We present two-dimensional ( 2D ) radiative transfer modeling of IRC $ $ +10 216 at selected moments of its evolution in 1995–2001 , which correspond to three epochs of our series of 8 near-infrared speckle images ( ) .
The high-resolution images obtained over the last 5.4 years revealed the dynamic evolution of the subarcsecond dusty environment of IRC $ $ +10 216 and our recent time-independent 2D radiative transfer modeling reconstructed its physical properties at the single epoch of January 1997 ( ) .
Having documented the complex changes in the innermost bipolar shell of the carbon star , we incorporate the evolutionary constraints into our new modeling to understand the physical reasons for the observed changes .
The new calculations show that our previous static model is consistent with the brightness variations seen in the near-infrared images , implying that during the last 50 years , we have been witnessing an episode of a steadily increasing mass loss from the central star , from \dot { M } \approx 10 ^ { -5 } M _ { \sun } yr ^ { -1 } to the rate of \dot { M } \approx 3 \times 10 ^ { -4 } M _ { \sun } yr ^ { -1 } in 2001 .
The rapid increase of the mass loss of IRC $ $ +10 216 and continuing time-dependent dust formation and destruction caused the observed displacement of the initially faint components C and D and of the bright cavity A from the star which has almost disappeared in our images in 2001 .
Increasing dust optical depths are causing strong backwarming that leads to higher temperatures in the dust formation zone , displacing the latter outward with a velocity v _ { T } \approx 27 km s ^ { -1 } due to the evaporation of the recently formed dust grains .
This self-regulating shift of the dust density peak in the bipolar shell mimics a rapid radial expansion , whereas the actual outflow has probably a lower speed v < v _ { \infty } \approx 15 km s ^ { -1 } .
The model predicts that the star will remain obscured until \dot { M } starts to drop back to lower values in the dust formation zone ; in a few years from that moment , we could be witnessing the star reappearing .