The Birth and Death of Stars
Stars have existed in our universe for billions of years but have you ever wondered how they came to be? All stars have a birth and a death and follow a predicted life cycle however this cycle depends on the amount of matter gathered by the star at the time of its birth. The way that the birth and death of a star occurs also varies depending on its size and matter. There are three major categories that stars are divided into. 1. Those larger than 3-5 solar masses. 2. Those approximately our solar mass. 3. Those less than our sun.
NEBULAE - It is theorized that stars arise as a huge cloud of dust and hydrogen called Nebulae (Star Nurseries). The term 'Nebula' means cloud in Latin and this where the name originated from. They are in fact among the largest objects in the galaxy and can be up to hundreds of lights-years across. The process that occurs in these nebulae begins after an 'event' takes place so that the matter starts to move. An example of an event that would cause this is a supernova but it really could be anything that causes major movement out in the cosmos. Once this disturbance resonates through the nebula particles begin to slowly gather over millions of years.The matter gathers and compresses until large discs are formed. Pressure and heat eventually cause the atoms to fuse together and this will result in the formation of a protostar.
PROTOSTAR -
This is the stage in the stars life cycle where it undergoes gravitational collapse and nuclear fusion. Gravity wants to crush the star and these two forces fight against each other until they balance out during the main sequence. When the protostar reaches 10 million degrees it will create nuclear energy which will provide about 90% of the energy needed during the star's lifetime. As this energy is formed pressure begins to build up in the now very hot protostar. This heat causes nuclear fusion to occur and hydrogen is turned into helium. This helium is what produces the stars light. This is where the protostar begins to transform into a main sequence star. Protostars generally take around 100 000 years to reach the main sequence.
This is the stage in the stars life cycle where it undergoes gravitational collapse and nuclear fusion. Gravity wants to crush the star and these two forces fight against each other until they balance out during the main sequence. When the protostar reaches 10 million degrees it will create nuclear energy which will provide about 90% of the energy needed during the star's lifetime. As this energy is formed pressure begins to build up in the now very hot protostar. This heat causes nuclear fusion to occur and hydrogen is turned into helium. This helium is what produces the stars light. This is where the protostar begins to transform into a main sequence star. Protostars generally take around 100 000 years to reach the main sequence.
MAIN SEQUENCE -
This is the point where star has been born and starts to emit liquid and heat. Due to the now balanced forces of gravity and fusion the size of the star will now remain constant until it nears its death. Our sun is an example of a main sequence star. From this point on in the life cycle of a star they are split into three categories depending on their size. Their size will also determine how they die.
This is the point where star has been born and starts to emit liquid and heat. Due to the now balanced forces of gravity and fusion the size of the star will now remain constant until it nears its death. Our sun is an example of a main sequence star. From this point on in the life cycle of a star they are split into three categories depending on their size. Their size will also determine how they die.
The Difference Between Massive Stars and Small Stars:
There are many things that differentiate between small stars and massive stars. For one they both have very different life cycles especially concerning their deaths. The life cycle of a massive star is different because instead of becoming a red giant like a small star is fuses into a red super giant. From there the life cycle of the two types of stars is completely different. With a massive star it explodes into a supernova before becoming either a black hole or neutron star. Whereas a small star becomes a planetary nebula after the red giant phase, then finally it becomes a white dwarf then brown dwarf.
Obviously as the names suggest the size of these stars are also vastly different. A massive star is 3-5 solar masses whereas a small star is less than a solar mass.
Obviously as the names suggest the size of these stars are also vastly different. A massive star is 3-5 solar masses whereas a small star is less than a solar mass.
HR Diagram:
To the left is a HR Diagram that displays the temperature and absolute magnitude of stars. The diagram is also colour coded to display temperature. The ones in the dark blue section are the hottest and they slowly get cooler whilst moving down through the colours. The stars in red are the coolest.
BLUE - Highest temperature stars
RED - Coolest temperature stars
BLUE - Highest temperature stars
RED - Coolest temperature stars