Some Salient Features of Evolving Models of Interstellar Clouds

1989 ◽  
pp. 345-355 ◽  
Author(s):  
S. P. Tarafdar ◽  
S. K. Ghosh ◽  
K. R. Heere ◽  
S. S. Prasad
Keyword(s):  
Interstellar Clouds ◽  
Salient Features ◽  
Evolving Models

scholarly journals Some Salient Features of Evolving Models of Interstellar Clouds

1989 ◽  
Vol 8 ◽  
pp. 345-355
Author(s):  
S. P. Tarafdar ◽  
S. K. Ghosh ◽  
K. R. Heere ◽  
S. S. Prasad
Keyword(s):  
Chemical Evolution ◽  
Critical Mass ◽  
Initial Density ◽  
Evolutionary Model ◽  
Interstellar Clouds ◽  
Density Relation ◽  
Physical And Chemical ◽  
Collapsing Cloud ◽  
Evolving Models ◽  
Bounce Back

ABSTRACTDifficulties faced by various models of interstellar clouds have been discussed. A new evolutionary model which uses energy equation instead of empirical temperature-density relation used in earlier models has been presented. This calculation shows that for a given initial density, the collapsing cloud has a minimum mass which is significantly smaller than the Jean's mass. The clouds with larger mass than the critical mass continue collapsing and physical and chemical evolution remain similar to earlier evolving models. Clouds with mass smaller than the critical mass initially collapse but ultimately bounce back, producing physically similar clouds in collapsing and expanding phases. The chemical evolution in these two physically similar clouds is different mainly due to differences in their lifetime. The lifetime of this oscillating cloud is also longer than the collapsing cloud.

Dynamics of comets in the collapsing protosolar nebula

1999 ◽  
Vol 173 ◽  
pp. 45-50
Author(s):  
L. Neslušan
Keyword(s):  
Solar System ◽  
Velocity Distribution ◽  
Oort Cloud ◽  
Interstellar Clouds ◽  
Protosolar Nebula ◽  
Moving Bodies

AbstractComets are created in the cool, dense regions of interstellar clouds. These macroscopic bodies take place in the collapse of protostar cloud as mechanically moving bodies in contrast to the gas and miscroscopic dust holding the laws of hydrodynamics. In the presented contribution, there is given an evidence concerning the Solar system comets: if the velocity distribution of comets before the collapse was similar to that in the Oort cloud at the present, then the comets remained at large cloud-centric distances. Hence, the comets in the solar Oort cloud represent a relict of the nebular stage of the Solar system.

Evolving models of how housing can support recovery

2003 ◽  
Author(s):  
K. Scrimenti ◽  
B. Kloos
Keyword(s):  
Support Recovery ◽  
Evolving Models

Modelling polarized radiation from interstellar clouds

2008 ◽  
Vol 31 ◽  
pp. 179-180
Author(s):  
M. Juvela ◽  
J. Goncalves ◽  
V.-M. Pelkonen ◽  
T. Lunttila
Keyword(s):  
Interstellar Clouds ◽  
Polarized Radiation

Metastable Defects in the Amorphous Silicon-Germanium Alloys

2003 ◽  
Vol 762 ◽  
Author(s):  
J. David Cohen
Keyword(s):  
Amorphous Silicon ◽  
Silicon Germanium ◽  
Dangling Bonds ◽  
Annealing Behavior ◽  
Fundamental Properties ◽  
Silicon Materials ◽  
Salient Features ◽  
The Individual ◽  
Amorphous Silicon Germanium ◽  
Silicon Germanium Alloys

AbstractThis paper first briefly reviews a few of the early studies that established some of the salient features of light-induced degradation in a-Si,Ge:H. In particular, I discuss the fact that both Si and Ge metastable dangling bonds are involved. I then review some of the recent studies carried out by members of my laboratory concerning the details of degradation in the low Ge fraction alloys utilizing the modulated photocurrent method to monitor the individual changes in the Si and Ge deep defects. By relating the metastable creation and annealing behavior of these two types of defects, new insights into the fundamental properties of metastable defects have been obtained for amorphous silicon materials in general. I will conclude with a brief discussion of the microscopic mechanisms that may be responsible.

Preliminary Observations of Interstellar Sodium D-Line Absorption towards the Carina Nebula

1980 ◽  
Vol 4 (1) ◽  
pp. 95-97 ◽  
Author(s):  
J. B. Whiteoak ◽  
F. F. Gardner
Keyword(s):  
High Resolution ◽  
Hii Regions ◽  
Early Type ◽  
Interstellar Clouds ◽  
Carina Nebula ◽  
Line Absorption ◽  
General Investigation ◽  
Early Type Stars ◽  
Resolution Study

As part of a general investigation of interstellar clouds associated with southern HII regions we have begun a high-resolution study of the sodium D-line absorption in the directions of early-type stars that are likely to be associated with or located behind the clouds.

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