Proposal #272

This is a follow-on proposal to Proposal 252 that was successfully executed during the first half of 2022. The original proposal was an approved coordinated monitoring program involving same-night AAVSO BVRI imaging photometry using the BSM telescopes, near-infrared spectroscopy with the NASA IRTF+SpeX, and the LCOGT network of 1m telescopes+NRES for high-res optical spectroscopy. The AAVSO and IRTF observations were successful, but due to ongoing telescope and instrument failures the LCO optical spectroscopy was mostly unsuccessful, hampering the full intent of the science program, which is to time-resolve the decretion disk formation and dissipation events that occur during modest outbursts of Be stars. The data already obtained are being analyzed by my undergraduate students and myself and will produce valuable insight into the physics of Be stars, though there is a paucity of optical spectroscopy. To pursue the full objectives of the original science program proposed, we have needed to change facilities for the optical high-resolution spectroscopy, moving to the southern hemisphere that required selection of a new set of stars. We have an approved allocation of 2022B time for the NOIRLab SMARTS 1.5m using Chiron to monitor 8-new Be stars shown to undergo frequent outbursts that are accessible by the suite of multi-facilities (SMARTS+IRTF+AAVSO); our previous targets were not accessible from CTIO. SMARTS can accommodate our need to schedule same night spectroscopy in the optical with those being obtained on scheduled nights with the IRTF and should prove more reliable in obtaining the data we need for the program. We request AAVSO-BSM nightly BVRI monitoring as executed in last semester's program for the new set of 8 Be stars through at least February 2023. If R,I filters are unavailable on any particular telescope, r,i can be used instead. Given that the new set of stars are on average brighter in the optical, combined with the 50% larger aperture of the SMARTS telescope, the optical spectroscopy will be secured more quickly and efficiently, minimizing self-competition and allowing completion of the nightly observations. Another modification to the program logistics is we have requested scheduling of the IRTF nights to be shorter per night (2 hrs/night) but spread over 2 adjacent nights per monitoring interval, allowing easier scheduling for the optical spectroscopy which requires longer exposure times per target. The original science justification given in Proposal 252 remains valid and we refer to that previous presentation. I can reattach that justification here if needed - just let me know. The typical brightness of the new targets range from V=9.9-8.6, so exposure times with the BSM telescopes remain short. This project comprises the two advanced undergraduate students senior research projects in preparation for graduate studies and so will continue working on this program with me.