Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
6.133 Blackbody
dependence of the radiation energy emitted by an object
on wavelength at a certain temperature. Planck proposed the quantum theory to account for the dependence.
Shown in the figure is a plot of the radiation energy
emitted by our sun versus wavelength. This curve is
characteristic of objects at about 6000 K, which is the
temperature at the surface of the sun. At a higher
temperature, the curve has a similar shape but the
maximum will shift to a shorter wavelength. (a) What
does this curve reveal about two consequences of
great biological significance on Earth? (b) How are
astronomers able to determine the temperature at the
surface of stars in general?
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