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 décembre 2018, 14h00
Salle de l'atelier, Paris
Astrochemistry in star forming regions : new modeling approaches
Emeric BRON
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.
 
Mardi 15 janvier 2019, 11h00
Salle de l'atelier, Paris
ATTENTION jour ET heure inhabituels
Thresholds for Globular Cluster Formation and their Dominance of Star Formation in the Early-Universe
Bruce ELMEGREEN
IBM Research Division
résumé :
Young massive clusters (YMCs) are usually accompanied by lower-mass clusters and unbound stars with a total mass equal to several tens times the mass of the YMC. If this was also true when globular clusters (GCs) formed, then their cosmic density implies that most star formation before redshift ~2 made a GC that lasted until today. Star-forming regions had to change after this time for the modern universe to be making very few YMCs. Here we consider the conditions needed for the formation of a ~10^6 Msun cluster. These include a star formation rate inside each independent region that exceeds ~1 Msun/yr to sample the cluster mass function up to such a high mass, and a star formation rate per unit area of Sigma_SFR ~ 1 Msun/kpc^2/yr to get the required high gas surface density from the Kennicutt-Schmidt relation, and therefore the required high pressure from the weight of the gas. High pressures are implied by the virial theorem at cluster densities. The ratio of these two quantities gives the area of a GC-forming region, ~1 kpc^2, and the young stellar mass converted to a cloud mass gives the typical gas surface density of 500-1000 Msun/pc^2. Observations of star-forming clumps in young galaxies are consistent with these numbers, suggesting they formed today's GCs. Observations of the cluster cut-off mass in local galaxies agree with the maximum mass calculated from Sigma_SFR. Metal-poor stellar populations in local dwarf irregular galaxies confirm the dominant role of GC formation in building their young disks.
 
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