1. 2005 K.Corbett Life Cycle of Stars

2. 2005 K.Corbett 3 categories of stars  Sun-sized stars  (up to 6 times the size of the sun)  Huge stars  (6 - 30 times the size of the sun)  Giant Stars  (over 30 times the size of the sun)

3. 2005 K.Corbett The life of Sun-sized stars  Born in a nebula (a cloud of gas and dust, mostly Hydrogen).  The star produces energy from nuclear fusion of Hydrogen into Helium.  This type of star lasts for about 10 billion years.

4. 2005 K.Corbett The death of Sun-sized stars  Once their fuel is used up, the core shrinks and the outer layers begin to expand forming a red giant.  Eventually, the star loses enough mass that it becomes a white dwarf.  White dwarfs continue to lose heat and eventually become black dwarfs.

5. 2005 K.Corbett The life of Huge stars  Born in a huge nebula (a cloud of gas and dust, mostly Hydrogen).  The star produces energy from nuclear fusion of Hydrogen into Helium.  This type of star uses up its fuel faster than sun-sized stars.

6. 2005 K.Corbett The death of Huge stars  Once their fuel is used up, the core shrinks and the outer layers begin to expand forming a super red giant.  Eventually, the star’s core collapses so much that it explodes in a supernova.  This size star will eventually become a neutron star - a star that has about 1.5 times the mass of our sun, but only about 10 km in diameter.

7. 2005 K.Corbett The life of Giant stars  Born in a huge nebula (a cloud of gas and dust, mostly Hydrogen).  The star produces energy from nuclear fusion of Hydrogen into Helium.  This type of star uses up its fuel faster than sun-sized stars, only living a few million years.

8. 2005 K.Corbett The death of Giant stars  Once their fuel is used up, the core shrinks and the outer layers begin to expand forming a super red giant.  Eventually, the star’s core collapses so much that it explodes in a supernova.  This size star will collapse on itself so much that it’s gravity takes over completely and not even light can escape. It becomes a black hole.

9. 2005 K.Corbett 9 Old Age of Massive Stars  Supernova Remnants  The huge, glowing cloud of debris that expands from a supernova explosion sweeping up interstellar material as it goes is called a supernova remnant  Supernova remnants have a more ragged look compared to planetary and other nebulas  Two well-known supernova remnants  Crab Nebula – Visual outburst witnessed by astronomers in China in 1054 A.D.  Supernova 1987A – Most recent visual supernova and a rare blue supergiant explosion

10. 2005 K.Corbett

11. Properties of Stars  Astronomers classify stars by their color, size, and brightness. Other properties of stars are chemical composition and mass.  Color and Temperature – a stars color indicates the temperature of its’ surface.  The hottest stars appear blue  The cooler stars appear red  The spectrum of color in a star is from blues to greens to yellows and reds.

12. 2005 K.Corbett Brightness  The brightness of a star as viewed from Earth is dependent on many factors such as color intensity and distance.  Apparent Brightness/Magnitude – is the brightness of a star as it appears from Earth.  The apparent brightness decreases as its distance from you increases  Absolute Brightness/Magnitude – is how bright a star really is. The absolute brightness is a characteristic of the star and is not dependent on its distance from Earth.

13. 2005 K.Corbett Hertzsprung-Russell Diagram

14. 2005 K.Corbett Main Sequence Stars  A major grouping of stars that forms a narrow band from the upper left to the lower right when plotted according to luminosity and surface temperature on the Hertzsprung-Russell diagram

15. 2005 K.Corbett Types of Stars Classification ClassTemperatureColor O20,000- 60,000 KBlue B10,000 – 30,000 KBlue-white A7,500 – 10,000 KWhite F6,000 – 7,500 KYellow-white G5,000 – 6,000 KYellow K3,500 – 5,000 KOrange M2,000 – 3,500 KRed