Formation of solar nebula and mass distribution in the planetary system

1976 ◽  
Vol 39 (2) ◽  
pp. 387-396 ◽  
Author(s):  
Ved Mitra
Keyword(s):  
Mass Distribution ◽  
Solar Nebula ◽  
Planetary System

scholarly journals Heliocentric Zoning of the Asteroid Belt by Aluminum-26 Heating

Science ◽  
1993 ◽  
Vol 259 (5095) ◽  
pp. 653-655 ◽  
Author(s):  
Robert E. Grimm ◽  
Harry Y. McSween
Keyword(s):  
Thermal History ◽  
Solar Nebula ◽  
Planetary System ◽  
Asteroid Belt ◽  
The Sun ◽  
Initial Concentration ◽  
Decay Products ◽  
Spectral Class ◽  
Time Required ◽  
Electrical Induction

The dependence of asteroid spectral class (and inferred composition and thermal history) on heliocentric radius has been held to be the result of heating by a solar energy source, most likely electrical induction, during the formation of the planetary system. Such variations in thermal history can be more simply explained by the presence of different amounts of the radionuclide aluminum-26, whose decay products are observed in meteorites, in planetesimals. These differences occurred naturally as a function of the increasing amount of time required to aecrete objects farther from the sun, during which aluminum-26 decayed from its initial concentration in the solar nebula. Both theory and isotopic evidence suggest that increases in aecretion time across the asteroid belt are of order several half-lives of aluminum-26, which is sufficient to produce the inferred differences in thermal history.

scholarly journals Session I: Origin of the Solar Nebula

1971 ◽  
Vol 2 ◽  
pp. 195-203 ◽  
Author(s):  
F. Hoyle
Keyword(s):  
Angular Momentum ◽  
Solar Nebula ◽  
Planetary System ◽  
The Other ◽  
Chemical Compositions ◽  
The Sun ◽  
Second Line ◽  
Mass Fractions ◽  
The One ◽  
Solar Material

Prof. Fred L. Whipple kindly agreed to be the chairman for all three panels, and introduced the next speaker, Prof. F. Hoyle, who spoke on ‘The Solar Nebula’. Hoyle: I would like to begin this contribution by considering the deductions we can make by comparing the gross chemical compositions of the planets with the composition of the Sun. For this purpose I have divided the planets into the three groups shown inThe second line gives the mass fractions in the Sun of the major constituents of the planetary groups, while the fourth line gives the factors by which the present masses must be multiplied to give the amounts of solar material needed to yield the appropriate amounts of main planetary constituents. The interesting points emerge that Jupiter and Saturn require the least amount of solar material, and that Uranus and Neptune on the one hand and the terrestrial planets on the other require approximately equal amounts. The total requirement is for ≈10-2Mʘ This is less by a factor ≈10 than the amount postulated in many theories of the origin of the planetary system. However the amount we have now calculated can readily be seen to be consistent with angular momentum requirements.

The Infancy of Solar-Type Stars and its Relevance for the Origin of Life

1997 ◽  
Vol 161 ◽  
pp. 267-282 ◽  
Author(s):  
Thierry Montmerle
Keyword(s):  
Main Sequence ◽  
Solar Nebula ◽  
Circumstellar Disks ◽  
T Tauri Stars ◽  
Necessary Condition ◽  
Sequence Evolution ◽  
T Tauri ◽  
Solar Type ◽  
Optical Domain ◽  
The Origin Of Life

AbstractFor life to develop, planets are a necessary condition. Likewise, for planets to form, stars must be surrounded by circumstellar disks, at least some time during their pre-main sequence evolution. Much progress has been made recently in the study of young solar-like stars. In the optical domain, these stars are known as «T Tauri stars». A significant number show IR excess, and other phenomena indirectly suggesting the presence of circumstellar disks. The current wisdom is that there is an evolutionary sequence from protostars to T Tauri stars. This sequence is characterized by the initial presence of disks, with lifetimes ~ 1-10 Myr after the intial collapse of a dense envelope having given birth to a star. While they are present, about 30% of the disks have masses larger than the minimum solar nebula. Their disappearance may correspond to the growth of dust grains, followed by planetesimal and planet formation, but this is not yet demonstrated.

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Mass distribution and Dynamical State of Galaxy Clusters in the LZLS Sample

2006 ◽  
Vol 20 ◽  
pp. 269-270 ◽  
Author(s):  
L.E. Campusano ◽  
E.S. Cypriano ◽  
L. Jr. Sodré ◽  
J.-P. Kneib
Keyword(s):  
Galaxy Clusters ◽  
Mass Distribution ◽  
Dynamical State

Mass distribution of hydrodynamic jets produced on the national ignition facility

2006 ◽  
Vol 133 ◽  
pp. 107-110 ◽  
Author(s):  
B. E. Blue ◽  
S. V. Weber ◽  
D. T. Woods ◽  
M. J. Bono ◽  
S. N. Dixit ◽  
...  
Keyword(s):  
Mass Distribution ◽  
National Ignition Facility
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