# # Program information file # PROGRAM_ID 2021A018 PROGRAM_TITLE Characterizing the Variable Debris Disk Around HD 166191 PROGRAM_INV1 Kate Su PROGRAM_INV2 George Rieke PROGRAM_INV3 Taran Esplin PROGRAM_INV4 Michael Sitko PROGRAM_INV5 PROGRAM_SCICAT extra-solar planets PROGRAM_ABSTRACT_BEG Variable debris disks, discovered with Spitzer, give new insights to the collisional merging of planetary embryos and oligarchs over a period of about 200 Myr after protoplanetary disks have cleared. They have let us set timescales for the clearing of collisional debris, critical to understand the duty cycle of infrared excesses and the incidence of major planetesimal collisions. We can also monitor the orbital evolution of the initially optically thick clouds released in collisions. Our Spitzer monitoring ends in January, 2020 with the retiring of that mission. However, one system, HD 166191, has recently undergone a major series of collisions and is bright enough to monitor from the ground. Our pilot monitoring study in 2020 demonstrates that SpeX observations can track the evolution of the dust temperatures and levels of infrared excess, similar to the role of warm Spitzer. We propose to monitor the system in monthly timescales in 20A to track its long-term evolution. PROGRAM_ABSTRACT_END