The Life Cycle of Stars PDF

 Review Say Fact if the statement is correct and Bluff if it is wrong. 1. Sun is the main source of energy on Earth. 2. Sun is the nearest stars on Earth. 3. Moon is also considered as star that emits its own light. 4. The rotation of the Earth on its axis...

 Review Say Fact if the statement is correct and Bluff if it is wrong. 1. Sun is the main source of energy on Earth. 2. Sun is the nearest stars on Earth. 3. Moon is also considered as star that emits its own light. 4. The rotation of the Earth on its axis cause the change of the season. 5. Stars are members of the Solar system.  What is star? ❖ a huge glowing ball of hot gas, mainly hydrogen and helium ❖ When stars are grouped together we call them “constellations” ❖ A ball of plasma held together by its own gravity  Where stars are born? The “ EAGLE” nebula Nebula Is a giant gas of dust and gas in space Nursery for stars Also come from a gas and dust that comes from the explosion of a dying star Some most common nebulae  How stars are born? Stars are formed from a giant clouds of dust and gas. The gravity , the cloud collapses into a rotating gaseous ball Once the new star gets hot it will begin to create a energy from a process called NUCLEAR FUSSION Characteristics Characteristics of of Stars Stars  Temperature and color Cooler stars tends to be a red or orange stars Hotter stars tends to be a white or blue stars Stars in mid ranges tends to be yellow Distance - The stars distance are measured in Light-Year - Light-year is equivalent to the distance that light travels in one year which is 9.46 x 1012 km or nearly 6 trillion kilometers.  Brightness 2 characteristics 1.Luminosity-Amount of light that a stars radiates 2.Magnitude-A stars is its perceived brigthness Brightness Measures of stars true brightness is called magnitude or absolute magnitude. Absolute magnitude – is the magnitude of star if it were located at a certain standard distance. Apparent magnitude – the brightness of stars as seen on Earth.  Size https://www.youtube.com/watch?v=GoW8Tf7hTGA Dwarf stars -Small stars,20 times larger than our sun and 20,000 times brighter -a star of relatively small size and low luminosity. Most main sequence stars are dwarf stars. Red dwarf stars -are by far the most common type of star in the Milky Way -These stars usually is low luminosity  OLD LARGE STARS Blue giants -A huge,very hot blue star. Its a main sequence star that usually burns a HELIUM Super Giants -The largest know type of stars. Betelgeusse and Rigel are supergiants are the example of super giants.  Mass Stellar mass is the most important property of stars but also the most difficult to measure. Kepler’s Las of Planetary motion is use to measure stellar mass. Binary systems the orbital period and the separation if two stars arer measured. The sum of the masses of two stars are equal to the cube of their mean distance by the square of the revolution of the stars. 𝑟3 m1+ m2 = 2 𝑇  The Sun The sun is a yellow dwarf medium sized stars All stars will die and soon our sun will die in approximately 5 billions years form now(as of NASA).Once the supply of hydrogen is exhausted. Our star expands to become a red giant and then tears its body to pieces to condense into a white dwarf Why does a star TWINKLE? The twinkling of stars (stellar scintillation/astronomical scintillation)is caused by the REFRACTION OF LIGHT passed through the atmosphere in earth As their light travels through the mant layers of the earth’s atmosphere,the light of the star is bent many times and in random direction This random refraction result in the star winking (it looks as through the stars moves a bit and our eyes interprets like the stars is twinkling Stars(except for the sun) appear as tiny dots in the sky The death of stars?? The stars will die if they will runs out of gases to burn The star will expand into a super giant 1. Planetary Nebula 1. Black hole 2. Gamma Ray Burst A star after it explodes The “CRAB” nebula