LERMA UMR8112

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



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LERMA Detailed Presentation

6 April 2020

Administrative team

The administrative team of LERMA is composed of 7 agents who work closely with the administrative services of the CNRS (Ile de France-Meudon delegation (DR5) and INSU), the Paris Observatory (...)

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6 April 2020

Management team

Director: Benoit SEMELIN
benoit.semelin @ obspm.fr
Deputy Director: Martina WIEDNER
martina.wiedner @ obspm.fr
Deputy Director: Ludovic PETITDEMANGE
ludovic.petitdemange @ obspm.fr (...)

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6 April 2020

Organizationals charts

Technical organization chart
Administrative organization chart
Computer organization chart

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6 April 2020

LERMA presentation

LERMA (Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres) is a research entity operated by CNRS and 3 higher education institutions: Observatoire de Paris (OP), (...)

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29 October 2014

Main partners and collaborations

LERMA develope numerous collaborations both national and international
Major agencies and institutions in charge of space missions and major ground-based facilities having collaborations with (...)

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Séminaires à venir

Vendredi 27 novembre 2020, 14h00
via Zoom,
La phosphine sur Vénus : Une histoire brève qui en dit long
Thérèse ENCRENAZ
LESIA, Observatoire de Paris
résumé :
Le 14 septembre 2020, une nouvelle fait sensation dans le monde des astronomes… et au-delà. A partir de données obtenues avec le JCMT et ALMA, une équipe internationale pilotée par Jane Greaves (Université de Cardiff, UK) annonce la détection de la phosphine (PH3) dans l’atmosphère de Vénus et évoque la possibilité d’une forme de vie sur la planète. Plusieurs articles sont publiés ou soumis dans la foulée, étudiant les qualités éventuelles de la phosphine en tant que biomarqueur ou évoquant un développement possible de la vie dans les nuages de Vénus, et la presse internationale en fait grand cas. De notre côté, au LESIA, nous menons depuis huit ans une campagne d’observations de Vénus en infrarouge, avec le télescope IRTF de Maunakea, pour étudier les variations de deux molécules mineures importantes pour la climatologie de Vénus, SO2 et H2O. En mars 2020, nous avons été contactés par l’équipe de J. Greaves pour rechercher la phosphine dans l’infrarouge avec l’instrument que nous utilisons. Les observations n’auront pas lieu à cause de la crise sanitaire. Cependant, nous avons recherché la signature de PH3 dans d’anciennes données infrarouges prises avec le même instrument, et nous en avons déduit pour l’abondance de PH3 une limite supérieure très contraignante, quatre fois plus faible que la valeur annoncée par Jane Greaves et ses collègues. Par ailleurs, le traitement des données ALMA par son équipe fait l’objet de nombreuses réserves ou critiques de la part des radioastronomes. Il est donc vraisemblable que l’engouement des média pour la phosphine de Vénus va retomber prochainement…
 
Vendredi 4 décembre 2020, 14h00
via Zoom,
Simulating galaxies at high resolution in their cosmological context with NewHorizon: methods and some key results on galaxy properties and their morphology
Yohan DUBOIS
Institut d'Astrophysique de Paris
résumé :
Hydrodynamical cosmological simulations are increasing their level of realism by considering more physical processes, having more resolution or larger statistics. However, one usually has to either sacrifice the statistical power of such simulations or the resolution reach within galaxies. I will introduce the NewHorizon project where a zoom-in region of ~(16 Mpc)^3, larger than a standard zoom-in region around a single halo, embedded in a larger box is simulated at high resolution. A resolution of up to 34 pc, typical of individual zoom-in state-of-the-art resimulated halos is reached within galaxies, allowing the simulation to capture the multi-phase nature of the interstellar medium and the clumpy nature of the star formation process in galaxies. I will present and discuss several key fundamental properties of galaxies and of their black holes. Due to its exquisite spatial resolution, NewHorizon captures the inefficient process of star formation in galaxies, which evolve over time from being more turbulent, gas-rich and star-bursting at high redshift. These high redshift galaxies are also more compact, and are more elliptical, disturbed and clumpier until the level of internal gas turbulence decays enough to allow for the formation of stable rotating discs. I will show the origin and persistence of the thin and thick disc components, and explain why the settling of discs ``magically’’ occurs at around a stellar mass of 1e10 Msun.

 
Vendredi 11 décembre 2020, 14h00
via Zoom,
Investigating the physical processes driving the evolution of baryons in local and high-redshift low-metallicity galaxies
Ambra NANNI
Laboratoire d'Astrophysique de Marseille
résumé :
The chemical enrichment in the interstellar medium of galaxies is regulated by several physical processes: stellar birth and death, dust growth and destruction, galactic inflows and outflows. Understanding the interplay of such processes is essential in order to study galaxy evolution, the chemical enrichment of the Universe through the cosmic epochs and to interpret the available and future observations. Despite the importance of such topics, the contribution of different stellar sources to the chemical enrichment of galaxies, e.g. massive stars exploding as Type II supernovae and low-mass stars, as well as the mechanisms driving the evolution of gas, metal and dust grains, remains controversial. In this seminar, I will revise our current knowledge on these physical processes and the observational challenges. I will then present the results of a recent investigation focused on local low-metallicity galaxies for which the evolution of metals, gas and dust content has been studied. In particular, I will show how the comparison between model predictions and observations can allow us to identify the most relevant physical processes determining the chemical evolution of these systems. I will then discuss how the information derived for local low-metallicity galaxies can be employed to study Lyman-Break Galaxies at the epoch of reionization, which are often considered to be their high-redshift counterparts.


 
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