Galaxy 1 300 Miy 150 Mly Galaxy 2 Galaxy 3 Galaxy 4 MW Galaxy 5 450 Mly 190 Mly v,--4500 kmis v,--2200 kmis v, - 2830 km/s v, - 6700 km/s Figure 3.64 Five galaxies on a straight line, showing their distances and
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.
Use the distance and velocity data to
find the rate of expansion as a function of distance.
(b) If you extrapolate back in time, how long ago would all of
the galaxies have been at approximately the same position?
The two parts of this problem give you some idea of how the
Hubble constant for universal expansion and the time back to
the Big Bang are determined, respectively
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