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Analysis and Modeling at High Angular Resolution

Principal investigator: Armando Domiciano

AMHRA develops and provides online astrophysical models and data analysis tools dedicated to the scientific exploitation of high angular and high spectral facilities such as ESO-VLTI. It is aimed at users seeking to prepare, model, and analyze interferometric observations, notably those from the second generation of VLTI instruments, GRAVITY and MATISSE, with unprecedented capabilities on high spectral and spatial resolution.

VLT interferometric array


AMHRA provides:

  • Polychromatic images from astrophysical models with fast computation time (real time models)
  • Polychromatic images from a precalculated grid of astrophysical models
  • Spectro-interferometric observables from model images (OIFits modeler)
  • Analysis and model-fitting tools for spectro-interferometry

This service was initially published under the name “Analyse et Modélisation en Haute Résolution Angulaire”.

AMHRA is a working group of MOIO/JMMC and is supported by the Observatoire de la Côte d'Azur (OCA) through the DOMINO expertise center. MOIO is a French AA-ANO5 SNO supported by CNRS-INSU.

Real time astrophysical models

Kinematic be disk
Kinematic Be disk

Model of the geometry (size and shape) and kinematics (rotation and expansion) of circumstellar, flat, rotating disks, relevant to Be stars. It is suited to interpret spectro-interferometric data obtained on emission lines formed in the disk.

Disk and stellar continuum – DISCO

Model of the continuum emission from a star surrounded by a gaseous circumstellar disk (free-free and bound-free), with partially ionized and geometrically thin disk with a physical structure given by the viscous Keplerian decretion disk model. DISCO is well suited to model Be stars.

Binary spiral model

Phenomenological model mimicking the shock caused by the collision between the winds from massive stars (e.g. WR and OB stars) and that results in dusty spirals.

Analytical Limb-darkening Elliptical or Spherical – ALDES

ALDES provides intensity maps (images) or 1d intensity profiles for spherical or elliptical stars showing the limb darkening (LD) effect. Different LD laws are offered: uniform disk, linear, power law, quadratic, square root, logarithmic and four-parameter.

Simple YSO model
Simple YSO model – sYSOm

Model of the continuum emission from a young stellar object (YSO) composed by a central star, modeled as a blackbody, and a dusty circumstellar disk. The disk is assumed to be geometrically flat with radial-dependent temperature and surface density prescribed by power laws.

Precalculated grids of astrophysical models

Supergiant B[e] with HDUST

Grid of models for B[e] supergiant stars computed with the 3d Monte Carlo radiative transfer code HDUST. The non-spherical circumstellar envelope (CSE), composed of gas (hydrogen) and dust (silicate), is modelled considering a bimodal outflow description (two-component wind).

Limb-darkening with SAtlas

Grid of models providing intensity maps for spherically symmetric stars, showing the limb darkening effect. The models were computed with the SAtlas model stellar atmospheres for several spectral bands. Data is provided for FGK dwarfs and red giants.

Analysis and model fitting tools

OIFits modeler

This tool compares real interferometric observations to observables (squared visibilities, closure phases...) calculated by ASPRO routines from a user-provided image (intensity map). Images from AMHRA models or other user-provided images can be used.