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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Channels for Astronomical Information

stellar magnitude

Four entirely independent channels are known to exist by means of which information can reach us from distant part of the universe. 1. Electromagnetic radiation: gamma rays, x rays, ultraviolet, visible, infra-red and radio waves….

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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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The Solar System

Solar System

The Solar System consists of the Sun and those celestial objects bound to it by gravity. These objects are the eight planets, their 166 known moons, five dwarf planets, and billions of small bodies. The…

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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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