Examinando por Autor "Colzi, L."

Mostrando 1 - 4 de 4

Acceso Abierto
Discovery in space of ethanolamine, the simplest phospholipid head group
(National Academy of Sciences, 2021-06-01) Rivilla, V. M.; Jiménez Serra, I.; Martín Pintado, J.; Briones, C.; Rodríguez Almeida, L. F.; Rico Villas, F.; Tercero, B.; Zeng, S.; Colzi, L.; De Vicente, P.; Martín, S.; Requena Torres, Miguel Angel; European Commission (EC); Agencia Estatal de Investigación (AEI); Comunidad de Madrid; Rivilla, V. M. [0000-0002-2887-5859]; Tercero, B. [0000-0002-4782-5259]; Martín, S. [0000-0001-9281-2919]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Cell membranes are a key element of life because they keep the genetic material and metabolic machinery together. All present cell membranes are made of phospholipids, yet the nature of the first membranes and the origin of phospholipids are still under debate. We report here the presence of ethanolamine in space, NH2CH2CH2OH, which forms the hydrophilic head of the simplest and second-most-abundant phospholipid in membranes. The molecular column density of ethanolamine in interstellar space is N = (1.51 +/- 0.07) x 1013 cm-2, implying a molecular abundance with respect to H2 of (0.9 - 1.4) x 10-10. Previous studies reported its presence in meteoritic material, but they suggested that it is synthesized in the meteorite itself by decomposition of amino acids. However, we find that the proportion of the molecule with respect to water in the interstellar medium is similar to the one found in the meteorite (10-6). These results indicate that ethanolamine forms efficiently in space and, if delivered onto early Earth, could have contributed to the assembling and early evolution of primitive membranes.
Acceso Abierto
First survey of HCNH+ in high-mass star-forming cloud cores
(EDP Sciences, 2021-07-23) Fontani, F.; Colzi, L.; Redaelli, E.; Sipilä, O.; Caselli, P.; Agencia Estatal de Investigación (AEI); European Commission (EC); Comunidad de Madrid
Context. Most stars in the Galaxy, including the Sun, were born in high-mass star-forming regions. It is hence important to study the chemical processes in these regions to better understand the chemical heritage of the Solar System and most of the stellar systems in the Galaxy. Aims. The molecular ion HCNH+ is thought to be a crucial species in ion-neutral astrochemical reactions, but so far it has been detected only in a handful of star-forming regions, and hence its chemistry is poorly known. Methods. We observed with the IRAM 30 m Telescope 26 high-mass star-forming cores in different evolutionary stages in the J = 3−2 rotational transition of HCNH+. Results. We report the detection of HCNH+ in 16 out of 26 targets. This represents the largest sample of sources detected in this molecular ion to date. The fractional abundances of HCNH+ with respect to H2, [HCNH+], are in the range 0.9−14 × 10−11, and the highest values are found towards cold starless cores, for which [HCNH+] is of the order of 10−10. The abundance ratios [HCNH+]/[HCN] and [HCNH+]/[HCO+] are both ≤0.01 for all objects except for four starless cores, which are well above this threshold. These sources have the lowest gas temperatures and average H2 volume density values in the sample. Based on this observational difference, we ran two chemical models, ‘cold’ and ‘warm’, which attempt to match the average physical properties of the cold(er) starless cores and the warm(er) targets as closely as possible. The reactions occurring in the latter case are investigated in this work for the first time. Our predictions indicate that in the warm model HCNH+ is mainly produced by reactions with HCN and HCO+, while in the cold model the main progenitor species of HCNH+ are HCN+ and HNC+. Conclusions. The observational results indicate, and the model predictions confirm, that the chemistry of HCNH+ is different in cold–early and warm–evolved cores, and the abundance ratios [HCNH+]/[HCN] and [HCNH+]/[HCO+] can be useful astrochemical tools to discriminate between different evolutionary phases in the process of star formation.
