Hw 8 Astro Sal

.docx

School

Georgia State University *

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Course

1020

Subject

Physics

Date

Dec 6, 2023

Type

docx

Pages

Uploaded by KidHummingbirdMaster698 on coursehero.com

ASTR 1020 Homework Assignment 8 Please note: If there is a pre-selected answer for any of the True/False or Multiple Choice questions below it will be the default of “a”. This does NOT automatically mean that “a” is the correct answer. It may or may not be correct. Type in your answers for the review questions below and adjust the selection of the multiple choice answers as you see fit. Then submit under Assessments/Assignments Homework dropbox. 1. Why is mass so important to a star's life? How and why do we divide stars into groups by mass? The birth mass determines the fusion progression within the core of the star, we divide these into groups because lower mass stars usually live longer than higher mass stars and they can produce different elements trough fusion. 2. When a star exhausts its core hydrogen fuel, the core contracts but the star as a whole expands. Why? The inner portions being more dense and closer to the gravitational center fall at a faster rate. Before the outer portions have a chance to fall in too far, the core starts new fusion and releases new energy again. This blows the outer portions away from the star. 3. What is the helium fusion reaction, and why does it require much higher temperatures than hydrogen fusion? Why will helium fusion in the Sun begin with a helium flash? Helium fusion reaction is when 3 helium nuclei become one carbon nucleus. Helium has 2 protons which means greater positive charge. This is needed more speed for strong force to overcome electromagnetic repulsion resulting in greater temperature. 4. Why does the H-R diagram of a globular cluster show a horizontal branch ? What are the characteristics of the stars on the horizontal branch? After the helium flash, stars become hotter, smaller, and less luminous. It is horizontal because the stars have the same luminous. It is horizontal because the stars have the same luminosity, but different surface temperature. 5. What happens to a low-mass star after it exhausts its core helium? Why can't it fuse carbon into heavier elements? The star dies, carbon fusion requires temperatures near 600 million K. Degeneracy pressure stops that from happening.

6. What is a planetary nebula ? What happens to the core of a star after a planetary nebula occurs? A planetary nebula is a shell of gas expanding away from carbon core and ionized by the ultraviolet radiation of the hot carbon core, which makes it glow. 7. Summarize the stages of life that we see on the Sun's life track. Be sure to explain both the changes that occur in the Sun's core with each stage and the changes that are observable from outside the Sun. Main sequence is when hydrogen burning in the core then sub giant/ red giant which ro core contacts, hydrogen shell burning, helium flash leads to helium burning, red increased radius and luminosity , gravitational equilibrium reached again, then double shell burning leads to expansion, which equals to brighter and bigger outer resulted with the outer layers blown into planetary nebula. 8. A) True/False: The iron in my blood came from a star that blew up more than 4 billion years ago. true false b) Explain your reasoning. It is but because all elements except hydrogen and helium were produced in stars. 9. A) True/False: Humanity will eventually have to find another planet to live on, because one day the Sun will blow up as a supernova. true false b) Explain your reasoning. False because the sun will not explode, but it will be a white dwarf after going through the phases of red giant. 10. A) True/False: I sure am glad hydrogen has a higher mass per nuclear particle than many other elements. If it had the lowest mass per nuclear particle, none of us would be here. true false B) Explain your reasoning.

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