Results 241 to 250 of about 2,384 (264)

Molecular clouds in galaxies with different Z - Fragmentation of diffuse clouds driven by opacity

Publications of the Astronomical Society of the Pacific, 1986
Molecular clouds are formed from diffuse interstellar clouds when the external ultraviolet radiation field is prevented from penetrating into the cloud. The opacity is provided mainly by dust grains and the required column density to the cloud center is larger than about 5 x 10 to the 20th (solar Z/Z)/sq cm.
Jose Franco, Donald P. Cox
exaly   +2 more sources

AMBIPOLAR DIFFUSION AND TURBULENT MAGNETIC FIELDS IN MOLECULAR CLOUDS

Modern Physics Letters A, 2011
We review the introduction and development of a novel method for the characterization of magnetic fields in star-forming regions. The technique is based on the comparison of spectral line profiles from coexistent neutral and ion molecular species commonly detected in molecular clouds, sites of star formation.
Houde, Martin, Hezareh, Talayeh, Li, Hua-Bai, Phillips, Thomas G.   +3 more
openaire   +2 more sources

Shocks in Diffuse and Dense Molecular Clouds

1988
The chemistry in postshock gas in interstellar clouds is particularly rich because reactions which are endothermic or which have activation barriers proceed more readily in gas heated to T ≳ 103 K than in cooler gas; in particular, the formation of sulfur-bearing and silicon-bearing species is efficient in postshock regions.
openaire   +1 more source

THE TRANSITION FROM DIFFUSE ATOMIC GAS TO MOLECULAR CLOUD IN TAURUS

Proceedings of the 74th International Symposium on Molecular Spectroscopy, 2019
We study four lines of sight that probe the transition from diffuse molecular gas to molecular cloud material in Taurus. Measurements of atomic and molecular absorption are used to infer the distribution of species and the physical conditions in the direction to stars behind the Taurus Molecular Cloud.
Federman, Steven, Rice, Johnathan S., Ritchey, Adam, Kim, Hwihyun, Lacy, John H., Goldsmith, Paul F., Flagey, Nicolas, Mace, Gregory N., Lambert, David L.   +8 more
openaire   +2 more sources

Cosmic-ray ionization in diffuse molecular clouds

AIP Conference Proceedings, 2018
Cosmic rays are believed to play an essential role in determining the chemistry and the evolution of molecular clouds. This is because they are usually considered to be the main ionization agent of these star-forming regions. We have recently studied such a hypothesis from a theoretical point of view for the case of diffuse molecular clouds using the ...
openaire   +2 more sources

MHD Shock Waves in Diffuse Molecular Clouds

1987
The theory of low-velocity (v s ≤ 30km/s) MHD shock waves in diffuse molecular gas is reviewed. The multifluid nature of the gas dynamics is emphasized, and the important microphysics and chemistry is mentioned. Recent attempts to use shock waves to account for the abundance of interstellar CH+ are discussed, and the required shock frequency and global
openaire   +1 more source

Extragalactic molecular clouds and chemistry of diffuse interstellar clouds

2009
openaire   +1 more source

Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope

Astronomy and Astrophysics, 2015
Peter Schilke, P Sonnentrucker, G Pineau Des Forêts   +2 more
exaly  

What causes the ionization rates observed in diffuse molecular clouds? The role of cosmic ray protons and electrons

Monthly Notices of the Royal Astronomical Society, 2018
Giovanni Morlino, S Gabici, Morlino G
exaly  

A search for diffuse gamma rays with energies above 1014 eV from molecular clouds in the galaxy

AIP Conference Proceedings, 1994
Matthews J, Covault C E, Sinclair D
exaly