Shiv S Kumar Biography
Shiv S Kumar Biography
 

BACKGROUND

Dr. Shiv S. Kumar was born on March 15, 1939 in Bannu, India (now Pakistan) and earned his Ph.D. degree in Astronomy from the University of Michigan on February 3, 1962. Dr. Kumar has been working on the problems of the origin and evolution of low-mass stars, the origin of the Solar System, the theory of stellar atmospheres, the existence and characteristics of planets beyond the Solar System, the origin and evolution of life in the universe, and other problems since 1957.

During the period 1958-1962, he developed the theory of the very-low-mass gaseous objects that are unable to sustain hydrogen-burning thermonuclear reactions. This theory led to the prediction (in 1962) of the possible existence in the universe of the astronomical objects currently called brown dwarfs. The main results of the then-new theory were presented by Dr. Kumar at a meeting of the American Astronomical Society held at Yale University in August 1962. The abstract of this paper was published in the Astronomical Journal in November 1962 and it can be accessed online:

STUDY OF DEGENERACY IN VERY LIGHT STARS
http://adsbit.harvard.edu/cgi-bin/nph-iarticle_query?bibcode=1962AJ.....67S.579K

Details of his theory were submitted to the Astrophysical Journal in October 1962 in the form of two papers. These papers were accepted for publication in November 1962 by the Astrophysical Journal. You may access the papers online:

THE STRUCTURE OF STARS OF VERY LOW MASS
 
Shiv S. Kumar
NASA Goddard Space Flight Center
Institute for Space Studies
New York 27, N.Y.
Received October 20, 1962; revised November 27, 1962
 
ABSTRACT

Completely convective models have been constructed for stars of masses 0.09, 0.08, 0.07, 0.06, 0.05, and 0.04 (solar units), taking into account the non-relativistic degeneracy of the stellar material. It is shown that there is a lower limit to the mass of a main-sequence star. The stars with mass less than this limit become completely degenerate stars or "black" dwarfs as a consequence of gravitational contraction, and, therefore, they never go through the normal stellar evolution.

(click here for full article)

THE HELMHOLTZ-KELVIN TIME SCALE FOR STARS OF VERY LOW MASS
 
Shiv S. Kumar
NASA Goddard Space Flight Center
Institute for Space Studies
New York 27, N.Y.
Received October 20, 1962; revised November 21, 1962
 
ABSTRACT

Assuming that the contracting stars in convective equilibrium evolve vertically downward in the H-R diagram, a simple expression for the Helmholtz-Kelvin time scale tHK is derived. Application of this expression to stars of mass M < 0.1M shows that these stars contract to a radius of about 0.1R in a time scale of approximately 1 billion years, while the earlier estimates, based on horizontal evolution, gave a time scale tHK greater than a hundred billion years.

(click here for full article)

After a very long search lasting over a period of 33 years, the existence of brown dwarfs (also known as Kumar objects/black dwarfs) was observationally confirmed in 1995. Recent observational work clearly demonstrates that the Milky Way Galaxy contains a very large population (billions and billions!) of the luminous and dark very-low-mass objects as predicted back in 1962. The story behind the theoretical discovery of brown dwarfs (Kumar objects) during the period 1958-1962 may be found by clicking here. This paper was published in June 2003 in the Proceedings of the International Astronomical Union Symposium #211 held at Waikoloa, Hawaii (May 2002).

A short biography of Dr. Kumar is available here. (pdf)

Shiv S Kumar Biography


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