Three recipes for improving the image quality with optical long-baseline interferometers: BFMC, LFF, and DPSC
We present here three recipes for getting better images with optical interferometers. Two of them, Low- Frequencies Filling and Brute-Force Monte Carlo were used in our participation to the Interferometry Beauty Contest this year and can be applied to classical imaging using V<SUP>2</SUP> and closure phases. These two addition to image reconstruction provide a way […]
First spectro-interferometric survey of Be stars. I. Observations and constraints on the disk geometry and kinematics
Context. Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared-excess and emission lines. The phenomena involved in the disk formation still remain highly debated. <BR /> Aims: To progress in the understanding of the physical process or processes responsible for the mass ejections and […]
Spatially resolving the outer atmosphere of the M giant BK Virginis in the CO first overtone lines with VLTI/AMBER
Context. The mass-loss mechanism in normal K-M giant stars with small variability amplitudes is not yet understood, although the majority among red giant stars are precisely of this type. <BR /> Aims: We present high-spatial and high-spectral resolution observations of the M7 giant BK Vir with AMBER at the Very Large Telescope Interferometer (VLTI). Our […]
The 2011 outburst of the recurrent nova <ASTROBJ>T Pyxidis</ASTROBJ>. Evidence for a face-on bipolar ejection
<BR /> Aims: T Pyx is the first recurrent nova ever historically studied. It was seen in outburst six times between 1890 and 1966 and then not for 45 years. We report on near-IR interferometric observations of the recent outburst of 2011. <BR /> Methods: We obtained near-IR observations of <ASTROBJ>T Pyx</ASTROBJ> at dates ranging […]
The binary Be star δ Scorpii at high spectral and spatial resolution. I. Disk geometry and kinematics before the 2011 periastron
Context. Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed IR-excess and emission lines. The influence of binarity on these phenomena remains controversial. Aims.δ Sco is a binary system whose primary suddenly began to exhibit the Be phenomenon at the last periastron in 2000. We […]
Images of unclassified and supergiant B[e] stars disks with interferometry
B[e] stars are among the most peculiar objects in the sky. This spectral type, characterised by allowed and forbidden emission lines, and a large infrared excess, does not represent an homogenous class of objects, but instead, a mix of stellar bodies seen in all evolutionary status. Among them, one can find Herbig stars, planetary nebulae […]
Imaging “Pinwheel” nebulae with optical long-baseline interferometry
Dusty Wolf-Rayet stars are few but remarkable in terms of dust production rates (up to Ṁ = 10<SUP>-6</SUP> M<SUB>solar</SUB>/yr). Infrared excesses associated to mass-loss are found in the sub-types WC8 and WC9. Few WC9d stars are hosting a “pinwheel” nebula, indirect evidence of a companion star around the primary. While few other WC9d stars have […]
Resolving the dusty circumstellar environment of the A[e] supergiant HD 62623 with the VLTI/MIDI
HD 62623 is one of the very few A-type supergiants showing the B[e] phenomenon. We studied the geometry of its circumstellar envelope in the mid-infrared using the VLTI/MIDI instrument. Using the radiative transfer code MC3D, we managed to model it as a dusty disk with an inner radius of 3.85 AU, an inclination angle of […]
Kinematics and geometrical study of the Be stars 48 Persei and ψ Persei with the VEGA/CHARA interferometer
Context. Five different physical processes might be responsible for the formation of decretion disks around Be stars: fast rotation of the star, stellar pulsations, binarity, stellar winds, and magnetic fields. Our observations indicate that fast rotation seems to produce a disk in Keplerian rotation, at least in the specific case of the two stars observed. […]
The Galactic unclassified B[e] star HD 50138. II. Interferometric constraints on the close circumstellar environment
Context. HD 50138 is a southern star that presents the B[e] phenomenon, but its evolutionary stage is still not well known. This object presents spectral variability, which can be explained by outbursts or shell phases. Spectropolarimetric observations have shown the presence of a non-spherically symmetric circumstellar environment that is responsible for the B[e] phenomenon. However, […]