Bispectrum speckle interferometry and future long-baseline interferometry of the carbon star IRC+10216

We present near-infrared (JHK) bispectrum speckle-interferometry monitoring of IRC + 10 216 obtained with the SAO 6 m telescope. The present speckle observations covering baselines up to 6 m provide important complementary informations for future long-baseline interferometry. To disentangle the apparent motions of the various IRC + 10 216 components and to reveal the location of the central star, future high-resolution observations are of utmost value for the interpretation of this astrophysical key object. The J-, H-, and K-band resolutions of our speckle observations are 50 mas, 56 mas, and 73 mas, resp. The K-band observations cover 8 different epochs from 1995 to 2001 and show the dynamical evolution of the dust shell which consists of several compact components within a 200 milli-arcsecond radius. Our recent two-dimensional radiative transfer modelling has shown that the central star is probably not located at the brightest dust-shell component A but at the position of the northern component B. The bright and compact component A is the southern lobe of a bipolar structure. The changes of the dust-shell structure can be related to corresponding changes of the optical depth caused, for instance, by mass-loss variations. The present observations are consistent with the predictions of hydrodynamical models that enhanced dust formation takes place on a timescale of several pulsational cycles.