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Transcript of Chapter 13.4
Science 9 Peer Teaching Project By
Jonah Thornburn, What is This Chapter About?
By the name of it, you may have guessed stars...
And you were right!
The life of a star is complex, and lasts billions
of years, until it will face it's last stages of life.
From fading out of existence, to exploding, it'll
all be covered in our presentation...
Let us begin! Hertzsprung-Russel Diagram Shows many characteristics of a star, such as its luminosity, temperature, and its life. The luminosity is the energy output, and for reference, the sun is labeled 'one'. Most stars fit here. The solar mass determines where it will sit. Cool, dim stars will go on the lower right side Massive, bright, hot stars go in the upper left Finally, the white dwarfs are on the lower left. w h i t e
d w a r f s b l u e g i a n t s r e d d w a r f s Once all of the hydrogen of a star is used, its energy production will change,
and will be moved to the upper right hand side, as a supergiant. s u p e r g i a n t s The sun, which is also a star, contains hydrogen that will be converted to helium after 10 billion years, and will change it drastically, into a Red Giant. Now, the sun (red giant) will become a white dwarf, which is a star with no more than 1.4 solar masses As it is forming a white dwarf, it will release particles that will run into the the matter it lost in the last stages of being a red giant. The collision of all the matter and particles will then form a nebula, as you can see in the background. The white dwarf will now remain in the galaxy, and will act as the sun through radiating energy. This is a video to explain what happens next. White dwarfs eventually run out of light, becoming a black dwarf, which will be completely invisible. This is a star-forming body. Supernovas A dying star that releases energy and matter The energy and matter released forms another nebula The mass of the star will determine whether the supernova will produce
a neutron star, or a black hole. 10-50 solar masses over 50 solar masses The star will begin to contract, and will undergo carbon fusion Carbon fusion is a complicated process that produces iron and nickel These elements will not undergo more fusion at these temperatures and pressures, which are currently collapsing the star continuously The energy that has been produced can now drive the formation of elements that are heavier than iron (Copper, nickel, etc.) Although, the inward collapsing matter within the star bounces off of the core milliseconds later This occurs through a shock wave, which also blows away any remaining materials A shock wave is a large wave of matter, and energy. These elements will eventually form a new world It relocates all the elements throughout space Until then, the star will shine for a few more months before it dies. Questions The person who answers the most amount of questions right will not have to do the crossword. Second, third and fourth will receive a candy. And finally, the fifth person shall get a pat on the back. 1. Where do cooler stars go on the H-R diagram? And please, for fairness, do not look at your notes! (H-R) In the lower right portion (red dwarfs) 2. What is the definition of luminosity? Luminosity is the energy output of a star 3. What happens to a star after all of its hydrogen is used up? It will become a supergiant through the changing of energy output The sun shrinks, due to the flow of energy caused by loss of hydrogen Then, helium fusion begins, which will produce elements that are less heavy than carbon and oxygen Some facts missed in the video Now, the sun has finished forming, and is now a red giant The red giant (according to the textbook) is now several times it's original brightness. Questions 1. What produces elements that are less heavy than oxygen and carbon? Helium fusion 2. What part of the sun will begin to contract? The core of the sun 3. What element within the sun will be converted into helium? Hydrogen Questions 1. What will the particles released while forming a white dwarf run in to? Matter that was lost when forming a red giant 2. What will happen when the white dwarf runs out of energy? It will become a black dwarf 3. When all of the particles collide, what do they form? They form a nebula Questions What is a shockwave? A wave of matter and energy As the star contracts, what is also occurring? Carbon fusion Neutron Stars As stated earlier, Supernovas form neutron stars if the stars mass is between 10 and 50 solar masses Wilson Yuan,
Joey Leung, and Alistair Yee The core is made of neutrons The neutrons are very tightly packed This causes it to have an extremely large mass Pulsars are a type of neutron star Sends out light accomponied by a beam that contains high-energy radio waves The pulsar rotates at the same time, and looks as if it was a lighthouse Although, if the neutron star has less
than two solar masses, it will eventually run out of energy and fade away. . . Questions 1. What does a pulsar look like? A pulsar looks like a lighthouse 2. What occurs while the pulsar gives off the beam of energy? The pulsar rotates 3. If a neutron star fades away, how many solar masses would it have had? Less than two solar masses Black Holes As stated earlier, supernovas produce black holes if the stars mass was over 50 solar masses As stated earlier as well, a shock wave blows materials of a star away. Materials blown away with masses above four solar masses will cause the core to collapse within itself This collapsed object still keeps it mass, but is much smaller. Since it is smaller yet still has the same mass, the gravitational pull will be amplified greatly The gravitational pull is so large that nothing can avoid it, and will be pulled into it. Not even light itself can escape it As an example, a black hole with 10 solar masses would be 60 km in diameter. This may sound huge, but black holes are extremely far away, and give off no light. It's like trying to find a needle in a haystack that's on the moon, but by looking from earth. The first black hole was discovered by looking at both at a binary star consisting of a blue giant orbiting the black hole. A binary star is two stars circling each other The black hole pulled gas from the blue giant The gas then began to heat up The gas then emitted X-rays, which scientists were able to detect, and lead them to infer where the black hole would be. The blue giant had a solar mass of 27 The black hole (now Cygnus X-1) had a solar mass of 14 The Big Picture A star goes through billions of years of using hydrogen Once it is all used up it either fades away or explodes Hertzprung-Russel diagrams can be used to display the life of a star All stars are compared to the sun For reference, the sun has one solar mass, and one luminosity After 10 billion years, almost all of the suns hydrogen will be helium Without hydrogen, the core will contract and outer layers expand The sun, now a red giant, will engulf all nearby planets A white dwarf is a star with no more than 1.4 solar masses The sun, being 1 solar mass, will become a white dwarf The white dwarf will shed matter that will collide with other matter,
creating a nebula The white dwarf will shine until it runs out of energy, becoming a black dwarf. Stars with over 10 solar masses cause a supernova This is a shock wave that is caused by carbon fusion causing the explosion of elements throughout space Neutron stars are created by stars that had 10-50 solar masses Extremely dense core made of neutrons Pulsars are neutron stars that send out a beam of energy while rotating Black holes are formed by stars that had over 50 solar masses Matter left behind by supernovas greater than 4 solar masses will have its core collapse within itself Due to the mass staying the same, the gravitational pull will be unavoidably strong Since not even light can escape it, it will give off no light and will be undetectable The first black hole, Cygnus X-1, discovered by studying X-ray emissions caused by heating of gas received off of a blue giant Your homework is : 1. Finish notes if you missed some of the Prezi (will be checked) 2. Finish the crossword, will be marked in class 3. Finish the worksheets provided (fill in the blank and questions, will be marked in class) Thank you for bearing through our presentation! We hope it was a learning experience! Questions 1. What is the name of the first black hole discovered? Cygnus X-1 2. If the mass of the materials blown away is above _____ , the core will collapse within itself. Four 3. Are black holes stars? No, black holes are not stars. These elements then expand the outer layers of the sun Absolute magnitude is how much light is given off by the star.