Artistic rendition of tryptophan molecular structures in the star-creating zone of IC 348, situated in the Perseus constellation. Image courtesy: Gabriel Pérez Díaz (IAC)
Tryptophan ranks as one of the essential 20 amino acids imperative for the creation of proteins, a fundamental process for the evolution of life on Earth. Previous work by IAC researcher Susana Iglesias Groth has extensively characterized this amino acid’s various spectral attributes in the infrared spectrum.
Data acquired from the Spitzer Space Observatory enabled her to discern more than 10 emission bands pertaining to this molecule, with the most potent of these conforming to her lab-based observations.
“The ample spectral data available in the infrared range, coupled with the extensive spectroscopic database from the Spitzer Space Observatory, made this amino acid a prime target for extraterrestrial detection,” clarifies the astrophysicist.
The research incorporated information from multiple zones of star and planetary genesis. However, the maximum level of sensitivity was achieved in the Perseus molecular cloud complex, specifically in the star system IC 348. It was here that a synthesis of all the gathered spectroscopic data enabled the identification of emission lines, analogous to those produced by tryptophan in laboratory settings.
Iglesias-Groth notes, “Owing to its proximity to Earth, IC 348 serves as an unparalleled celestial incubator and a sophisticated chemical lab, enabling highly sensitive molecular explorations in interstellar space.” She has also recently found evidence of other molecules in this region, including water (H2O), carbon dioxide (CO2), hydrogen cyanide (HCN), acetylene (C2H), benzene (C6H6), polycyclic aromatic hydrocarbons, and fullerenes, to name a few.
Image credit: Jorge Rebolo-Iglesias, Background: NASA/Spitzer Space Telescope
“The groundbreaking aspect of this study is that tryptophan has been discovered in interstellar space for the first time. Moreover, despite years of rigorous investigation, no other amino acids have been definitively detected in any star-forming areas,” highlights the researcher.
The study introduces compelling evidence that emission lines related to tryptophan might be commonplace in other star-forming locales as well. “It is plausible that amino acids, which serve as the foundational elements of proteins, are enriching the gases within protoplanetary disks and the atmospheres of nascent exoplanets, potentially expediting the onset of life on these celestial bodies,” states Iglesias-Groth.
Furthermore, emission band analysis has provided an estimation of the ambient temperature in which this molecule exists within the gaseous cloud: approximately 280 Kelvin or near freezing point, closely mirroring temperatures previously recorded for molecular hydrogen and water in IC 348’s interstellar medium.
Iglesias-Groth elucidates, “Amino acids are known to be constituents of meteorites and might have been present during the early stages of our Solar System’s formation. The identification of tryptophan, and possibly other amino acids in the future, could signify that essential life-forming agents naturally occur in the very regions where stars and planetary systems come into existence. This could potentially imply that life is more ubiquitous in our galaxy than previously assumed.”
Reference: “A search for tryptophan in the gas of the IC 348 star cluster of the Perseus molecular cloud” by Susana Iglesias-Groth, published on 22 May 2023 in the Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stad1535
