Paris Astronomical Data Centre

Observatoire de Paris


Theoretical services

The state-of-the-art in numerical simulations is defined by codes that have been developed and refined over decades. It is recognized that a scientific return of large instruments will only be achieved if the community has access to these codes to prepare missions and to interpret observations.

In this context, VO-Theory activities at VO-Paris cover a wide range of activities to provide theoretical services to the community. This includes the «Interstellar medium & Jets services» that gather services related to astrochemistry and MHD simulations to interpret observations, DEUVO, a diffusion service of large simulations in cosmology and GalMer, a service providing galaxy mergers simulations.

VO-Paris participates to the development of VO standards at the IVOA.

Interstellar Medium & Jets services

Interstellar Medium & Jets services gather a set of theoretical services based on state-of-the-art numerical models. The goal of the service is to provide to the community all the required numerical models to interpret spectroscopic observations in atomic and molecular gas in galactic and extragalactic environments. It is mainly focused on astro-chemistry and radiative transfer codes as well as MHD simulations of dense cores, jets, etc.

This is an INSU / SO5 service developed and maintained by CEA and VO-Paris DataCentre. Euro-VO DCA and Aïda as well as ASTRONET have supported some parts of the development. These services are used as implementation validators of VO-Theory standards at the IVOA.

Related services are:

PDR services
The Meudon PDR code computes the atomic and molecular structure of interstellar clouds. It provides line intensities, column densities and cloud structure (chemical abundances, excitations, temperatures...) that can be compared to observations. Implemented physics is relevant for diffuse clouds, photo-dissociation regions, star forming regions, dark clouds, ... in galactic and extragalactic media. It is used to prepare and interpret observations from far-UV to sub-mm (FUSE, HST/STIS, ISO, Spitzer, Herschel, PdBI / Noema, ALMA, ...)
The code is developed and maintained since more than 10 years at Paris Observatory.
The service provides:
  • access to the Meudon PDR code
  • a database of pre-computed models with tools to discover them and extract data
  • help to users
  • specific chemistry and physics implementations if required by users
Paris-Durham Shock code
The Paris-Durham Shock code computes the temperature and chemical abundances in galactic and extragalactic shocks. It resolves the dynamical structure of the gas (density, temperature and velocity of its components), as well as the chemistry for over 125 species linked by more than 1000 reactions. These data can be post-processed by an LVG radiative transfer code to compute line intensities. The service is dedicated to the preparation and the interpretation of observations in jets and bipolar outflows associated to low-mass forming stars, shocks associated to supernovae remnants.
The service gives access to:
  • an online version of the Paris-Durham shock code
  • help to users
The STARFORMAT database gives access to heavy MHD numerical simulations computed in order to study the problem of star formation, essentially molecular cloud formation, evolution and collapse.
Understanding the dynamical evolution of the interstellar medium (ISM) and its relation to stellar birth is a key challenge in astronomy and astrophysics. The StarFormat project aims at providing observers and theorists studying formation and evolution of molecular clouds, their morphological and kinematical characteristics, and the formation of stars in their interior with a set of theoretical tools and a database of models to aid in the analysis and interpretation of current and future observations. Data cubes can be post-processed by the 3D radiative transfer code (RADMC-3D).
The goal of this database is to give access to observers, or more generally to any scientist working on a related field, to the results of these numerical simulations, which could be useful to prepare or analyze observations.

Future services (in development)

Several other services are in development. Next services that will be available to the community are an ALMA simulator to prepare observations, online radiative transfer codes and services about the modeling of turbulence and its impact on chemical abundances.


The goal of the DEUS project (Dark Energy Universe Simulation) is to investigate the imprints of dark energy on cosmic structure formation through high-performance numerical simulations. DEUVO service gives access to catalogs of hundreds of millions of halos and hundreds of thousands of cosmological fields together with their properties for several cosmological models and times. Halos mass ranges from one hundredth of Milky Way mass to the one of the most massive cluster of the observable universe. DEUVO also gives access to dark matter particles within fields and halos. Halos and fields have been extracted from DEUS and DEUS FUR Grand Challenge simulations. These simulations have been run using AMADEUS application on French and European super-computers (Babel/Curie). DEUSS allows to probe a range of scales from one tenth of Milky Way diameter up to a fraction of the horizon while DEUS FUR is the first simulation of the whole observable universe with 500 billions of dark matter particles. Data can be downloaded and visualized in TOPCAT.


GalMer is a database of simulations of galaxies (isolated, interaction, mergers). The goal is to provide to the community a tool to interpret observations and to identify the main physical processes of galaxies formation and evolution. Simulations have been produced by means of a Tree-SPH code. Star formation and metal enrichment are modeled by means of a hybrid particles scheme. The service provides access to visualization of 2D and 3D data, animations, production of maps, stellar populations distributions and spectra (Pegase-HR). New simulations are regularly added to the database.

Preview images and their manipulation can be done thanks to VO software such as TOPCAT, CDS Aladin, ESA VOSpec.