IRTF Data Archive Program Information

# # Program information file # PROGRAM_ID 2021A050 PROGRAM_TITLE The ice complexity toward Ophiuchus molecular cloud PROGRAM_INV1 Will Rocha PROGRAM_INV2 Jes Jorgensen PROGRAM_INV3 Lars Kristensen PROGRAM_INV4 Giulia Perotti PROGRAM_INV5 Adwin Boogert PROGRAM_SCICAT stellar PROGRAM_ABSTRACT_BEG Ice mantles covering dust grains in space are thought to be composed by simple molecules such as CO to complex organic molecules [COMs] with more than six atoms [e.g., alcohols, aldehydes, ketones]. Laboratory experiments with ices involving either non-energetic or energetic mechanisms have shown that ices can contain those large molecules. From an observational perspective, several COMs have been identified in the gas-phase, and are likely results of thermal and non-thermal mechanisms to desorb frozen molecules to the gas-phase. Nevertheless, infrared observations suggest that CH3OH [methanol] is the simplest alcohol securely identified in the solid-phase toward star-forming regions. From that paradox, it is crucial to understand how chemically complex are the astrophysical ices and how abundant they are. To shed light on this problem, we propose to simultaneously observe K-, L- and M-bands [2.0 - 5.5 um] with SpeX/IRTF toward three protostars, WL17, ISO-Oph 21 and [GY92] 91 located in the Ophiuchus cloud. The K-band will be essential to estimate the continuum of ice features at both L- and M-bands. The L-band will detect O-H, C-H and N-H vibrational modes of simple and complex molecules, whereas the M-band will observe the CO ice molecule. These observations will be complemented by the Spitzer/IRS spectrum of the target sources and interpreted in light of the suggested detections of COMs by Rocha et al. [subm.]. Because a high signal-to-noise ratio [SNR] is required for ice observations, we propose an integration time per target of 1 hour [excluding overheads], with 1 second of single frame integration time to avoid saturation. This configuration will allow us to observe reach SNR = 50 at L-band and resolving power R = 900 and 1500 for a slit width of 0.5 and 0.8 arcsec, respectively. Auto-guiding with the target in the slit with the K-band filter will be used. PROGRAM_ABSTRACT_END