Article
Astronomy & Astrophysics
N. Tieppo, F. Pauzat, O. Parisel, Y. Ellinger
Summary: This study finds that in the interstellar medium, the conversion of CO to CH3OH can occur without any energy barriers when using [H...(H2O)(n)] complexes as hydrogenation vectors on water ice surfaces. This simplified synthetic approach could be generalized for studying important atomic hydrogenations on ices in the interstellar medium.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Akant Vats, Amit Pathak
Summary: The detection of benzonitrile and cyano-naphthalene in the cold, dark molecular cloud TMC-1 has opened up possibilities for the detection of other N- and CN-containing polycyclic aromatic hydrocarbons (PAHs). This study presents the rotational spectra of N-pyrene, CN-pyrene, N-coronene, and CN-coronene for the first time. The density functional theory calculations achieved the best performance in determining the spectroscopic parameters and simulating the rotational spectra. The large permanent dipole moment of CN-PAHs makes them suitable for detection in the interstellar medium, and CN-pyrene is a potential candidate to be discovered in cold, dark molecular clouds. This work provides a benchmark for the theoretical rotational spectra of N- and CN-containing PAHs and can guide laboratory experiments and observational searches.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
E. Roueff, M. G. Burton, T. R. Geballe, H. Abgrall
Summary: A study has identified highly excited molecular hydrogen in a spectrum and found the presence of a hot thermal component at 5000K, indicating dissociation of H-2 is occurring.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Agundez, C. Cabezas, N. Marcelino, R. Fuentetaja, B. Tercero, P. de Vicente, J. Cernicharo
Summary: The presence of two species related to the nonpolar molecule cyanogen (NCCN) in cold dense clouds had led to the hypothesis that dicyanopolyynes are abundant in space. In this study, the first identification of NC4NH+ in space is reported. The detection was based on the observation of six harmonically related lines within the Yebes 40m line survey of TMC-1 QUIJOTE. High-level ab initio calculations supported the identification of NC4NH+.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
M. Agundez, C. Cabezas, N. Marcelino, R. Fuentetaja, B. Tercero, P. de Vicente, J. Cernicharo
Summary: In recent years, there has been an increase in the detection of protonated molecules in cold dense clouds. The study reports the detection of HCCNCH+ in TMC-1, which is the protonated form of a metastable isomer of HC3N. The findings suggest a correlation between the presence of protonated molecules in cold dense clouds and their proton affinity.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
C. Cabezas, M. Agundez, N. Marcelino, B. Tercero, S. Cuadrado, J. Cernicharo
Summary: The study reports the first identification of H2NC in space, an isomer of H2CN, with detailed observations in cold dark clouds. The abundance ratio of H2NC/H2CN varies in different clouds, suggesting potential production mechanisms involving N+CH3 and C+NH3 reactions. Further research is required to understand the chemistry behind H2NC and the implications of its ratio with H2CN in different interstellar environments.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
M. Agundez, N. Marcelino, C. Cabezas, R. Fuentetaja, B. Tercero, P. de Vicente, J. Cernicharo
Summary: We reported the detection of the propargyl radical (CH2CCH) in the cold dark cloud TMC-1 in the lambda 3 mm wavelength band. The observed frequencies differed from the predictions by 0.2 MHz, which is significant for radioastronomical searches. The study provides accurate frequency predictions and recommends future searches to be conducted in the lambda 3 mm band.
ASTRONOMY & ASTROPHYSICS
(2022)
Article
Astronomy & Astrophysics
M. Agundez, C. Cabezas, B. Tercero, N. Marcelino, J. D. Gallego, P. de Vicente, J. Cernicharo
Summary: The propargyl radical CH2CCH was detected for the first time in interstellar space, showing similar abundance to methyl acetylene and potentially playing a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.
