septembre 2019, 14h00
----------, Paris
Challenging a Newtonian prediction through Gaia wide binaries
Xavier HERNANDEZ
UNAM, Mexico
résumé :
Under Newtonian dynamics, the relative motion of the components of a binary star should follow a Keplerian scaling with separation. Once orientation effects and a distribution of ellipticities are accounted for, dynamical evolution can be modelled to include the effects of Galactic tides and stellar mass perturbers. This furnishes a prediction for the relative velocity between the components of a binary and their projected separation. After reviewing recent work evidencing the existence of a critical acceleration scale in Elliptical Galaxies and Globular Clusters, I will show new results showing such a phenomenology in Gaia wide binaries using the latest and most accurate astrometry available. The results are consistent with the Newtonian prediction for projected separations below 7000 AU, but inconsistent with it at larger separations, where accelerations are expected to be lower than the critical a0 value of MONDian gravity. This result challenges Newtonian gravity at low accelerations and shows clearly the appearance of gravitational anomalies of the type usually attributed to dark matter at galactic scales, now at much smaller stellar scales.


 
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