Results 11 to 20 of about 470 (131)

First Principles Rovibronic Absorption Spectra of HF Molecule. [PDF]

J Comput Chem
Hydrogen fluoride (HF) is astrophysically important, as it has been detected in sunspots, Venus, red giants, and the interstellar medium, serving as a probe of exoplanet atmospheres. This article presents an ab initio investigation of HF rovibronic spectroscopy, combining high‐level electronic‐structure data with nuclear‐motion solutions and refinement
Abu El Kher N, Shibli M, Korek M, Yurchenko SN, Tennyson J, El-Kork N.   +5 more
europepmc   +2 more sources

Mid-infrared Spectroscopy of Protonated Benzonitrile, 2-Cyanonaphthalene, and 9-Cyanoanthracene for Astrochemical Consideration. [PDF]

Chemphyschem
Experimental infrared absorption spectra of three protonated cyano‐substituted PAHs measured by infrared multiple photon dissociation using the free‐electron laser Free‐Electron Laser for Infrared eXperiments are studied. These spectra are compared to an emission spectrum measured by JWST, and the largest measured protonated cyano‐PAH, cyanoanthracene,
Rasmussen AP, Rossi C, Gans B, Finazzi L, Oomens J, Berden G, Jacovella U.   +6 more
europepmc   +2 more sources

Abundances in Diffuse Interstellar Clouds [PDF]

Highlights of Astronomy, 1980
Interstellar clouds are concentrations of cold (T ≲ 100 K) neutral gas (cf. Spitzer 1978) which are immersed within an intercloud medium. It is worthwhile to distinguish between diffuse clouds (roughly those with E[B-V] ≳ 0.5) and dark clouds (those with E[B-V] ≳ 0.5). This distinction is useful in the sense that diffuse clouds are relatively warm (T ∼
openaire   +1 more source

Atomistic Modeling of Methyl Formate and Glycolaldehyde Formation on Interstellar Dirty Ice Mantles via a "Radical + Ice" Mechanism. [PDF]

Chempluschem
The presence of interstellar complex organic molecules (COMs) has been baffling astrochemists for a long time. Methyl formate and glycolaldehyde are widely detected but their abundances mismatch kinetic astrochemical model predictions. Here, the formation of these two COMs is characterized onto a mixed ice surface, highlighting the importance of ...
Perrero J, Pantaleone S, Ugliengo P, Rimola A.   +3 more
europepmc   +2 more sources

Shocks and Molecules in Diffuse Interstellar Cloud Pairs [PDF]

The Astrophysical Journal, 2021
Abstract The diffuse interstellar medium (ISM) is dynamic, and its chemistry and evolution are determined by shock fronts as well as photodissociation. Shocks are implied by the supersonic motions and velocity dispersion, often statistically called “turbulence”.
William T. Reach, Carl Heiles
openaire   +2 more sources

Diffuse interstellar clouds associated with dark clouds

The Astrophysical Journal, 1982
Measurements of CH emission at 9 cm toward the bright stars ..cap alpha.. Cam and kappa Cas and from dark clouds near the stars reveal an association between diffuse clouds and dark clouds. Here the term diffuse clouds refers to clouds seen in optical absorption; the term dark clouds refers to opaque regions on the Palomar Sky Survey observed through ...
S. R. Federman, R. F. Willson
openaire   +1 more source

The Smallest Sizes of Diffuse Interstellar Clouds [PDF]

International Astronomical Union Colloquium, 1984
AbstractBy observing the difference in optical depths between absorption spectra toward the two components of double sources we have measured the variations in opacity over lengths of less than 0.1 up to 10 pc inside diffuse interstellar clouds. Significant variations are detected on scales larger than about 0.2 pc, but not less. This may represent the
John M. Dickey, J. Crovisier, I. Kazes
openaire   +1 more source

The formation of molecules in diffuse interstellar clouds

The Astrophysical Journal, 1977
A chemical system involving carbon and hydrogen is used to obtain steady-state abundances of a number of molecules over a wide range of densities. The calculated CH abundance agrees well with the astronomical observations. For reasonable values of the rate coefficients, the present system of reactions cannot explain, simultaneously, the measured ...
G. F. Mitchell, P. J. Kuntz, J. L. Ginsburg   +2 more
openaire   +1 more source

EXCITATION OF C₂IN DIFFUSE INTERSTELLAR CLOUDS

The Astrophysical Journal, 2012
We investigate the effects and the implications of incorporating new collision and radiative rates in modeling the excitation of diatomic carbon molecule. The present results suggest that diffuse and translucent interstellar clouds may present a structure in which regions with different densities and kinetic temperatures overlap along the line of sight,
S. Casu, Cesare Cecchi-Pestellini
openaire   +2 more sources

On the detection of rubidium in diffuse interstellar clouds

The Astrophysical Journal, 1985
A search for absorption from neutral rubidium at 7800 A was conducted. No evidence for absorption to a 3 sigma limit of less than 1.5 mA was seen in the diffuse interstellar gas toward the stars omicron Persei, zeta Persei, and zeta Ophiuchi. Present results do not confirm the detection by Jura and Smith (1981) toward zeta Oph.
S. R. Federman, C. Sneden, W. V. Schempp, W. H. Smith   +3 more
openaire   +1 more source