LERMA UMR8112

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



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Adresses et accès aux sites du LERMA

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Le LERMA est implanté sur 5 sites en région parisienne :

- à l’Observatoire de Paris (sites de Paris et Meudon)
- à l’Université Pierre et Marie Curie (UPMC)
- à l’ENS
- à l’Université de Cergy Pontoise (UCP)

Site de l’Observatoire de Paris : site de Paris
- Adresse postale : 61, avenue de l’Observatoire -75014 PARIS
- Entrée piétons et véhicules : 77, Avenue Denfert-Rochereau - 75014 Paris
- Standard : +33 1 40 51 22 21 - Fax : +33 1 43 54 18 04
- Accès

Site de Observatoire de Paris : site de Meudon
- Adresse postale et accès piéton : Observatoire de Paris, site de Meudon - 5, place Jules Janssen - 92195 Meudon cedex
- Accès véhicules et livraisons : 11, avenue Marcelin Berthelot - 92195 Meudon
- Standard : +33 1 45 07 75 30
- Accès

Site de l’UPMC
- Adresse postale : UPMC - case courrier 76 - 4 place Jussieu - 75252 Paris cedex 05
- Accès piéton : 4, place Jussieu - 75252 Paris cedex 05
- Accès :

  • Tour 32-33 2ème et 3ème étage
  • Tour 24-34 5ème étage

Site de l’ENS
- Adresse postale : LERMA/L.R.A. - Département de Physique ENS - 24, rue Lhomond - 75231 PARIS Cedex 05
- Accès

Site de Cergy Pontoise
- Adresse postale : LERMA/LAMAP - Site de Neuville II - UFR Sciences et Techniques - Département de physique - 5, mail Gay Lussac - 95031 Cergy-Pontoise cedex
- Accès

Séminaires à venir

Vendredi 21 septembre 2018, 14h00
Salle de l'atelier, Paris
Understanding the structure of molecular clouds: Multi-line wide-field imaging of Orion B
Jan ORKISZ
Iram
résumé :
The new generation of wide-bandwidth high-resolution receivers turns
almost any radio observation into a spectral survey. In the case of
wide-field imaging of the interstellar medium, such a wealth of data
provides new diagnostic tools, but also poses new challenges in terms of
data processing and analysis.

The ORION-B project aims at observing 5 square degrees of the Orion B
molecular cloud, or about half of the cloud's surface, over the entire
3mm band. The emission of tens of molecular tracers have been mapped,
including CO isotopologues, HCO+, CN, HNC, N2H+, methanol, SO, CN...
Machine learning techniques have been applied to these maps, in order to
segment the molecular cloud into typical regions based on their
molecular emission, and to idenfify the most meaningful correlations of
different molecular tracers with each other and with physical quantities
such as density or dust temperature.

The spatial coverage, together with the spatial and spectral resolution,
also allow to characterize statistically the kinematics and dynamics of
the gas. The amount of momentum in the compressive and solenoidal
(rotational) modes of turbulence are retrieved, showing that the cloud
is dominated by solenoidal motions, with the compressive modes being
concentrated in two star-forming regions - which is in line with the
overall very low star formation efficiency of the cloud, and highlights
the role of compressive forcing in the star formation process. The
filamentary network of the molecular cloud also proves to have
particluarly low densities, and is very stable against gravitational
collapse and fragmentation, which also points at a young evolutionary
stage of the filaments.
 
Vendredi 5 octobre 2018, 14h00
Salle de l'atelier, Paris
Astrochemistry in star forming regions : new modeling approaches
Emeric BRON
IRAM/LERMA
résumé :
Star-forming regions present rich infrared and millimeter spectra emitted by the gas exposed to the feedback of young stars. This emission is increasingly used to study the star formation cycle in other galaxies, but results from a complex interplay of physical and chemical processes : chemistry in the gas and on grain surfaces, (de)excitation processes of the atoms and molecules, heating and cooling balance,... Its understanding thus requires detailed astrochemical models that include the couplings between these processes. In this talk, I will present several examples where new modeling approaches of specific processes and their couplings proved crucial to solve persistent observational riddles : from the driving role of UV irradiation in the dynamics of photodissociation regions (PDR) to the efficient reformation of molecular hydrogen in these regions.
 
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