On The Origin Of Infrared Bands Attributed To Tryptophan In Spitzer Observations Of IC 348

By Keith Cowing
Status Report
May 28, 2024
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On The Origin Of Infrared Bands Attributed To Tryptophan In Spitzer Observations Of IC 348
The amino acid Tryptophan — Wikipedia

Infrared emission features toward interstellar gas of the IC 348 star cluster in Perseus have been recently proposed to originate from the amino acid tryptophan.

The assignment was based on laboratory infrared spectra of tryptophan pressed into pellets, a method which is known to cause large frequency shifts compared to the gas phase. We assess the validity of the assignment based on the original Spitzer data as well as new data from JWST.

In addition, we report new spectra of tryptophan condensed in para-hydrogen matrices to compare with the observed spectra. The JWST MIRI data do not show evidence for tryptophan, despite deeper integration toward IC 348. In addition, we show that several of the lines attributed to tryptophan are likely due to instrumental artifacts.

This, combined with the new laboratory data, allows us to conclude that there is no compelling evidence for the tryptophan assignment.

Comparison of the Spitzer-IRS archival spectrum of IC 348 (orange) with our laboratory spectrum of Trp isolated in p-H2 (blue) and Trp in KBr pellets (red) from the NIST Chemistry Webbook. The wavelengths of the features attributed to Trp by IG23 are shown in the grey dashed lines. The Spitzer spectrum (orange) is of the dedicated background observation (AOR 22848512). Zoomed panels are centred around the features attributed to Trp by IG23. –astro-ph.GA

Aditya Dhariwal, Thomas H. Speak, Linshan Zeng, Amirhossein Rashidi, Brendan Moore, Olivier Berné, Anthony J. Remijan, Ilane Schroetter, Brett A. McGuire, Víctor M. Rivilla, Arnaud Belloche, Jes K. Jørgensen, Pavle Djuricanin, Takamasa Momose, Ilsa R. Cooke

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2405.16773 [astro-ph.GA] (or arXiv:2405.16773v1 [astro-ph.GA] for this version)
Submission history
From: Ilsa Cooke
[v1] Mon, 27 May 2024 02:54:35 UTC (1,167 KB)
Astrobiology, Astrochemistry,

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