ASTRONOMY & ASTROPHYSICS
(2021)
Article
Astronomy & Astrophysics
F. D. Priestley, A. P. Whitworth
Summary: Research suggests that collisions between interstellar gas clouds can rapidly generate large masses of dense gas, triggering star formation. By analyzing molecular line observations and conducting simulations, it is possible to distinguish genuinely colliding clouds from chance superpositions, and confirm observational evidence of cloud collisions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
F. D. Priestley, D. Arzoumanian, A. P. Whitworth
Summary: Filamentary structures in molecular clouds, which are important for star formation, are expected to form where the supersonic turbulent velocity field converges. While the existing model reproduces some properties of these structures, it is unclear whether it can reproduce their kinematic features. In this study, we use modeling to predict the emission properties of dynamically forming filaments, and the results are largely consistent with observations, suggesting that equilibrium analysis and simulations assuming the existence of filaments may be unrealistic.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Neubi F. Xavier, Antonio M. da Silva, Marco Sacchi, Glauco F. Bauerfeldt
Summary: In this study, the decarboxylation mechanism of glycine on a water-rich surface and on a glycine ice was simulated using density functional theory. The results show that the decomposition of glycine into CO2 and CH3NH2 is thermodynamically controlled in specific interstellar regions.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Gang Zhao, Qiang Chang, Xia Zhang, Donghui Quan, Yong Zhang, Xiao-Hu Li
Summary: This study investigates the impact of hydrogen molecules on grain surfaces on the efficiency of H-2 formation in diffuse and translucent clouds. The diffusion barriers of H(2) on grain surfaces play a significant role in determining the influence of surface H(2) on H(2) formation efficiency. The recombination efficiency of H atoms in diffuse cloud models without surface H(2) is predicted to be above 0.5 over a temperature range of 10 to 14 K. However, in diffuse cloud models considering surface H(2), the recombination efficiency varies between nearly 0 and 0.5 at temperatures of 10 <= T <= 14 K, depending on model parameters. Translucent cloud models show that the existence of surface H(2) does not impact H(2) formation efficiency if the average H(2) diffusion barrier on grain surfaces is low (194 K). However, if a higher average H(2) diffusion barrier is used (255 K), the recombination efficiency can drop to below 0.002 at T >= 10 K.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Giuseppe Cassone, Franz Saija, Jiri Sponer, Judit E. Sponer, Antonio Jimenez-Escobar, Angela Ciaravella, Cesare Cecchi-Pestellini
Summary: The article investigates the role of ice in shaping the free-energy landscape of selected reactions using advanced molecular dynamics techniques. Ice acts not only as a gatherer of reactants, but also creates thermodynamic conditions favoring chemical evolution.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Hexu Ye, Silvia Alessandrini, Cristina Puzzarini
Summary: Sulphur is an important and ubiquitous element in the interstellar medium. This study finds that the reaction between H2CS and OH can produce isomers belonging to the CH2SO family, including trans-HC(S)OH and trans-HC(O)SH. The detection of trans-HC(O)SH suggests that trans-HC(S)OH is a promising candidate for astronomical observations.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. A. M. Paiva, S. Pilling, E. Mendoza, B. R. L. Galvao, H. A. De Abreu
Summary: This study explores a new gas-phase mechanism for the formation of glycolaldehyde and compares the reduction of energy barriers on amorphous ice surfaces. The average reduction of the energy barrier is found to be 49%, with some cases showing a 100% reduction. The adsorption energy of glycolaldehyde suggests its prompt desorption to the gas phase after formation. This work contributes to explaining the relative abundances of glycolaldehyde and provides a new methodological framework for studying the formation routes of complex organic molecules in interstellar icy grains.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
G. Quintana-Lacaci, L. Velilla-Prieto, M. Agundez, J. P. Fonfria, J. Cernicharo, L. Decin, A. Castro-Carrizo
Summary: This study presents high angular resolution interferometric ALMA maps of VY CMa continuum and molecular emission, revealing the structure and different types of ejecta. The results suggest that two different mass loss processes occur in this massive star. These findings provide essential information for understanding the mass loss processes and further evolution of red supergiants.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Chemistry, Physical
E. M. Roueff, H. Abgrall
Summary: In this study, the radiative ro-vibrational emission spectrum of H-2 involving quasi-bound states is calculated using a simple numerical method, in which a modified effective molecular potential is introduced. The obtained eigenvalues are compared with those obtained from other theoretical methods based on scattering resonance properties, showing excellent agreement. The contributions of electric quadrupole and magnetic dipole are also calculated, confirming previous computations of electric quadrupole transition Einstein coefficients by Forrey. The astrophysical relevance of these quasi-bound levels is highlighted.
