HD 166191 is a young late-F or early G-type star in the constellation Sagittarius.

The large amount of dust was interpreted as being produced by a recent collision of planetary embryos or by massive ongoing collisional grinding.

[5] Follow-up observations of the 2018-2019 brightening event[7] were carried out with Spitzer, ASAS-SN and the Hereford Arizona Observatory.

After two orbital periods the clump grew larger, but also optical thinner and no further dips could be observed.

[5] The event set off a chain reaction of impacts between the fragments of the first collision and other small bodies in the system.