Star Life And Death
Just like living organisms, stars have a life cycle. In the same way that you are born, develop, age and die, stars do the same things. One big difference is that stars don't need parents. Stars are born from huge clouds of gas and dust. It's amazing how that gas and dust are probably the most boring things in the universe and they can become everything, asteroids, planets and even stars. So you've got that huge cloud of dust and gas. Astronomers call that cloud a nebula. That's when it all starts to happen.
Contraction
That nebula starts to condense. Slowly but surely over millions of years, gas particles start to cling to each other, then they attract other particles and molecules. The nebula begins to condense and form a ball. That ball is called a protostar. "Proto" is a prefix that means "early" or "before." So a protostar is the first step in becoming a full-fledged burning star.
Start The Fire
After the star finished the protostar phase, it becomes even denser. The heavy elements move to the center of the star while the light gases stay in the star's atmosphere. Those gases are usually hydrogen (H) and helium (He). Then something amazing happens, the nuclear fire begins. The star heats up and the gases ignite. This step in the development process is called the main sequence. If you looked, you would see the birth of the star.
Not All Of Them Make It
In the Solar System section we speak a little about Jupiter. Jupiter is a special planet in that it has a very similar makeup to the Sun. It has a low density and hydrogen and helium are the main components of the atmosphere. It is still missing one thing, nuclear fire. Jupiter could be the star that never was.
Reaching Middle Age
After the main sequence, stars become what astronomers call red giants. This is the time when the star begins to die. As with anything in nature, stars need fuel. Well there is only so much hydrogen to fuel a star's fusion reactions. Eventually that fuel runs out. When the star begins to cool, it grows. The cooling takes the color of the star and drops it into the red range, leaving a red giant. A nearby star named Betelgeuse is a red giant.
Losing Its Atmosphere
So the star is cooling and the fire is burning out. If the star has a really large mass, there comes a point where the star's reactions stop and an explosion occurs. One day, BOOM! That boom is the supernova. After that explosion, the atmosphere is blown away from the star. In the same way there was a nebula of gas and dust before the star was born, a new nebula is created from the explosion. Astronomers call the nebula after the explosion a planetary nebula.
Sometimes It's Not The End
Sometimes the star continues to contract and its gravity increases. Imagine that the Earth contracted. First to half its size and then a quarter. Then even smaller. Imagine that the entire mass of the Earth was able to fit in your house. The gravity would be enormous. That's what happens with some stars. They continue to contract and their gravity increases. They become black holes. Black holes have gravity so strong that even light cannot escape the star.
Name______Life Cycle of a Star Questions
1)A star starts in a cloud of gas and dust called a
a)galaxyb) nebulac) asteroidd) protostar
2)The gravity pulls the gas and dust together into a ball called a
a)galaxyb) nebulac) asteroidd) protostar
3)The star ignites when
a)Two helium atoms form a hydrogen atom
b)Hydrogen runs out completely
c)two hydrogen atoms form a helium atom
d)gravity creates heat and eventually light
4)The act of igniting is caused by
a)Radiationc) ultraviolet waves
b)Gravitational pulld) nuclear fusion
5)Once the star has ignited, the star’s stage is called
a)main sequencec) new protostar
b)red giantd) planetary nebula
6)The beginning stage of a star’s death is called
a)main sequencec) black hole
b)red giantd) white dwarf
7)When the hydrogen runs out, the star gets
a)smaller and hotterc) smaller and cooler
b)bigger and coolerd) bigger and hotter
8)After a star is burnt out, it can become a
a)main sequencec) black hole
b)red giantd) white dwarf
Use the above diagram to answer the following questions.
Write GMS for greater mass star and LMS for lesser mass star or BOTH.
______9) Explodes as a supernova
______10) Becames a white and then black dwarf
______11) Starts in a nebula
______12) Becomes a super giant.
______13) Contracts to form a protostar.
______14) its heat and light is caused by nuclear reactions
______15) Can end as a neutron star or blackhole.