hw6 - Astronomy 121, Spring 2011 Homework 6 due date: March...

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Astronomy 121, Spring 2011 Homework 6 due date: March 11 Reading: Chap. 4-5 Answer in complete sentences and show your calculations. Luminosity and the Stefan-Boltzmann Law 1. (10 pts) In about 6 billion years, our Sun will expand into a huge red star known as a red giant. The red giant will have a radius of about 220 times its original radius. The Sun will cool to a temperature of around 4500 K (giving it the red color). The current temperature of the Sun is 5800 K and the current radius is 7 × 10 8 m. (a) Will the Earth survive the expansion of the Sun into a red giant, or will it be swallowed by the Sun? Show your work. (b) What is the current luminosity of the Sun? Show your calculation and give your answer in Watts. How many 100 W lightbulbs is this? (c) What will be the luminosity of the Sun when it becomes a red giant? 2. (10 pts) A binary star system is a system comprised of two stars in orbit around each other. Albireo is one such system 380 lightyears from Earth. Albireo A is a yellow giant
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This note was uploaded on 03/22/2012 for the course FINA 210 taught by Professor Dakroub during the Spring '12 term at American University in Cairo.

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hw6 - Astronomy 121, Spring 2011 Homework 6 due date: March...

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