AMBER, the near-infrared spectro-interferometric three-telescope VLTI instrument (original) (raw)
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AMBER: a near infrared focal instrument for the VLTI
Comptes Rendus de l'Académie des Sciences - Series IV - Physics, 2001
AMBER est l' instruments focal proche infra rouge du mode interférométrique du Très Grand Télescope Européen. Les spécifications de cet instrument généraliste ont été définies pour trois programmes clefs sur les systèmes stellaires en formation, les régions centrales des noyaux actifs de galaxies et les masses et les spectres de planètes extra solaires géantes chaudes. Il combine trois faisceaux, ce qui lui donne une capacité de reconstruction d' images, et est optimisé pour la précision des mesures grâce à un filtrage spatial des faisceaux par des fibres optiques mono mode et à une combinaison des informations obtenues simultanément à différentes longueurs d' onde.
AMBER, the VLTI Near-Infrared Instrument: Design, Status and Scientific Applications
2000
AMBER is the near-infrared instrument being built for the VLT Interferometer by a consortium of several institutes in France, Germany and Italy. Its key characteristics include: the ability to combine two or three beams, allowing closure phase; a wavelength range that initially will cover the near-infrared from 1 to 2.4 µm, possibly to be extended later towards shorter and longer wavelengths as well; variable spectral resolution up to ≈10 4 ; the potential for high accuracy visibility measurements, thanks to a fiber-based beam combination scheme. We review the concept and design of the instrument, implementation schedule and predicted performance. Thanks to the large photongathering power and multiple baselines of the VLTI, AMBER will permit to observe a wide range of sources. We review its application in some key areas of research which will include: hot exoplanets, young stars, AGB and late-type giant stars, binary stars, hot luminous stars, AGN and extragalactic sources.
Optical configuration and analysis of the AMBER/VLTI instrument
Astronomy and Astrophysics, 2007
Aims. This paper describes the design goals and engineering efforts that led to the realization of AMBER (Astronomical Multi BEam combineR) and to the achievement of its present performance. Methods. On the basis of the general instrumental concept, AMBER was decomposed into modules whose functions and detailed characteristics are given. Emphasis is put on the spatial filtering system, a key element of the instrument. We established a budget for transmission and contrast degradation through the different modules, and made the detailed optical design. The latter confirmed the overall performance of the instrument and defined the exact implementation of the AMBER optics. Results. The performance was assessed with laboratory measurements and commissionings at the VLTI, in terms of spectral coverage and resolution, instrumental contrast higher than 0.80, minimum magnitude of 11 in K, absolute visibility accuracy of 1%, and differential phase stability of 10 −3 rad over one minute.
First astrophysical results from AMBER/VLTI
2006
The AMBER instrument installed at the Very Large Telescope (VLT) combines three beams from as many telescopes to produce spectrally dispersed fringes with milli-arcsecond angular scales in the near infrared. Two years after installation, first scientific observations have been carried out during the Science Demonstration Time and the Guaranteed Time mostly on bright sources due to some VLTI limitations. In this paper, we review these first astrophysical results and we show which types of completely new information is made available by AMBER.
Optical and Infrared Interferometry, 2008
The current results of our ongoing Galactic Center (GC) observations with optical long baseline interferometry (OLB-IF) are presented. We achieved first IR-IF fringes in both available IR science regimes of the VLTI (MIDI: 10 µm) and (AMBER: 2 µm), demonstrating the new capabilities provided by large aperture telescope arrays to the Galactic center research. We show that the highest angular resolution only available through interferometric techniques is necessary to observe the GC ISM production in the making and distinguish individual sources from its dusty surroundings. An overview over the currently available IF-technology is given, biased towards the GC science case. The feasibility of phase-referencing to the supergiant GCIRS 7, located only 5 away from SgrA*, to increase the sensitivity and spectral resolution of the observations, is discussed, and supported by the first real data. The presentation will conclude with an outlook to the near future about how the upcoming astrometric and off-axis phase-referencing capabilities of the Keck and VLT Interferometers, nicknamed ASTRA and PRIMA, will greatly extend the currently existing capabilities to observe astrophysical phenomena in the Galactic center at the borderline to General relativity in a yet uninvestigated regime. Telephone: 1 808 881 3543 * VLT Interferometer: http://www.eso.org/projects/vlti/, in this article we consider the array of 8m-UT's as VLTI, since currently the VLTI-AT's are not sensitive enough for GC observations. † http://planetquest.jpl.nasa.gov/Keck/keck index.cfm
2007
Context. Interferometry can provide spatially resolved observations of massive star binary systems and their colliding winds, which thus far have been studied mostly with spatially unresolved observations. Aims. We present the first AMBER/VLTI observations, taken at orbital phase 0.32, of the Wolf-Rayet and O (WR+O) star binary system γ2 Velorum and use the interferometric observables to constrain its properties. Methods. The AMBER/VLTI instrument was used with the telescopes UT2, UT3, and UT4 on baselines ranging from 46 m to 85 m. It delivered spectrally dispersed visibilities, as well as differential and closure phases, with a resolution R = 1500 in the spectral band 1.95−2.17 μm. We interpret these data in the context of a binary system with unresolved components, neglecting in a first approximation the wind-wind collision zone flux contribution. Results. Using WRand O-star synthetic spectra, we show that the AMBER/VLTI observables result primarily from the contribution of the i...
Astronomy and Astrophysics, 2007
Aims. We present the first NIR spectro-interferometry of the LBV η Carinae. The observations were performed with the AMBER instrument of the ESO Very Large Telescope Interferometer (VLTI) using baselines from 42 to 89 m. The aim of this work is to study the wavelength dependence of η Car's optically thick wind region with a high spatial resolution of 5 mas (11 AU) and high spectral resolution. Methods. The observations were carried out with three 8.2 m Unit Telescopes in the K-band. The raw data are spectrally dispersed interferograms obtained with spectral resolutions of 1500 (MR-K mode) and 12 000 (HR-K mode). The MR-K observations were performed in the wavelength range around both the He i 2.059 µm and the Brγ 2.166 µm emission lines, the HR-K observations only in the Brγ line region.