Supernovae and interstellar gas dynamics

1967 ◽  
Vol 31 ◽  
pp. 117-119
Author(s):  
F. D. Kahn ◽  
L. Woltjer
Keyword(s):  
Lower Limit ◽  
High Velocity ◽  
Gas Dynamics ◽  
Interstellar Cloud ◽  
Interstellar Gas ◽  
Random Motions ◽  
Relativistic Particles

The efficiency of the transfer of energy from supernovae into interstellar cloud motions is investigated. A lower limit of about 0·002 is obtained, but values near 0·01 are more likely. Taking all uncertainties in the theory and observations into account, the energy per supernova, in the form of relativistic particles or high-velocity matter, needed to maintain the random motions in the interstellar gas is estimated as 1051·4±1ergs.

scholarly journals High-velocity interstellar absorption associated with the supernova remnant W28

2020 ◽  
Vol 495 (3) ◽  
pp. 2909-2920 ◽  
Author(s):  
Adam M Ritchey
Keyword(s):  
High Velocity ◽  
Molecular Cloud ◽  
Supernova Remnant ◽  
Line Emission ◽  
Line Of Sight ◽  
Interstellar Gas ◽  
Lower Velocity ◽  
North East ◽  
The North ◽  
Visible Wavelengths

ABSTRACT We present an analysis of moderately high-resolution optical spectra obtained for the sightline to CD−23 13777, an O9 supergiant that probes high-velocity interstellar gas associated with the supernova remnant W28. Absorption components at both high positive and high negative velocity are seen in the interstellar Na i D and Ca ii H and K lines towards CD−23 13777. The high-velocity components exhibit low Na i/Ca ii ratios, suggesting efficient grain destruction by shock sputtering. High column densities of CH+, and high CH+/CH ratios, for the components seen at lower velocity may be indicative of enhanced turbulence in the clouds interacting with W28. The highest positive and negative velocities of the components seen in Na i and Ca ii absorption towards CD−23 13777 imply that the velocity of the blast wave associated with W28 is at least 150 km s−1, a value that is significantly higher than most previous estimates. The line of sight to CD−23 13777 passes very close to a well-known site of interaction between the supernova remnant and a molecular cloud to the north-east. The north-east molecular cloud exhibits broad molecular line emission, OH maser emission from numerous locations, and bright extended GeV and TeV γ-ray emission. The sightline to CD−23 13777 is thus a unique and valuable probe of the interaction between W28 and dense molecular gas in its environs. Future observations at ultraviolet and visible wavelengths will help to better constrain the abundances, kinematics, and physical conditions in the shocked and quiescent gas along this line of sight.

scholarly journals Some Characteristics of Interstellar Gas in the Galaxy

1970 ◽  
Vol 39 ◽  
pp. 22-50 ◽  
Author(s):  
Harold F. Weaver
Keyword(s):  
Gas Dynamics ◽  
Theoretical Models ◽  
Structural Features ◽  
Interstellar Gas ◽  
Great Breadth ◽  
The Galaxy ◽  
The Subject

The task assigned for this review is to discuss structural features of the Galaxy as they may involve or relate to gas dynamics. Since a topic of such great breadth would permit discussion of essentially any aspect of the Galaxy, we shall narrow the view and direct attention primarily towards the larger-scale features of the system. In particular, effort will be made to place emphasis on those areas of the subject in which problems of interpretation exist and in which new theoretical models are needed.

A Discussion on astronomy in the ultraviolet - Skylark rocket observations of ultraviolet spectra of γ 2 Velorum and ζ Puppis

1975 ◽  
Vol 279 (1289) ◽  
pp. 355-369 ◽  
Keyword(s):  
Wavelength Range ◽  
Spectral Resolution ◽  
High Velocity ◽  
Stellar Atmospheres ◽  
Photographic Film ◽  
Line Of Sight ◽  
Line Profiles ◽  
Interstellar Gas ◽  
Stellar Spectra ◽  
Ultraviolet Spectra

