Article
Astronomy & Astrophysics
Joshua T. Carder, Alec Paulive, Eric Herbst
Summary: The formation of complex organic molecules (COMs) in interstellar conditions is influenced by various processes in both the gas and solid phases. This study focuses on the influence of electronically excited metastable species on COM formation through insertion-type reactions. These reactions involve the insertion of a chemical entity into an existing chemical bond, allowing for rapid reactions even under cold, dark cloud conditions. The relative importance of this newly added process is evaluated by comparing it with existing suggested pathways.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Joshua T. Carder, Wyatt Ochs, Eric Herbst
Summary: The study explores the formation of complex organic molecules in interstellar space, focusing on reactions involving metastable oxygen atoms in the O(D-1) state. Specifically, the reactions of metastable oxygen atoms and methane in ices to form formaldehyde and methanol are examined, incorporating diffusive and non-diffusive chemistry processes. The contributions of O(D-1) at different temperatures are compared with traditional formation routes of methanol and formaldehyde.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2021)
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)
Article
Astronomy & Astrophysics
A. Megias, I Jimenez-Serra, J. Martin-Pintado, A. Vasyunin, S. Spezzano, P. Caselli, G. Cosentino, S. Viti
Summary: Recent observations of L1544 and L1498 show enhanced complex organic molecules (COMs) in the gas phase towards their outer and intermediate-density shells. High-sensitivity observations of L1517B reveal lower detection and abundance of COMs and COM precursors compared to L1544 and L1498. The chemical complexity in these starless cores seems to increase over time, with N-bearing molecules forming first followed by O-bearing COMs.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Long-Fei Chen, Qiang Chang, Yao Wang, Di Li
Summary: This study investigates the roles of stochastic grain heating in the formation of complex organic molecules (COMs) in cold cores. The research finds that grain coagulation can affect the formation of certain gas-phase species in cold core environments, and COMs formed on stochastically heated grains may help explain the observed abundances of gas-phase COMs in cold cores.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2022)
Article
Astronomy & Astrophysics
Johannes Heyl, Thanja Lamberts, Serena Viti, Jonathan Holdship
Summary: The impact of including reactions of C and CH with molecular hydrogen in a gas-grain network is evaluated through a sensitivity analysis. By varying the efficiency for the reaction, the cosmic ray ionization rate, and the final density of the collapsing dark cloud, a grid of 12 models is used to investigate the effect of these parameters on the final molecular abundances of the chemical network. It is found that including reactions with molecular hydrogen alters the hydrogen economy of the network, leading to changes in the abundances of different species.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Lisa Giani, Cecilia Ceccarelli, Luca Mancini, Eleonora Bianchi, Fernando Pirani, Marzio Rosi, Nadia Balucani
Summary: This article presents a revised reaction network for the formation of methyl cyanide in the gas phase and explores the chemical link between methyl cyanide and methanol. The study identifies two new reactions that play a significant role in the formation of methyl cyanide and confirms the importance of a radiative association and electron recombination reaction in both cold and warm environments.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Kin Long Kelvin Lee, P. Bryan Changala, Ryan A. Loomis, Andrew M. Burkhardt, Ci Xue, Martin A. Cordiner, Steven B. Charnley, Michael C. McCarthy, Brett A. McGuire
Summary: Using radio observations with the Green Bank Telescope, evidence has been found for a second five-membered ring in the dense cloud Taurus Molecular Cloud-1 (TMC-1). Through additional observations, improved detection significance for the more stable isomer and evidence for several individual transitions between 23-32 GHz were obtained. The derived abundance ratios suggest a common formation pathway involving cyanation of cyclopentadiene by analogy to benzonitrile.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
A. Clement, A. Taillard, V. Wakelam, P. Gratier, J. -c. Loison, E. Dartois, F. Dulieu, J. A. Noble, M. Chabot
Summary: This study models the formation process of interstellar ices, focusing on H2O, CO2, CO, and CH3OH. The research finds that dust temperature and visual extinction significantly influence the composition of ice, with the formation of CO2 being particularly affected by dust temperature under low visual extinction conditions.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
J. Garcia de la Concepcion, I. Jimenez-Serra, J. C. Corchado, G. Molpeceres, A. Martinez-Henares, V. M. Rivilla, L. Colzi, J. Martin-Pintado
Summary: This study investigates the difference in abundance ratios between isomers of an organic molecule in the interstellar medium (ISM) and provides valuable information about the chemistry, physics, and history of molecular clouds. The presence of cis-formic acid (c-HCOOH) at only 6% abundance compared to the trans isomer (t-HCOOH) in cold cores is explained through a cyclic process involving HCOOH, HCO+, and NH3. The proposed sequential acid-base (SAB) mechanism is a new approach to understanding the isomerism of organic molecules in the ISM.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
H. Luthra, V Wakelam, M. K. Sharma, S. Chandra
