Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements
Context. The variety of physical processes at play in chemically peculiar stars makes it difficult to determine their fundamental parameters. In particular, for the magnetic ones, called Ap stars, the strong magnetic fields and the induced spotted stellar surfaces may lead to biased effective temperatures when these values are derived through spectro-photometry. <BR /> Aims: […]
Calibrating the surface brightness – color relation for late-type red giants stars in the visible domain using VEGA/CHARA interferometric observations
Context. The surface brightness – color relationship (SBCR) is a poweful tool for determining the angular diameter of stars from photometry. It was for instance used to derive the distance of eclipsing binaries in the Large Magellanic Cloud (LMC), which led to its distance determination with an accuracy of 1%. <BR /> Aims: We calibrate […]
Visible and near-infrared spectro-interferometric analysis of the edge-on Be star o Aquarii
<BR /> Aims: We present a detailed visible and near-infrared spectro-interferometric analysis of the Be-shell star o Aquarii from quasi-contemporaneous CHARA/VEGA and VLTI/AMBER observations. <BR /> Methods: We analyzed spectro-interferometric data in the Hα (VEGA) and Brγ (AMBER) lines using models of increasing complexity: simple geometric models, kinematic models, and radiative transfer models computed with […]
A catalogue of stellar diameters and fluxes for mid-infrared interferometry
We present the Mid-infrared stellar Diameters and Fluxes compilation Catalogue (MDFC) dedicated to long-baseline interferometry at mid-infrared wavelengths (3-13 μm). It gathers data for half a million stars, i.e. nearly all the stars of the Hipparcos-Tycho catalogue whose spectral type is reported in the SIMBAD data base. We cross-match 26 data bases to provide basic […]
Bringing the New Adaptive Optics Module for Interferometry (NAOMI) into Operation
NAOMI was developed by a consortium composed of IPAG and ESO. Its Provisional Acceptance Chile review was held in April 2019. The NAOMI systems that have been installed on the Auxiliary Telescopes make the Very Large Telescope Interferometer (VLTI) and its instruments much less dependent on the atmospheric and dome seeing conditions. NAOMI increases the […]
NAOMI: the adaptive optics system of the Auxiliary Telescopes of the VLTI
Context. The tip-tilt stabilisation system of the 1.8 m Auxiliary Telescopes of the Very Large Telescope Interferometer was never dimensioned for robust fringe tracking, except when atmospheric seeing conditions are excellent. <BR /> Aims: Increasing the level of wavefront correction at the telescopes is expected to improve the coupling into the single-mode fibres of the […]
Spectro-interferometric observations of a sample of Be stars. Setting limits to the geometry and kinematics of stable Be disks
Context. Be stars are rapid rotators surrounded by a gaseous disk envelope whose origin is still under debate. This envelope is responsible for observed emission lines and large infrared excess. <BR /> Aims: To progress in the understanding of the physical processes involved in the disk formation, we estimate the disk parameters for a sample […]
Perspectives of a visible instrument on the VLTI
In this paper we present the most promising science cases for a new generation visible instrument on the VLTI and the conceptual idea for the instrumental configuration. We also present a statistical study of the potential targets that may be accessible for the different classes of objects and for the required spectral resolutions.
Fibered visible interferometry and adaptive optics: FRIEND at CHARA
<BR /> Aims: In the context of the future developments of long baseline interferometry at visible wavelengths, we have built a prototype instrument called Fibered spectrally Resolved Interferometer – New Design (FRIEND) based on single mode fibers and a new generation detector called Electron Multiplying Charge-Coupled Device (EMCCD). Installed on the Center for High Angular […]
Physical properties of β Lyrae A and its opaque accretion disk
Mass exchange and mass loss in close binaries can significantly affect their evolution, but a complete self-consistent theory of these processes is still to be developed. Processes such as radiative shielding due to a hot-spot region, or a hydrodynamical interaction of different parts of the gas stream have been studied previously. In order to test […]