LERMA UMR8112

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



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LERMA presentation

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LERMA (Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres) is a research entity operated by CNRS and 4 higher education institutions : Observatoire de Paris (OP), École normale supérieure (ENS), Université Pierre et Marie Curie (UPMC - Paris 6), and Université de Cergy-Pontoise (UCP). These 4 institutions host the various research groups of LERMA.

Organisation of the laboratory and research topics
LERMA is organized in 4 Research Poles, complemented by 1 transverse structure dedicated to Technology and Research Support. Doctoral studies are principally conducted within École doctorale Astronomie et Astrophysique d’Île de France (ED 127), but about half of our PhD students belong to other doctoral schools in physics, engineering and environment (ED 129, 391, 389, Ed-PIF et 417).

"Galaxies and Cosmology" (OP)

  • Early Universe
  • Galaxy formation and dynamics
  • Clusters of galaxies
  • Dark matter
  • Active galactic nuclei, star formation and feedback in galaxies

"Dynamics of the Interstellar Medium and Stellar Plasmas" (ENS, OP, UPMC)

  • Observational characterization of the ISM cycle
  • Modeling ISM evolution from diffuse gas to stars and disks
  • Chemical diagnostics of ISM dynamics
  • Turbulent and radiative transport in (circum)stellar plasmas
  • Experimental studies of (circum)stellar plasmas

"Molecules in the Universe" (UCP, OP, UPMC)

  • Gas-surface interactions
  • Gas-phase molecular processes
  • Exotic isotopic spin ratios
  • Molecular parameters for planetary, terrestrial atmospheres and ISM

"Instrumentation Terahertz and Remote Sensing" (OP)

  • THz components and subsystems
  • THz heterodyne instruments
  • Characterization of clear, cloudy, and rainy atmospheres
  • Characterization of Earth, planets, and comets
  • Data processing, storage and diffusion

Personnel (as of January 2017)

  • 46 engineers and technicians (including 10 under contract)
  • 10 astronomers (including 2 emeriti)
  • 32 teaching researchers (including 3 emeriti and 3 under contract)
  • 21 researchers (including 7 emeriti) 7 post-doctoral fellows
  • 41 PhD students

Salient results

  • The earliest phase of star formation, captured through its bipolar ejection activity (Gerin et al. 2015 A&A 577, L2). La toute première étape de la formation d’une étoile, révélée par son éjection bipolaire (Gerin et al. 2015 A&A 577, L2).
  • New method for measuring the diffusion and desorption energy of atoms and (Minissale, M., Congiu, E., & Dulieu, F. 2016, A&A, 585 A146). Nouvelle méthode pour mesurer l’énergie de diffusion et de désorption des atomes et radicaux (Minissale, M., Congiu, E., & Dulieu, F. 2016, A&A, 585 A146).
  • First results on a 1200 GHz Schottky receiver prototype for JUICE-SWI (Maestrini, A., et al 2016). Les premiers résultats sur le prototype de récepteur Schottky à 1200 GHz pour JUICE-SWI (Maestrini, A., et al 2016).

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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