Acceso Abierto
The GUAPOS project: G31.41+0.31 Unbiased ALMA sPectral Observational Survey I. Isomers of C2H4O2
(EDP Sciences, 2020-12-02) Mininni, C.; Beltrán, M. T.; Rivilla, V. M.; Sánchez Monge, Álvaro; Fontani, F.; Möller, T.; Cesaroni, R.; Schilke, P.; Viti, S.; Jiménez Serra, I.; Colzi, L.; Lorenzani, A.; Testi, L.; Ministero dell'Istruzione, dell'Università e della Ricerca (MIUR); Agencia Estatal de Investigación (AEI); European Research Council (ERC); Mininni, C. [0000-0002-2974-4703]; Beltrán Sorolla, M. T. [0000-0003-3315-5626]; Rivilla, V. M. [0000-0002-2887-5859]; Sánchez Monge, A. [0000-0002-3078-9482]; Fontani, F. [0000-0003-0348-3418]; Möller, T. [0000-0002-9277-8025]; Cesaroni, R. [0000-0002-2430-5103]; Schilke, P. [0000-0003-2141-5689]; Viti, S. [0000-0001-8504-8844]; Jiménez Serra, I. [0000-0003-4493-8714]; Colzi, L. [0000-0001-8064-6394]; Lorenzani, A. [0000-0002-4685-3434]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
Context. One of the goals of astrochemistry is to understand the degree of chemical complexity that can be reached in star-forming regions, along with the identification of precursors of the building blocks of life in the interstellar medium. To answer such questions, unbiased spectral surveys with large bandwidth and high spectral resolution are needed, in particular, to resolve line blending in chemically rich sources and identify each molecule (especially for complex organic molecules). These kinds of observations have already been successfully carried out, primarily towards the Galactic Center, a region that shows peculiar environmental conditions. Aims. We present an unbiased spectral survey of one of the most chemically rich hot molecular cores located outside the Galactic Center, in the high-mass star-forming region G31.41+0.31. The aim of this 3mm spectral survey is to identify and characterize the physical parameters of the gas emission in different molecular species, focusing on complex organic molecules. In this first paper, we present the survey and discuss the detection and relative abundances of the three isomers of C2H4O2: methyl formate, glycolaldehyde, and acetic acid. Methods. Observations were carried out with the ALMA interferometer, covering all of band 3 from 84 to 116 GHz (~32 GHz bandwidth) with an angular resolution of 1.2′′ × 1.2′′ (~ 4400 au × 4400 au) and a spectral resolution of ~0.488 MHz (~1.3−1.7 km s−1). The transitions of the three molecules have been analyzed with the software XCLASS to determine the physical parameters of the emitted gas. Results. All three isomers were detected with abundances of (2 ± 0.6) × 10−7, (4.3−8) × 10−8, and (5.0 ± 1.4) × 10−9 for methyl formate, acetic acid, and glycolaldehyde, respectively. Methyl formate and acetic acid abundances are the highest detected up to now, if compared to sources in the literature. The size of the emission varies among the three isomers with acetic acid showing the most compact emission while methyl formate exhibits the most extended emission. Different chemical pathways, involving both grain-surface chemistry and cold or hot gas-phase reactions, have been proposed for the formation of these molecules, but the small number of detections, especially of acetic acid and glycolaldehyde, have made it very difficult to confirm or discard the predictions of the models. The comparison with chemical models in literature suggests the necessity of grain-surface routes for the formation of methyl formate in G31, while for glycolaldehyde both scenarios could be feasible. The proposed grain-surface reaction for acetic acid is not capable of reproducing the observed abundance in this work, while the gas-phase scenario should be further tested, given the large uncertainties involved.
Restringido
Thiols in the Interstellar Medium: First Detection of HC(O)SH and Confirmation of C2H5SH
(IOP Science Publishing, 2021-04-30) Rodríguez Almeida, L. F.; Jiménez Serra, I.; Rivilla, V. M.; Martín Pintado, J.; Zeng, S.; Tercero, B.; De Vicente, P.; Colzi, L.; Rico Villas, F.; Martín, S.; Requena Torres, Miguel Angel; Comunidad de Madrid; Agencia Estatal de Investigación (AEI); European Research Council (ERC); European Commission (EC); Rodríguez Almeida, L. F. [0000-0002-9785-703X]; Jiménez Serra, I. [0000-0003-4493-8714]; Rivilla, V. M. [0000-0002-2887-5859]; Martín Pintado, J. [0000-0003-4561-3508]; Tercero, B. [0000-0002-4782-5259]; Martín, S. [0000-0001-9281-2919]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The chemical compounds carrying the thiol group (-SH) have been considered essential in recent prebiotic studies regarding the polymerization of amino acids. We have searched for this kind of compound toward the Galactic Center quiescent cloud G+0.693–0.027. We report the first detection in the interstellar space of the trans-isomer of monothioformic acid (t-HC(O)SH) with an abundance of ~1 × 10−10. Additionally, we provide a solid confirmation of the gauche isomer of ethyl mercaptan (g-C2H5SH) with an abundance of ~3 × 10−10, and we also detect methyl mercaptan (CH3SH) with an abundance of ~5 × 10−9. Abundance ratios were calculated for the three SH-bearing species and their OH analogs, revealing similar trends between alcohols and thiols with increasing complexity. Possible chemical routes for the interstellar synthesis of t-HC(O)SH, CH3SH, and C2H5SH are discussed, as well as the relevance of these compounds in the synthesis of prebiotic proteins in the primitive Earth.