A star-stabilized Skylark rocket was launched from Woomera in June 1973 to record ultraviolet spectra of the bright stars y 2 Velorum and £ Puppis. The instrumentation consisted of three Wadsworth-mounted objective grating spectrographs with a combined wavelength range 90-230 nm. Stellar spectra were recorded on Kodak 101-01 photographic film, the in-flight spectral resolution being approximately 30 pm. Two exposures were obtained on each of the target stars. The y 2 Vel spectrum observations extend from 92 to 230 nm and the £ Pup spectrum from 100 to 230 nm. Analysis of the spectra provides information about the composition and properties of the interstellar gas in the line of sight. The observations also provide useful data on the stellar atmospheres. P Cygni line profiles are observed in the spectra of both stars indicating that high velocity material is being ejected.

Spiral magneto-electron waves in interstellar gas dynamics

2001 ◽  
Vol 93 (4) ◽  
pp. 671-676 ◽  
Author(s):  
S. I. Bastrukov ◽  
J. Yang ◽  
D. V. Podgainy
Keyword(s):  
Gas Dynamics ◽  
Interstellar Gas

scholarly journals Bar-Induced Shocks and the Nature of Regions of Violent Star Formation

1996 ◽  
Vol 157 ◽  
pp. 426-428
Author(s):  
A. D. Chernin
Keyword(s):  
Star Formation ◽  
Gas Dynamics ◽  
Large Scale ◽  
Interstellar Gas ◽  
Favorable Conditions ◽  
Shock Fronts

AbstractGas dynamics induced by bars involves large-scale shocks. The shock fronts may be curved, especially near the bar edges. Evolution of the curved shocks can lead to effective compression of the interstellar gas which produces favorable conditions for violent star formation in the vicinity of bars.

scholarly journals Kinematics of Extremely Faint Dwarf Galaxies

2004 ◽  
Vol 220 ◽  
pp. 347-352
Author(s):  
Ayesha Begum ◽  
Jayaram N. Chengalur
Keyword(s):  
Galaxy Formation ◽  
High Velocity ◽  
Hierarchical Models ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Velocity Fields ◽  
Velocity Gradients ◽  
Irregular Galaxies ◽  
Random Motions ◽  
Dwarf Irregular Galaxies

We present the results of deep, high velocity resolution (~1.6 km s−1) Giant Meterwave Radio Telescope (GMRT) HI 21 cm observations of extremely faint (Mb > −12.5) dwarf irregular galaxies. We find that all of our sample galaxies show systematic large scale velocity gradients, unlike earlier studies which found chaotic velocity fields for such faint galaxies. For some of the sample galaxies the velocity fields are completely consistent with ordered rotation, though the peak circular velocities are comparable to the observed random motions. These are the faintest known galaxies with such regular kinematics. We present (“asymmetric drift” corrected) rotation curves and mass models (including fits for Isothermal and NFW halos) for some of these galaxies and discuss the implications for hierarchical models of galaxy formation.

scholarly journals Simulations of Gas Clouds in Interacting Galaxies

1990 ◽  
Vol 124 ◽  
pp. 749-753
Author(s):  
Magnus Thomasson
Keyword(s):  
High Velocity ◽  
Stellar Population ◽  
Velocity Dispersion ◽  
Morphological Changes ◽  
Interacting Galaxies ◽  
Two Dimensional ◽  
Low Velocity ◽  
Planar Orbit ◽  
Random Motions ◽  
Companion Galaxy

A companion can induce a varitey of morphological changes in a galaxy. I use N-body simulations to study the effects of different kinds of perturbations on the dynamics of a disk galaxy. The model is two-dimensional, with a disk consisting of about 60,000 particles. Most of the particles (80 %) represent the old stellar population with a high velocity dispersion, while the rest (20 %) represent gas clouds with a low velocity dispersion. Initially, the velocity dispersion corresponds to Q = 1 for the “star” particles, and Q = 0 for the “gas” particles, where Q is Toomre’s (1964) stability parameter. The gas clouds can collide inelastically. The disk is stabilized by a rigid halo potential, and by the random motions of the old “star” particles. To simulate the effect of an encounter on the disk, a companion galaxy, modelled as a point mass, can move in a co-planar orbit around the disk. A complete description of the N-body code is found in Thomasson (1989).

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