CNO cycle

Dynamical time scale

At high temperatures corresponding to stars with mass above 1.5 times the solar masses that is the CNO cycle becomes dominant because its reaction rate increases more rapidly with temperature. In CNO cycle, C, O…

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The Proton Proton Chain

proton proton chain

This proton proton chain is most important energy source in stars with mass below 1.5 times the solar masses. At the center part of these stars, temperature is of the order of which is enough…

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Stellar Energy Sources

Dynamical time scale

In 1938, H. Bethe and F.V. Weizacker independently put forward the first detailed mechanism for energy production in the stars. They concluded that the temperature at the core of the star is enough for thermonuclear…

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Color Index and UVB Photometry

Dynamical time scale

The difference between photographic and visual magnitude is called color index (C.I.) of the star.   Photographic magnitudes can be measured with photographic plates sensitive to other region of the electromagnetic spectrum. This magnitude is called…

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The Sun

Hertzsprung-Russell diagram

The Sun is the Solar System’s parent star. Its large mass gives it an interior density high enough to sustain nuclear fusion, which releases enormous amounts of energy, mostly radiated into space as electromagnetic radiation…

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Stellar Magnitude

stellar magnitude

In 2nd century BC Hipparchus compiled a catalog of stars. Based on this catalog Ptolemy introduced a system of assigning Stellar Magnitude to each star “a number” depending on its brightness. Ptolemy suggested ‘1’ for…

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