Summary: Since the 1930s, more than 250 molecules have been discovered in the interstellar medium, and with the development of more sensitive telescopes, we keep detecting new, more complex species. Among them, methanimine (CH2NH) is considered a pre-biotic molecule and has been observed in various interstellar sources. However, previous models failed in reproducing the observed abundance of CH2NH in cold cores. In this study, we tested new proposed reactions and explored the sensitivity of CH2NH abundance to different factors, and successfully reproduced the detections in cold cores Ori-3N and L183.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Tadeus Carl, E. S. Wirstrom, P. Bergman, S. B. Charnley, Y-L Chuang, Y-J Kuan
Summary: One of the fundamental hypotheses in astrochemistry and astrobiology suggests that biotic molecules like glycine found in meteorites and comets are inherited from early star formation phases. Recent studies propose shifting the observational focus to cold low-mass sources in order to detect glycine. The study conducted deep pointed observations and derived sensitive abundance upper limits for glycine conformers I and II towards the methanol hotspot in the Barnard 5 dark cloud.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Katherine Rawlins, Bhaswati Mookerjea
Summary: We study the correlation between OH and H-2 column densities in diffuse Galactic clouds to find potential molecular tracers of interstellar H-2. Analysis of near-UV spectra from the ESO/VLT archives reveals a marginal correlation between N (OH) and N (H-2) at the 95% confidence level. Orthogonal distance regression analysis gives N (OH) /N (H-2) = (1.32 ± 0.15) x 10^-7, which is approximately 33% higher than previous estimates. We also find a significant correlation between N (OH) and N (CH), both consistent with previous results.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
J. Garcia de la Concepcion, I. Jimenez-Serra, V. M. Rivilla, L. Colzi, J. Martin-Pintado
Summary: The formation of polycyclic aromatic hydrocarbons (PAHs) in the interstellar medium has been a topic of interest for astrophysicists. Through simulated reactions in molecular clouds, it was found that the reaction between the propargyl radical and the vinyl radical may occur under interstellar conditions, yielding the cyclopentadienyl radical, which could be an important precursor for the formation of more complex polycyclic hydrocarbons and simple PAHs.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Astronomy & Astrophysics
O. Sipilae, L. Colzi, E. Roueff, P. Caselli, F. Fontani, E. Wirstroem
Summary: In this study, a new gas-grain chemical model for the combined isotopic fractionation of carbon and nitrogen in molecular clouds is presented. The results show significant deviations and time-dependent variations in isotopic abundance ratios as a function of physical conditions and time. Additionally, the abundance ratios between different isotopic forms of molecules also exhibit some levels of fractionation due to newly included exchange reactions.
ASTRONOMY & ASTROPHYSICS
(2023)
Article
Chemistry, Physical
Marie-Aline Martin-Drumel, Michael C. McCarthy, David Patterson, Brett A. McGuire, Kyle N. Crabtree
JOURNAL OF CHEMICAL PHYSICS
(2016)
Article
Chemistry, Physical
Michael C. McCarthy, Oscar Martinez, Brett A. McGuire, Kyle N. Crabtree, Marie-Aline Martin-Drumel, John F. Stanton
JOURNAL OF CHEMICAL PHYSICS
(2016)
Article
Astronomy & Astrophysics
A. M. Burkhardt, E. Herbst, S. V. Kalenskii, M. C. McCarthy, A. J. Remijan, B. A. McGuire
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2018)
Article
Chemistry, Physical
Brett A. McGuire, Marie-Aline Martin-Drumel, Kin Long Kelvin Lee, John F. Stanton, Carl A. Gottlieb, Michael C. McCarthy
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2018)
Article
Multidisciplinary Sciences
Brett A. McGuire, Andrew M. Burkhardt, Sergei Kalenskii, Christopher N. Shingledecker, Anthony J. Remijan, Eric Herbst, Michael C. McCarthy
Article
Astronomy & Astrophysics
Andrew M. Burkhardt, Christopher N. Shingledecker, Romane Le Gal, Brett A. McGuire, Anthony J. Remijan, Eric Herbst
ASTROPHYSICAL JOURNAL
(2019)
Article
Chemistry, Physical
Kin Long Kelvin Lee, Brett A. McGuire, Michael C. McCarthy
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2019)
Article
Astronomy & Astrophysics
Adam Ginsburg, Brett McGuire, Richard Plambeck, John Bally, Ciriaco Goddi, Melvyn Wright
ASTROPHYSICAL JOURNAL
(2019)
Article
Astronomy & Astrophysics
Brett A. McGuire, Andrew M. Burkhardt, Christopher N. Shingledecker, Sergei V. Kalenskii, Eric Herbst, Anthony J. Remijan, Michael C. McCarthy
ASTROPHYSICAL JOURNAL LETTERS
(2017)
Article
Astronomy & Astrophysics
M. A. Cordiner, S. B. Charnley, Z. Kisiel, B. A. McGuire, Y. -J. Kuan
ASTROPHYSICAL JOURNAL
(2017)
Article
Astronomy & Astrophysics
Brett A. McGuire, Christopher N. Shingledecker, Eric R. Willis, Andrew M. Burkhardt, Samer El-Abd, Roman A. Motiyenko, Crystal L. Brogan, Todd R. Hunter, Laurent Margules, Jean-Claude Guillemin, Robin T. Garrod, Eric Herbst, Anthony J. Remijan
ASTROPHYSICAL JOURNAL LETTERS
(2017)
Article
Chemistry, Physical
Brett A. McGuire, Marie-Aline Martin-Drumel, Michael C. McCarthy
JOURNAL OF PHYSICAL CHEMISTRY A
(2017)
Article
Astronomy & Astrophysics
A. P. M. Towner, C. L. Brogan, T. R. Hunter, C. J. Cyganowski, B. A. McGuire, R. Indebetouw, R. K. Friesen, C. J. Chandler
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2017)
Article
Astronomy & Astrophysics
Brett A. McGuire
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2018)
Article
Astronomy & Astrophysics
Brett A. McGuire, Crystal L. Brogan, Todd R. Hunter, Anthony J. Remijan, Geoffrey A. Blake, Andrew M. Burkhardt, P. Brandon Carroll, Ewine F. van Dishoeck, Robin T. Garrod, Harold Linnartz, Christopher N. Shingledecker, Eric R. Willis
ASTROPHYSICAL JOURNAL LETTERS
(2018)
