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
Susana Iglesias-Groth
Summary: We used Spitzer Space Telescope spectra to search for the aromatic amino acid tryptophan in the interstellar gas of the young star cluster IC 348. We found emission lines in the observed spectrum that are consistent with the laboratory measurements of tryptophan. The presence of these lines in multiple interstellar locations suggests that the molecule causing the emission is widespread in interstellar space.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Athena R. Flint, Alexandria G. Watrous, Brent R. Westbrook, Dev J. Patel, Ryan C. Fortenberry
Summary: This study characterizes three derivatives in the dense interstellar medium, namely c-C-3(C2H)(2), c-C-3(CN)(2), and c-C-3(C2H)(CN), and establishes their potential for astrophysical observation. The results show that c-C-3(C2H)(2) and c-C-3(C2H)(CN) are viable candidates for detection, while c-C-3(CN)(2) is unlikely to be directly observable due to its small dipole moment.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
Marie Gueguen, Francois Lique
Summary: The detection and use of N+ ion as a tracer for atomic nitrogen in interstellar media make it an interesting ion from astrophysical perspective. Accurate determination of N+ abundance requires detailed modeling of its excitation conditions, which involves studying collisional excitation induced by dominant interstellar species. This paper investigates the collisional excitation of N+ by He and H-2, providing new potential energy surfaces and quantum calculations of excitation cross-sections and excitation rate coefficients. The results show that the excitation of N+ by a neutral collider can be significant in weakly ionized regions and warm molecular clouds.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Gwenaelle Dufour, Steven B. Charnley, Johan E. Lindberg
Summary: We study gas-grain chemical models of interstellar clouds to investigate non-linear dynamical evolution. We propose a method to produce oscillatory solutions in the presence of bistable solutions in gas-phase chemistry and demonstrate the existence of limit cycle and relaxation oscillation solutions. As these solutions are common to all models of interstellar chemistry, their occurrence should be widespread. We briefly discuss the implications for interpreting molecular cloud composition using time-dependent models and suggest some future directions for this approach.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Xia Zhang, Donghui Quan, Runxia Li, Jarken Esimbek, Long-Fei Chen, Guoming Zhao, Yan Zhou
Summary: Cyanamide and carbodiimide, which are considered key prebiotic molecules in the study of the origin of life, can form adenine in the interstellar medium (ISM) through a series of reactions. Using the NAUTILUS chemical code, we investigated their formation and destruction in different physical environments. Our simulated results indicate that these molecules primarily come from surface chemistry and are then released back to the gas phase. We speculate that forming a tautomer of adenine starting from cyanacetylene, cyanamide, and carbodiimide in ISM is an inefficient process.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Andre C. Souza, Mateus X. Silva, Breno R. L. Galvao
Summary: In this study, accurate multireference configuration interaction calculations were used to investigate the mechanisms and potential energy barriers of the N+PO and O+PN reactions. The interaction between atomic nitrogen and PO was found to occur barrierlessly only when dynamical correlation was included in the calculations. The results confirmed the assumptions in astrochemical models about the depletion of PO by nitrogen atoms and the preference for O+PN over the more exothermic P+NO reaction.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Boutheina Kerkeni, Victoria Gamez, Ghofrane Ouerfelli, Maria Luisa Senent, Nicole Feautrier
Summary: Both linear and branched isomers of propyl cyanide (PrCN; C3H7CN) are widely present in interstellar space as one of the most complex molecules found in the interstellar medium. The reaction mechanisms of radical-radical chemical reactions involving PrCN formation were studied using various quantum chemical methods. The results suggest efficient formation of both isomers on the ice model studied, with barrierless and exoergic reaction paths in both gas phase and on the ice mantle.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
S. Ferrero, F. Grieco, A-S Ibrahim Mohamed, F. Dulieu, A. Rimola, C. Ceccarelli, C. Nervi, M. Minissale, P. Ugliengo
Summary: This study investigates the binding energy of acetaldehyde in the interstellar medium and its potential freezing onto dust grains. The experiments and calculations show that the binding energy distribution of acetaldehyde on amorphous solid water ranges from 4000-6000 K. Comparison with other species indicates that acetaldehyde is less volatile than formaldehyde but more volatile than water, methanol, ethanol, and formamide.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Satyam Srivastav, Milan Sil, Prasanta Gorai, Amit Pathak, Bhalamurugan Sivaraman, Ankan Das
Summary: Straight-chain and branched-chain alkyl cyanides have been discovered in massive star-forming regions, indicating the presence of key amino acids in similar regions. The research shows that branching is more favorable for higher order alkyl cyanides, and realistic binding energy values can significantly change the abundance of these species.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Azrael A. von Prochazka, T. J. Millar
Summary: The study reveals that the abundances of NH3 in both gas phase and solid state are sensitive to gas-grain cycling within the system, and the degree of chemical complexity achievable at later stages of the cloud's chemical evolution is indeed influenced by the manner in which the gas-grain cycling occurs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
Article
Astronomy & Astrophysics
Danilo R. Campanha, Edgar Mendoza, Mateus X. Silva, Paulo F. G. Velloso, Miguel Carvajal, Valentine Wakelam, Breno R. L. Galvao
Summary: The impact of the Si + SO2 reaction on the abundances of astrochemically relevant molecules is investigated and it is found that only SO and SiO are produced as products. No other reaction pathways leading to the abundance of SiS have been identified. Furthermore, it is discovered that SiS is stable in collisions with O-2, and other reactions involving Si and S-bearing molecules are examined.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Ritika, T. J. Dhilip Kumar
Summary: This study investigates the non-reactive collisions between NCCP and He at low temperatures. The rotational cross-sections of NCCP-He collisions are calculated using a new ab initio potential energy surface. Resonances are observed at low energies due to quasi-bound states of the NCCP-IIe complex. The rate coefficients among the rotational levels of NCCP are determined by thermal averaging the cross-sections at low temperatures.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Zhisen Meng, Zhao Wang
Summary: The evolution of fullerenes in circumstellar envelopes has been studied through reactive molecular dynamics simulations. Different structures, such as onion-like nanostructures or single-layer fullerenes, are formed through heterogeneous reactions based on hydrogen concentration. Quantum chemical calculations show that as fullerenes grow larger, additional emission features are introduced in the infrared spectrum, and two-layered fullerenes exhibit noticeable blueshift or weakening effects on vibration modes.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Qingkuan Meng, Qiang Chang, Gang Zhao, Donghui Quan, Masashi Tsuge, Xia Zhang, Yong Zhang, Xiao-Hu Li
Summary: In this study, we quantitatively explain the relationship between the desorption energy of hydrogen on a diamond-like carbon surface and the surface coverage through experiments and calculations. We derived a mathematical formula to calculate the effective desorption energy of hydrogen, which depends on the desorption energy of hydrogen on the substrate and the ratio of diffusion barrier to desorption energy. By recalculating these parameters based on experimental data, we achieved good agreement between theoretical and experimental results.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)