VITRUV - Imaging close environments of stars and galaxies with the VLTI at milli-arcsec resolution

The VITRUV project has the objective to deliver milli-arcsecond spectro-images of the environment of compact sources like young stars, active galaxies and evolved stars to the community. This instrument of the VLTI second generation based on the integrated optics technology is able to combine from 4 to 8 beams from the VLT telescopes. Working primarily in the near infrared, it will provide intermediate to high spectral resolutions and eventually polarization analysis. This paper summarizes the result from the concept study led within the Joint Research Activity advanced instruments of the OPTICON program.Comment: In "The Power of Optical/IR Interferometry: Recent Scientific Results and 2nd Generation VLTI Instrumentation", Allemagne (2005) in pres

VSI: a milli-arcsec spectro-imager for the VLTI

VLTi Spectro-Imager (VSI) is a proposition for a second generation VLTI instrument which is aimed at providing the ESO community with the capability of performing image synthesis at milli-arcsecond angular resolution. VSI provides the VLTI with an instrument able to combine 4 telescopes in a baseline version and optionally up to 6 telescopes in the near-infrared spectral domain with moderate to high spectral resolution. The instrument contains its own fringe tracker in order to relax the constraints onto the VLTI infrastructure. VSI will do imaging at the milli-arcsecond scale with spectral resolution of: a) the close environments of young stars probing the initial conditions for planet formation; b) the surfaces of stars; c) the environment of evolved stars, stellar remnants and stellar winds, and d) the central region of active galactic nuclei and supermassive black holes. The science cases allowed us to specify the astrophysical requirements of the instrument and to define the necessary studies of the science group for phase A.Comment: 12 page

GENIE: High-Resolution Study of Debris Disks

GENIE, the Ground-based European Nulling Interferometer Experiment, will combine the lights collected in the L’ band by two VLT telescopes in a destructive way, thereby revealing the thermal and/or scattered emission of faint objects in the close neighbourhood of the target star. A prime scientific goal for GENIE thus consists in the detection and characterization of debris disks around nearby Vega-type stars. Thanks to its high angular resolution and operating wavelength (3.8 µm), GENIE will be particularly sensitive to the thermal emission from the warm dust standing within a few AU from the star, a part of the disks which is not accessible with current detection methods (IR photometric excesses, sub-millimeter imaging, …). In this paper, we investigate the capabilities of GENIE to detect and characterize the physical parameters of the debris disk around zeta Leporis, a prototypical Vega-type star suspected to harbour a warm dust component in its debris disk (Fajardo-Acosta et al., AJ 115, 2101). This study is then extended to the detection of faint exozodiacal disks around typical Darwin/TPF targets, thereby demonstrating the very high potential of GENIE in the field of high-contrast imaging

Polar-interferometry: what can be learnt from the IOTA/IONIC experiment

We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late-type giants. Optical modeling of the array and dedicated laboratory measures allowed us to confirm the good accuracy obtained on the calibrated polarized visibilities and closure phases. However, no evidences for polarimetric features at high angular resolution have been detected. The simulations and the results presented here open several perspectives for polar-interferometry, especially in the context of fibered, single-mode combiners

A Numerical Simulator for VITRUV

VITRUVsim is a numerical tool with as much as possible physics included. Inputs are the source parameters (flux, morphology, position...) and outputs are sequences of observed fringes and/or reduced visibilities. VITRUVsim is written in a portable and free language

Polar-interferometry: What can be learnt from the IOTA/IONIC experiment

ABSTRACT We report the first near-IR polar-interferometric observations, performed at the IOTA array using its integrated optics combiner IONIC. Fringes have been obtained on calibration stars and resolved late-type giants. Optical modeling of the array and dedicated laboratory measures allowed us to confirm the good accuracy obtained on the calibrated polarized visibilities and closure phases. However, no evidences for polarimetric features at high angular resolution have been detected. The simulations and the results presented here open several perspectives for polar-interferometry, especially in the context of fibered, single-mode combiners

PEGASE: a DARWIN/TPF pathfinder

The space mission PEGASE, proposed to the CNES (Centre National d'Etudes Spatiales = French Space Agency) in the framework of its call for scientific proposals : "formation flying missions", is a 2-aperture interferometer, composed by 3 free flying satellites (2 siderostats and 1 beam combiner), allowing baselines from 50 to 500 m in both nulling and visibility modes. With an angular resolution of a few mas and a spectral resolution of several tens in the spectral range 2.5-5 microns, PEGASE has several goals:science : spectroscopy of hot jupiters (Pegasides) and brown dwarves, exploration of the inner part of protoplanetary diskstechnology : validation in real space conditions of formation flying, nulling and visibility interferometry concepts.PEGASE has been studied at a 0-level. In this paper, we summarize the scientific program and associated technological and mission trade-off coming from this 0-level study. We also discuss how PEGASE can be considered as a TPF/DARWIN pathfinder in an international roadmap towards more complex space interferometry missions such as DARWIN/TPF

PEGASE... towards DARWIN

The space mission PEGASE, proposed to CNES in the framework of its call for scientific proposals on "formation flying", is a 2-aperture interferometer, composed by 3 free flying satellites. With an angular resolution of a few mas and a spectral resolution of several tens in the spectral range 2.5-5 mum, PEGASE has several goals: - science: spectroscopy of hot jupiters (Pegasides) and brown dwarves, exploration of the inner part of protoplanetary disks; - technology: validation in real space conditions of formation flying, nulling and visibility interferometry concepts. PEGASE, presently in 0-phase study takes place in the context of DARWIN preparation. We detail in this paper the present situation of this projec