# # Program information file # PROGRAM_ID 2023B080 PROGRAM_TITLE High Resolution Infrared Spectra of Stellar Mergers PROGRAM_INV1 Michael Connelley PROGRAM_INV2 Kishalay De PROGRAM_INV3 PROGRAM_INV4 PROGRAM_INV5 PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Since many stars are born with a close companion, binary interactions play a key role that can lead to mass transfer creating a common envelope system. The observational manifestations of common envelope formation are now established to be associated with a class of spectacular stellar eruptions called the 'red novae'. Red novae are accompanied by relatively short-lived optical outbursts together with extremely long-lived infrared emission arising from dusty envelopes that enshroud the inner remnant for years to decades. Identifying red nova outbursts in the Galactic plane amongst eruptions such as young stars remains a daunting task, especially with i] unknown distances [i.e. luminosity] of the eruptions. The NIR spectroscopic diagnostics for a particular type of young stellar eruptions called FUors are strikingly similar to those of red novae. Together with the lack of luminosity diagnostics, their strikingly similar appearances open the uncomfortable possibility that many Galactic red novae have been historically misclassified as protostellar outbursts! The CO bandhead at ~ 2.29 um is one of the strongest features protostellar outbursts, as well as in the cold outflows of stellar mergers. Existing high resolution spectra of FUors exhibit broad blended features with kinematic widths of ~> 50 km s. The goal of this project is to observe the CO absorption lines of a stellar merger at high resolution. Here, we request to obtain the first high resolution K band spectra of these events to compare their line profiles with existing FUor spectra to i] conclusively identify stellar mergers misclassified as FUors and ii] obtain the first independent diagnostics of the gas accretion geometry in Galactic stellar mergers via the CO bandhead line profiles. If the line profiles are found to be consistent, then that would suggest a common mechanism for stellar mergers and FUors. PROGRAM_ABSTRACT_END