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# Program information file
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PROGRAM_ID           2023A065
PROGRAM_TITLE        First Measurements of Parent Volatiles Composition of Anomalous Comet 96P/Machholz 1.
PROGRAM_INV1         Mohammad Saki
PROGRAM_INV2         Erika Gibb
PROGRAM_INV3         Boncho Bonev
PROGRAM_INV4         Michael DiSanti
PROGRAM_INV5         Neil Dello Russo
PROGRAM_SCICAT       comets
PROGRAM_ABSTRACT_BEG
We propose to use iSHELL to measure parent composition of coma gases [H2O, HCN, C2H2, NH3, CH4, C2H6, CH3OH, H2CO, CO, and OCS] released from ices in the nucleus of Jupiter-family comet [JFC] 96P/Machholz 1. We emphasize three equally important goals: [1] JFCs as an under-represented group in taxonomic studies of parent volatiles, [2] determine abundances of hypervolatiles CO and CH4, and [3] Determining the primary-fragment relationship. 96P's anomalous composition in fragment species and unusual orbit suggested that it could have formed in compositionally different parts of the protoplanetary disk or have interstellar origins. It does not fit in any taxonomic class based on fragment species, so studies of parent volatiles can potentially have a high impact. 96P's high Doppler shift is sufficient for shifting cometary emissions [particularly for CO and CH4] out of their telluric counterparts, allowing us to detect or put stringent upper limits on both species. We will use three iSHELL settings: Lcustom [~2.8-3.1 um, sampling H2O, HCN, NH3, and C2H2]; Lp1 [~3.2-3.6 um, sampling CH4, C2H6, CH3OH, H2CO, and OH*, a proxy for the production and spatial distribution of its parent, H2O]; and M2 [~4.5-5.2 um, sampling H2O, CO, and OCS]. We will use the 3.46 um filter to guide on 96P with Kyle during the day, as this filter covers generally strong gas emission. Due to the day-time nature of 96P and low sensitivity of previous near-IR spectrographs, the parent volatile composition of comet 96P has never been studied before. The 2023A semester provides a rare [and excellent] opportunity to measure its parent volatile abundances for the first time. Owing to its high resolving power, spectral coverage, flexible daytime scheduling for serial observation, and superior M-band guiding, these studies can only be done with iSHELL at NASA-IRTF.
PROGRAM_ABSTRACT_END