S19B0137

This is a follow-up observation of a sudden spectral change found in an OH/IR star IRAS19192+0922. Since OH/IR stars are AGB stars actively producing dust, investigations of their dust production activity are important to understand the dust yield of AGB stars. 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 their dust production activityies. We propose a COMICS spectroscopic observation of IRAS19192+0922 to investigate whether its dust production is still 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. This result suggests a possibility that the dust production activity is inhibited by evolutoinary changes of stellar properties related to a thermal pulse event.


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