S18B0143abst
S18B0143
This is a follow-up observation of a sudden spectral change occurred around an OH/IR star IRAS19192+0922. Since OH/IR stars efficiently produce dust in their mass-loss winds, the investigation of their dust production activity is important to understand how they supply dust into space in their lives. The target has been thought to be continuously producing dust. However, we found a significant spectral change between 1983 and 1996 which suggests that it ceased the dust production to make a cavity in the dust shell. Obviously such a rapid change in the dust shell structure has never been noticed, and its spectroscopic monitoring in real time is vital to understand the mass-loss and the dust formation. We propose a COMICS spectroscopic observation of IRAS19192+0922 to investigate whether its dust production still has been dormant or not. We derive the current inner radius of the dust shell by model fitting of the spectrum. If an inner radius smaller than in 1996 is derived, it means the existence of hot dust formed after 1996, and intermittent behavior of the dust production will be unveiled. If a larger inner radius is derived, it means that the dust production is still dormant, and unknown environmental changes inhibiting dust formation around the star will be suggested.
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