Stanislav Štefl

THE FIRST DETERMINATION OF THE VISCOSITY PARAMETER IN THE CIRCUMSTELLAR DISK OF A Be STAR

Be stars possess gaseous circumstellar decretion disks, which are well described using standard

Imaging the heart of astrophysical objects with optical long-baseline interferometry

\alpha

The Very Large Telescope Interferometer: an update

-disk theory. The Be star 28 CMa recently underwent a long outburst followed by a long period of quiescence, during which the disk dissipated. Here we present the first time-dependent models of the dissipation of a viscous decretion disk. By modeling the rate of decline of the V-band excess, we determine that the viscosity parameter

Recent progress at the Very Large Telescope Interferometer

\alpha=1.0\pm0.2

Revealing the structure of the outer disks of Be stars

, corresponding to a mass injection rate

The Outer Disk of the Classical Be Star ψ Per

\dot{M}=(3.5\pm 1.3) \times 10^{-8}\ M_\sun\,\mathrm{yr}^{-1}

Long-term trends in the VLTI auxiliary telescopes and ESO/APEX pointing models

. Such a large value of

Active B‐Stars

\alpha

The spin-orbit alignment of the Fomalhaut planetary system probed by optical long baseline interferometry

suggests that the origin of the turbulent viscosity is an instability in the disk whose growth is limited by shock dissipation. The mass injection rate is more than an order of magnitude larger than the wind mass loss rate inferred from UV observations, implying that the mass injection mechanism most likely is not the stellar wind, but some other mechanism.

Simultaneous photometry and spectroscopy of the Be star 28 (ω) CMa — II. Line profile modelling

The number of publications of aperture-synthesis images based on optical long-baseline interferometry measurements has recently increased due to easier access to visible and infrared interferometers. The interferometry technique has now reached a technical maturity level that opens new avenues for numerous astrophysical topics requiring milli-arcsecond model-independent imaging. In writing this paper our motivation was twofold: (1) review and publicize emblematic excerpts of the impressive corpus accumulated in the field of optical interferometry image reconstruction; (2) discuss future prospects for this technique by selecting four representative astrophysical science cases in order to review the potential benefits of using optical long-baseline interferometers.For this second goal we have simulated interferometric data from those selected astrophysical environments and used state-of-the-art codes to provide the reconstructed images that are reachable with current or soon-to-be facilities. The image-reconstruction process was “blind” in the sense that reconstructors had no knowledge of the input brightness distributions. We discuss the impact of optical interferometry in those four astrophysical fields. We show that image-reconstruction software successfully provides accurate morphological information on a variety of astrophysical topics and review the current strengths and weaknesses of such reconstructions.We investigate how to improve image reconstruction and the quality of the image possibly by upgrading the current facilities. We finally argue that optical interferometers and their corresponding instrumentation, existing or to come, with six to ten telescopes, should be well suited to provide images of complex sceneries.