Article
Astronomy & Astrophysics
M. Agundez, C. Cabezas, N. Marcelino, R. Fuentetaja, B. Tercero, P. de Vicente, J. Cernicharo
Summary: The presence of two species related to the nonpolar molecule cyanogen (NCCN) in cold dense clouds had led to the hypothesis that dicyanopolyynes are abundant in space. In this study, the first identification of NC4NH+ in space is reported. The detection was based on the observation of six harmonically related lines within the Yebes 40m line survey of TMC-1 QUIJOTE. High-level ab initio calculations supported the identification of NC4NH+.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Mathilde Gaudel, Jan H. Orkisz, Maryvonne Gerin, Jerome Pety, Antoine Roueff, Antoine Marchal, Francois Levrier, Marc-Antoine Miville-Deschenes, Javier R. Goicoechea, Evelyne Roueff, Franck Le Petit, Victor de Souza Magalhaes, Pierre Palud, Miriam G. Santa-Maria, Maxime Vono, Sebastien Bardeau, Emeric Bron, Pierre Chainais, Jocelyn Chanussot, Pierre Gratier, Viviana Guzman, Annie Hughes, Jouni Kainulainen, David Languignon, Jacques Le Bourlot, Harvey Liszt, Karin Oberg, Nicolas Peretto, Albrecht Sievers, Pascal Tremblin
Summary: In this study, observations of star-forming material were conducted using the Regularized Optimization for Hyper-Spectral Analysis algorithm. The results showed that the feedback from star-forming material is crucial in the formation of filamentary structures.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
E. Roueff, M. G. Burton, T. R. Geballe, H. Abgrall
Summary: A study has identified highly excited molecular hydrogen in a spectrum and found the presence of a hot thermal component at 5000K, indicating dissociation of H-2 is occurring.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Carlos Cabezas, Isabel Pena, Jose Cernicharo
Summary: The recent detection of cyanonaphthalenes in interstellar space has sparked interest in exploring other aromatic molecular species that may be present in similar environments. This study focuses on ethynyl derivatives of naphthalene as potential candidates to be observed in the Taurus Molecular Cloud (TMC-1), where cyanonaphthalenes, as well as cyano- and ethynyl-derivatives of cyclopentadiene and benzene, have already been found. The researchers have successfully observed the rotational spectra of 1- and 2-ethynylnaphthalene species for the first time, providing accurate spectroscopic parameters that will aid in future astronomical searches.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
M. Agundez, J. -c. Loison, K. M. Hickson, V. Wakelam, R. Fuentetaja, C. Cabezas, N. Marcelino, B. Tercero, P. de Vicente, J. Cernicharo
Summary: We detected the presence of ethanol, acetone, and propanal in the cyanopolyyne peak of TMC-1, which are complex organic molecules known to be present in warm interstellar clouds but had never been observed in a starless core. This discovery adds new pieces to the puzzle of complex organic molecules in cold interstellar clouds, highlighting the chemical diversity of cold dense cores prior to star formation. The abundances of these molecules derived from observations are in reasonable agreement with the values calculated by a detailed chemical model.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Alexander M. Mebel, Marcelino Agundez, Jose Cernicharo, Ralf I. Kaiser
Summary: The recent detection of ethynylbutatrienylidene (HCCCHCCC) and hexapentaenylidene (H2CCCCCC) in TMC-1, high-energy isomers of hydrocarbons, puzzled scientists as the proposed reaction pathways could not explain their presence under cold molecular cloud conditions. However, through detailed studies, it was revealed that the reaction between tricarbon (C-3) and the propargyl radical (C3H3) after a few 10(5) years can quantitatively replicate the observed fractional abundance of ethynylbutatrienylidene (HCCCHCCC). This study provides convincing evidence that previously assumed dead reactants play a crucial role in the growth of molecules in cold molecular clouds, leading to the formation of exotic high-energy isomers.
ASTROPHYSICAL JOURNAL LETTERS
(2023)
Article
Chemistry, Physical
Jacques Le Bourlot, Evelyne Roueff, Franck Le Petit, Florian Kehrein, Annika Oetjens, Holger Kreckel
Summary: The triatomic hydrogen ion H-3(+) is significant for interstellar gas phase chemistry and used to determine interstellar parameters. Previous attempts failed to explain the temperature difference between H-3(+) and H-2 observations. New studies show that the formation reaction affects H-3(+) populations and incomplete thermal equilibrium occurs before its destruction by free electrons. Considering multiple levels of H-3(+) and including radiative transitions and collisions with H-2 in models leads to good agreement with observational data.
Article
Astronomy & Astrophysics
Carlos Cabezas, Marcelino Agundez, Yi-Ting Liu, Yasuki Endo, Jose Cernicharo
Summary: The interstellar discovery of the five cyano derivatives of propene has sparked interest in similar molecules that could be found in similar astronomical environments. The study focuses on the ethynyl-propene derivatives as potential candidates for detection in the Taurus Molecular Cloud (TMC-1), where other cyano and ethynyl derivatives of hydrocarbons have already been detected. The researchers have investigated the rotational spectra of these ethynyl-propene derivatives to facilitate their detection in interstellar environments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Spectroscopy
Carlos Cabezas, Yoshiyuki Kawashima, Celina Bermudez, Tsuyoshi Usami, Eizi Hirota, Jose Cernicharo
Summary: A molecule containing a peptide linkage -(C--O)NH- called N-ethylformamide was studied using rotational spectroscopy to determine the molecular constants of its highest-energy conformer, cis-ac. The rotational spectrum of the molecule was observed in two different frequency ranges using different spectrometers. Thirteen molecular constants were determined from the observational data, providing a more accurate spectral model for the cis-ac conformer and serving as a basis for its astronomical search.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2023)
Article
Astronomy & Astrophysics
M. Agundez, N. Marcelino, B. Tercero, I. Jimenez-Serra, J. Cernicharo
Summary: In this study, new observations of interstellar molecular anions were presented and used to model their excitation and abundances. The results showed that the anion-to-neutral ratios were consistent with literature values and increased with molecular size. However, the collision rate coefficients for some species need to be reevaluated.
ASTRONOMY & ASTROPHYSICS
(2023)