The yellow hypergiant HR 5171 A: Resolving a massive interacting binary in the common envelope phase
Context. Only a few stars are caught in the very brief and often crucial stages when they quickly traverse the Hertzsprung-Russell diagram, and none has yet been spatially resolved in the mass transfer phase. <BR /> Aims: We initiated long-term optical interferometry monitoring of the diameters of massive and unstable yellow hypergiants (YHG) with the […]
Optical Interferometry and Adaptive Optics of Bright Transients
We present here our work on bright transients observed at an unprecedented spatial resolution with adaptive optics (8m-class telescopes) and long-baseline optical/infrared interferometry. These techniques allowed us to resolve the ejectas of classical and recurrent novae just a few days after discovery. We also present observations of the circumstellar environment wround the famous Intermediate Luminosity […]
Spectrally resolved interferometric observations of α Cephei and physical modeling of fast rotating stars
Context. When a given observational quantity depends on several stellar physical parameters, it is generally very difficult to obtain observational constraints for each of them individually. Therefore, we studied under which conditions constraints for some individual parameters can be achieved for fast rotators, knowing that their geometry is modified by the rapid rotation which causes […]
Evidence of an asymmetrical Keplerian disk in the Brγ and He I emission lines around the Be star HD 110432
Context. HD 110432 was classified as a γ Cas X-ray analog” since it has similar peculiar X-ray and optical characteristics
The binary Be star δ Scorpii at high spectral and spatial resolution. II. The circumstellar disk evolution after the periastron
Context. Classical Be stars are hot non-supergiant stars surrounded by a gaseous circumstellar disk that is responsible for the observed infrared (IR) excess and emission lines. The influence of binarity on these phenomena remains controversial. <BR /> Aims: We followed the evolution of the environment surrounding the binary Be star δ Scorpii one year before […]
Interactions in Massive Binary Stars as Seen by Interferometry
With the advent of large-collecting-area instruments, the number of objects that can be reached by optical long-baseline interferometry is steadily increasing. We present here a few results on massive binary stars, showing the interest of using this technique for studying the insight of interactions in these systems. Indeed, many massive stars with extended environments host, […]
Stars with the B[e] phenomenon seen by long baseline interferometry
Thanks to the high spatial resolution provided by long baseline interferometry, it is possible to understand the complex circumstellar geometry around stars with the B[e] phenomenon. These stars are composed by objects in different evolutionary stages, like high- and low-mass evolved stars, intermediate-mass pre-main sequence stars and symbiotic objects. However, up to now more than […]
VLTI, CHARA and NPOI Observations of Be Stars
In this review we will present recent results between 2005 and 2012 on the interferometric observations of circumstellar disks around active hot stars using the VLTI, CHARA and NPOI interferometers.
The relationship between γ Cassiopeiae’s X-ray emission and its circumstellar environment. II. Geometry and kinematics of the disk from MIRC and VEGA instruments on the CHARA Array
Context.γ Cas is thought to be the prototype of classical Be stars and is the most studied object among this group. However, as for all Be stars, the origin and the physics of its circumstellar disk responsible for the observed near IR-excess, emission lines, and peculiar X-ray emission is still being debated. <BR /> Aims: […]
Chromatic phase diversity for cophasing large array of telescopes
This paper reviews the recent laboratory results we have obtained on the demonstration of a cophasing algorithm based on the chromatic phase diversity method. The SIRIUS testbed was initially dedicated to the demonstration of the direct imaging capabilities of arrays of telescope. We have developed and numerically modeled a piston sensor based on the chromatic […]