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Related papers: Rotational equilibrium of C$_2$ in diffuse interst…

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We present a semi-analytical description of the relative HD/H2 abundance in the diffuse interstellar medium. We found three asymptotics of the relative HD/H$_2$ abundance for different parts of the medium and their dependence on the…

Astrophysics of Galaxies · Physics 2020-01-15 S. A. Balashev , D. N. Kosenko

C$_2$H is one of the first radicals to be detected in the interstellar medium. Its higher rotational transitions have recently become available with the Herschel Space Observatory. We aim to constrain the physical parameters of the C$_2$H…

Astrophysics of Galaxies · Physics 2015-06-17 Z. Nagy , V. Ossenkopf , F. F. S. Van der Tak , A. Faure , Z. Makai , E. A. Bergin

Recent astronomical observations revealed an increasing molecular complexity in the interstellar medium through the detection of a series of large cyclic carbon species. To correctly interpret these detections, a complex analysis is…

Atomic and Molecular Clusters · Physics 2024-06-05 Sándor Demes , Cheikh Tidiane Bop , Malek Ben Khalifa , François Lique

Experimental measurements and theoretical calculations of state-to-state rate coefficients for rotational energy transfer of CO in collision with H$_2$ are reported at the very low temperatures prevailing in dense interstellar clouds (5 -…

Photodissociation regions (PDRs) and shocks give rise to conspicuous emission from rotationally and vibrationally excited molecular hydrogen. This line emission has now been studied with ISO and from the ground in great detail. A remarkable…

We combine experimental and theoretical approaches to explore excited rotational states of molecules embedded in helium nanodroplets using CS$_2$ and I$_2$ as examples. Laser-induced nonadiabatic molecular alignment is employed to measure…

We present the detection and analysis of molecular hydrogen emission toward ten interstellar regions in the Large Magellanic Cloud. We examined low-resolution infrared spectral maps of twelve regions obtained with the Spitzer infrared…

We have performed a series of calculations designed to reproduce infrared diagnostics used to determine physical conditions in star forming regions. We self-consistently calculate the thermal and chemical structure of an H II region and…

Astrophysics · Physics 2009-11-11 N. P. Abel , G. J. Ferland , G. Shaw , P. A. M. van Hoof

We combine recent ISO observations of the vibrational ground state lines of H2 towards Photon-Dominated Regions (PDRs) with observations of vibrationally excited states made with ground-based telescopes in order to constrain the formation…

Astrophysics · Physics 2009-11-10 E. Habart , F. Boulanger , L. Verstraete , C. M. Walmsley , G. Pineau des Forets

We report results from a FUSE survey of interstellar molecular hydrogen (H2) in the Galactic disk toward 139 O-type and early B-type stars at Galactic latitudes $|b| < 10^{\circ}$, with updated photometric and parallax distances. The H2…

Astrophysics of Galaxies · Physics 2021-04-21 J. Michael Shull , Charles W. Danforth , Katherine L. Anderson

The addition of individual quanta of rotational excitation to a molecule has been shown to markedly change its reactivity by significantly modifying the intermolecular interactions. So far, it has only been possible to observe these…

Chemical Physics · Physics 2024-03-06 Jutta Toscano

The availability of collisional rate coefficients with H$_2$ is a pre-requisite for interpretation of observations of molecules whose energy levels are populated under non local thermodynamical equilibrium conditions. In the current study,…

Astrophysics of Galaxies · Physics 2015-06-22 F. Daniel , A. Faure , L. Wiesenfeld , E. Roueff , D. C. Lis , P. Hily-Blant

The synergy between high-resolution rotational spectroscopy and quantum-chemical calculations is essential for exploring future detection of molecules, especially when spectroscopy parameters are not available yet. By using highly…

Instrumentation and Methods for Astrophysics · Physics 2023-11-16 Natalia Inostroza-Pino , Valerio Lattanzi , C. Zachary Palmer , Ryan C. Fortenberry , Diego Mardones , Paola Caselli , Oko E. Godwin , Timothy J. Lee

We introduce a sub-grid model for the non-equilibrium abundance of molecular hydrogen in cosmological simulations of galaxy formation. We improve upon previous work by accounting for the unresolved structure of molecular clouds in a…

Astrophysics of Galaxies · Physics 2015-06-19 Matteo Tomassetti , Cristiano Porciani , Emilio Romano-Diaz , Aaron D. Ludlow

Only a few weakly-bound complexes containing the O2 molecule have been characterized by high resolution spectroscopy, no doubt due to the complications added by the oxygen molecule's unpaired electron spin. Here we report an extensive…

Atomic and Molecular Clusters · Physics 2018-07-04 A. J. Barclay , A. R. W. McKellar , N. Moazzen-Ahmadi , Richard Dawes , Xiao-Gang Wang , Tucker Carrington

Collisional (de-)excitation of H$_{2}$ by helium plays an important role in the thermal balance and chemistry of various astrophysical environments, making accurate rate coefficients essential for the interpretation of observations of the…

Astrophysics of Galaxies · Physics 2024-05-15 Hubert Jóźwiak , Franck Thibault , Alexandra Viel , Piotr Wcisło , François Lique

A model of the collisional kinetics of energetic hydrogen atoms, molecules, and ions in pure H$_2$ discharges is used to predict H$_\alpha$ emission profiles and spatial distributions of emission from the cathode regions of low-pressure,…

Plasma Physics · Physics 2015-05-20 A. V. Phelps

The rate constants for the formation, destruction, and collisional excitation of SH$^+$ are calculated from quantum mechanical approaches using two new SH$_2^+$ potential energy surfaces (PESs) of $^4A''$ and $^2A''$ electronic symmetry.…

Astrophysics of Galaxies · Physics 2019-06-26 Alexandre Zanchet , Francois Lique , Octavio Roncero , Javier R. Goicoechea , Niyazi Bulut

JWST is discovering a plethora of species in planet-forming disks around very low-mass stars such as C2H2, C6H6, C4H2, CH3 etc. The column densities of these species retrieved from 0D slab models are very large, e.g. of the order of…

We aim to investigate the chemistry of internal photon-dominated regions surrounding deeply embedded hypercompact and ultracompact HII regions. We search for specific tracers of this evolutionary stage of massive star formation that can be…