RT info:eu-repo/semantics/article
T1 Toward the limits of complexity of interstellar chemistry: Rotational spectroscopy and astronomical search for n- and i-butanal
A1 Sanz-Novo, M.
A1 Belloche, A.
A1 Rivilla, V. M.
A1 Garrod, R. T.
A1 Kolesniková, L.
A1 Valle, J. C.
A1 Rodríguez-Almeida, L.
A1 Jimenez-Serra, I.
A1 Martín-Pintado, J.
A1 Müller, H. S. P.
A1 Menten, K. M.
A1 Sanz Novo, Miguel
A1 Alonso Hernández, José Luis
A1 Redondo Cristóbal, María del Pilar
A1 Barrientos Benito, María Carmen
A1 menten
K1 ISM: molecules
K1 molecular data
K1 astrochemistry
K1 line: identification
K1 ISM: individual objects: Sagittarius B2
K1 ISM: individual objects: G+0.693-0.027
AB Context. In recent times, large organic molecules of exceptional complexity have been found in diverse regions of the interstellarmedium.Aims. In this context, we aim to provide accurate frequencies of the ground vibrational state of two key aliphatic aldehydes, n-butanaland its branched-chain isomer, i-butanal, to enable their eventual detection in the interstellar medium. We also want to test the level ofcomplexity that interstellar chemistry can reach in regions of star formation.Methods. We employ a frequency modulation millimeter-wave absorption spectrometer to measure the rotational features of n- andi-butanal. We analyze the assigned rotational transitions of each rotamer separately using the A-reduced semirigid-rotor Hamiltonian.We use the spectral line survey ReMoCA performed with the Atacama Large Millimeter/submillimeter Array to search for n- and ibutanaltoward the star-forming region Sgr B2(N). We also search for both aldehydes toward the molecular cloud G+0.693-0.027 withIRAM 30m and Yebes 40m observations. The observational results are compared with computational results from a recent gas-grainastrochemical model.Results. Several thousand rotational transitions belonging to the lowest-energy conformers of two distinct linear and branched isomershave been assigned in the laboratory spectra up to 325 GHz. A precise set of the relevant rotational spectroscopic constants has beendetermined for each structure as a first step toward identifying both molecules in the interstellar medium.We report non-detections of nandi-butanal toward both sources, Sgr B2(N1S) and G+0.693-0.027. We find that n- and i-butanal are at least 2–6 and 6–18 times lessabundant than acetaldehyde toward Sgr B2(N1S), respectively, and that n-butanal is at least 63 times less abundant than acetaldehydetoward G+0.693-0.027. While propanal is not detected toward Sgr B2(N1S) either, with an abundance at least 5–11 lower than thatof acetaldehyde, propanal is found to be 7 times less abundant than acetaldehyde in G+0.693-0.027. Comparison with astrochemicalmodels indicates good agreement between observed and simulated abundances (where available). Grain-surface chemistry appearssufficient to reproduce aldehyde ratios in G+0.693-0.027; gas-phase production may play a more active role in Sgr B2(N1S). Modelestimates for the larger aldehydes indicate that the observed upper limits may be close to the underlying values.Conclusions. Our astronomical results indicate that the family of interstellar aldehydes in the Galactic center region is characterizedby a drop of one order of magnitude in abundance at each incrementation in the level of molecular complexity
PB EDP Sciences
SN 0004-6361
YR 2022
FD 2022
LK https://uvadoc.uva.es/handle/10324/65169
UL https://uvadoc.uva.es/handle/10324/65169
LA spa
NO A&A 666, A114 (2022)
NO Producción Científica
DS UVaDOC
RD 07-ene-2025