Expanding the C 3 H 6 O 2 isomeric interstellar inventory: Discovery of lactaldehyde and methoxyacetaldehyde in G+0.693-0.027
Year: 2026
Type: article
Abstract: Aims . The tentative detection of 3-hydroxypropanal (HO(CH 2 ) 2 C(O)H) toward the Galactic center molecular cloud G+0.693-0.027 prompts a systematic survey in this source aimed at detecting all C 3 H 6 O 2 isomers with available spectroscopy. Methods . We used an ultra-deep broadband spectral survey of G+0.693-0.027, carried out with the Yebes 40 m and IRAM 30 m telescopes, to conduct the astronomical search. Results . We report the first interstellar detection of lactaldehyde (CH 3 CH(OH)C(O)H) and methoxyacetaldehyde (CH 3 OCH 2 C(O)H), together with the second detections (i.e., confirmation) of methyl acetate (CH 3 C(O)OCH 3 ) and hydroxyacetone (CH 3 C(O)CH 2 OH), and new detections in this source of both anti - and g auche - conformers of ethyl formate (CH 3 CH 2 OC(O)H; the latter being tentative). For these species, we derived a fractional abundance relative to H 2 of ~(0.81, 0.24, 16, 1.6, 1.3, 1.4) × 10 −10 , respectively. In contrast, neither propionic acid, CH 3 CH 2 C(O)OH, nor glycidol, c-CH 2 OCHCH 2 OH (i.e., the most and the least stable species within the C 3 H 6 O 2 family, respectively) were detected, and we provide upper limits on their fractional abundances of ≤1.5 × 10 −10 and ≤3.7 × 10 −11 . Interestingly, all C 3 H 6 O 2 isomers can be synthesized through radical-radical reactions on the surface of dust grains, ultimately tracing back to CO as the parent molecule. We suggest that formation of the detected isomers is mainly driven by successive hydrogenation of CO, producing CH 3 OH and CH 3 CH 2 OH as the primary parent species. Conversely, propionic acid is thought to originate from the oxygenation of CO via the HOCO intermediate, which help us rationalize its non-detection. Overall, our findings notably expand the known chemical inventory of the interstellar medium and provide direct observational evidence that increasingly complex chemistry involving O-bearing species occurs in space.
Source: Astronomy and Astrophysics
Authors: M. Sanz-Novo, V. M. Rivilla, I. Jiménez-Serra, L. Colzi, S. Zeng, A. Megías, D. San Andrés, Á. López-Gallifa, A. Martínez-Henares, Z. T. P. Fried, B. A. McGuire, S. Martín, M. A. Requena-Torres, B. Tercero, P. de Vicente, L. Kolesniková, E. R. Alonso, E. J. Cocinero, J. C. Guillemin, I. Kleiner
Institutions: Centro de Astrobiología, Universidad Complutense de Madrid, Massachusetts Institute of Technology, National Radio Astronomy Observatory, European Southern Observatory, Atacama Large Millimeter Submillimeter Array, European Southern Observatory, Towson University, Yebes Observatory, Spanish National Observatory, University of Chemistry and Technology, Prague, Universidad de Valladolid, Consejo Superior de Investigaciones Científicas, University of the Basque Country, Instituto Biofisika, Centre National de la Recherche Scientifique, Institut des Sciences Chimiques de Rennes, École Nationale Supérieure de Chimie de Rennes, Université de Rennes, Université Paris-Est Créteil, Université Paris Cité, Laboratoire Interuniversitaire des Systèmes Atmosphériques
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
Funders: Comunidad de Madrid, Ministerio de Ciencia, Innovación y Universidades, European Commission, Agence Nationale de la Recherche, Grantová Agentura České Republiky, Centre National d’Etudes Spatiales, Eusko Jaurlaritza, Max-Planck-Gesellschaft, Centre National de la Recherche Scientifique, Ministerio de Ciencia e Innovación, Consejo Superior de Investigaciones Científicas, European Regional Development Fund, Agencia Estatal de Investigación, European Social Fund
Awards: G10949448, G1105844351, G1175115578, G1272900390, G1274526653, G1401168639, G1416831901, G1507096846, G1515373893, G1743472294, G1853093169, G1855990336, G1910261178, G195474297, G205929289, G2116508696, G2262748287, G2296187950, G2309174360, G2350454921, G24120701, G252646220, G2601397997, G2660406951, G294895050, G300979063, TOWARDS THE DETECTION OF EXOPLANET BIOSIGNATURES WITH LARGE AMPLITUDE MOTIONS USING HIGH RESOLUTION SPECTROSCOPY, G3428307696, G3443738222, G3470217882, G3480869486, G3518538256, G3681454997, G3702198118, G3926228249, G3926388292, G4033406476, G4042783231, G4049322340, G4085408077, G410571670, G4212894969, G4240073238, G425668148, G430777504, G4384110019, G4390319345, G451917667, G464105488, G491712853, G5080475149, G508095407, G5195188938, G523076202, G5421974903, G5539308778, G5542129504, G5572486069, G5635532810, G5721199125, G582065459, G593054264, G5943232429, G5967599077, G6033112984, G6080697404, G6218905885, G6326031618, G6353647700, G6719929187, G6874468849, G7084143925, G7097722406, G7127239378, G7184498898, G7387325513, G7395345766, Precursors of prebiotic molecules: structure, formation and searches in space, G7430849242, G745419941, G757437891, G7780475403, G7805626310, G7863371703, G8413134427, G8497050386, G8510625649, G855041801, G8575141037, G8667377315, G8709270594, G8829154781, G8888022036, G8920660035, G8985351591, G901676405, G99296377
OpenAlex ID: W7124159795