Abstract:
Optical stellar interferometers have demonstrated milli-arcsecond
resolution with few apertures spaced tens of meters apart. Results from the area
of stellar angular diameters with implications for emergent fluxes, effective
temperatures, luminosities and structure of the stellar atmosphere, dust and gas
envelopes, binary star orbits with impact on cluster distances and stellar
masses, relative sizes of emission-line stars and emission region, stellar
rotation, limb-darkening, and astrometry have been published. However, in
order to obtain snapshot images, many-apertures would be required, for a better
sampling of the incoming wavefront. The coherent imaging thus achievable
improves the sensitivity with respect to the incoherent combination of
successive fringed exposures, heretofore achieved in the form of optical
aperture synthesis. For efficient use of a multi-aperture imaging interferometer,
this can be done with pupil densification, a technique also called hypertelescope
imaging. When equipped with a coronagraph, this can be used for imaging of
exo-planet transits across a resolved star. The capabilities of such a technique
can be envisaged through a simulated image carried out recently by Surya et al.
[1]. This lecture is aimed to describe some of these techniques and methods.