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



by nicolas.moreau@obspm.fr - published on , updated on


Virtual Atomic and Molecular Data Centre Consortium

The "Virtual Atomic and Molecular Data Centre Consortium" (VAMDC Consortium) is a worldwide consortium which federates Atomic and Molecular databases through an e-science infrastructure and an organisation to support this activity (http://www.vamdc.org/structure/how-to-join-us/).

About 90% of the inter-connected databases handle data that are used for the interpretation of astronomical spectra and for the modeling in media of many fields of astrophysics. The VAMDC Consortium has connected databases from other fields such as the radiation damage and the plasma communities.

The infrastructure is composed of several key components :

  • The Portal is a central access point to look for data. It provides a graphical user interface where users can build queries that are distributed to all the relevant databases at the same time.
  • The species database is a repository of all the atomic and molecular species available in VAMDC. It is populated by gathering daily the chemical species available from each database composing the infrastructure. The species database provides a fast and convenient way to discover where data are located.
  • Each database in the infrastructure is queryable through a web service. They are registered in the VAMDC registry

As a major actor in the field of atomic and molecular physics, the LERMA laboratory is a central element in both the governance and the technical maintenance and evolution of the infrastructure. A team of a senior astronomer and 3 software engineers is involved on different aspects :

  • Marie-Lise Dubernet Tuckey (Astronomer) : current chair of the board of director, scientific coordination.
  • Yaye Awa Ba (computer engineer) : development of the Spectcol software and the Basecol VAMDC node, web manager of the VAMDC website
  • Nicolas Moreau (computer engineer) : development of the VAMDC portal and species database, evolution of standards (convergence with IVOA standards), interface with node managers, co-chair of the technical board
  • Carlo-Maria Zwolf (computer engineer ) : executive director of VAMDC, development of the VAMDC querystore, co-chair of Group of European Data Experts in the Research Data Alliance (RDA) and co-chair of the Federation Identity Management Interest Group in the RDA

Séminaires à venir

Vendredi 27 novembre 2020, 14h00
via Zoom,
La phosphine sur Vénus : Une histoire brève qui en dit long
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
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
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 such processes and their relative importance is essential in order to study galaxy evolution and their chemical enrichment 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 remain 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 metal, gas and dust content have been constrained from observations. In particular, I will show how the comparison with model predictions can allow us to identify the most relevant physical processes determining the evolution of these systems. I will finally discuss how the information derived for local low-metallicity galaxies can be used to study Lyman-Break Galaxies at the epoch of reionization, which are often considered to be their high-redshift counterparts.
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