Magnetohydrodynamic shocks in diffuse clouds. II - Production of CH(+), OH, CH, and other species

1986 ◽  
Vol 310 ◽  
pp. 392 ◽  
Author(s):  
B. T. Draine ◽  
Neal Katz
Keyword(s):  
Diffuse Clouds ◽  
Magnetohydrodynamic Shocks

scholarly journals Detection of Magnetohydrodynamic Shocks in the L1551 Outflow

1994 ◽  
Vol 140 ◽  
pp. 222-223
Author(s):  
M. Barsony ◽  
N. Z. Scoville ◽  
C. J. Chandler
Keyword(s):  
Near Infrared ◽  
Resolution Single ◽  
Shock Fronts ◽  
Magnetohydrodynamic Shocks

AbstractWe report the results of CO J=l—+0 mapping of portions of the blue outflow lobe of L1551 with ~ 7” (N-S) × 4” (E-W) resolution, obtained with the 3-element OVRO millimeter array. Comparison of our interferometer mosaic with lower resolution single-dish data shows that we resolve the strongest single-dish emission regions into filamentary structures, such as are characteristic of shock fronts mapped via their near-infrared H2 emission in other outflow sources.

scholarly journals Search for C2−in Diffuse Clouds

2005 ◽  
Vol 57 (4) ◽  
pp. 605-609 ◽  
Author(s):  
Svatopluk Civiš ◽  
Yukio Hosaki ◽  
Eriko Kagi ◽  
Hideyuki Izumiura ◽  
Kenshi Yanagisawa ◽  
...  
Keyword(s):  
Diffuse Clouds

Stability of Plane Magnetohydrodynamic Shocks

1964 ◽  
Vol 7 (5) ◽  
pp. 700 ◽  
Author(s):  
C. S. Gardner ◽  
M. D. Kruskal
Keyword(s):  
Magnetohydrodynamic Shocks

scholarly journals Effects of turbulent diffusion on the chemistry of diffuse clouds

2007 ◽  
Vol 469 (3) ◽  
pp. 949-961 ◽  
Author(s):  
P. Lesaffre ◽  
M. Gerin ◽  
P. Hennebelle
Keyword(s):  
Turbulent Diffusion ◽  
Diffuse Clouds

scholarly journals Abundances in Diffuse Interstellar Clouds

1980 ◽  
Vol 5 ◽  
pp. 293-300 ◽  
Author(s):  
M. Jura
Keyword(s):  
Interstellar Extinction ◽  
Future Research ◽  
Chemical Compositions ◽  
Interstellar Clouds ◽  
Dark Clouds ◽  
Neutral Gas ◽  
Self Gravity ◽  
Ultraviolet Observations ◽  
Diffuse Clouds ◽  
Intercloud Medium

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 ∼ 100 K), they are composed mostly of atomic species except for hydrogen which can be appreciably molecular, and they are dynamically controlled by their interaction with the intercloud medium. Dark clouds are relatively cold (T ∼ 10 K), they contain a rich variety of molecules, and self-gravity is important in their evolution. Because the interstellar extinction is a rapid function of wavelength, most ultraviolet observations have been of diffuse clouds. The IUE satellite is sufficiently powerful that observations of some dark clouds are possible, and an important area of future research will be to delineate more quantitatively the similarities and differences between diffuse clouds and dark clouds.With ultraviolet observations, considerable progress has been made in understanding the physical characteristics of clouds including determinations of their densities, temperatures, chemical compositions and dynamics (cf. Spitzer and Jenkins 1976). Because particular progress has been made on understanding the abundances within diffuse clouds and because of the limitations of space, we restrict this review to a discussion of abundances within diffuse clouds. These abundance measurements provide a set of fundamental astrophysical data.

scholarly journals The Mass Spectrum of Interstellar Clouds

1989 ◽  
Vol 120 ◽  
pp. 511-517
Author(s):  
John M. Dickey ◽  
R. W. Garwood
Keyword(s):  
Cross Sections ◽  
Molecular Clouds ◽  
Column Density ◽  
Unit Volume ◽  
Empirical Relationship ◽  
Line Of Sight ◽  
Interstellar Clouds ◽  
Absorption Studies ◽  
Low Latitudes ◽  
Diffuse Clouds

AbstractThe abundance of 21-cm absorption lines seen in surveys at high latitudes can be translated into a line of sight abundance of clouds vs. column density using an empirical relationship between temperature and optical depth. As VLA surveys of 21-cm absorption at low latitudes are now becoming available, it is possible to study the variation of this function with galactic radius. It is interesting to compare the abundance of these diffuse atomic clouds (with temperatures of 50 to 100 K and masses of 1 to 10 M⊙) to the abundance of molecular clouds. To do the latter we must make assumptions about cloud cross-sections in order to convert the line of sight abundance of diffuse clouds into a number per unit volume, and to convert from cloud column density to mass. The spectrum of diffuse clouds matches fairly well the spectrum of molecular clouds, although observationally there is a gap of several orders of magnitude in cloud mass. Optical absorption studies also agree well with the 21-cm results for clouds of column density a few times 1020 M⊙.

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