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Chapter 19 Homework

Course Materials are always under revision! Weblecture content may change anytime prior to two weeks before scheduled chat session for content.

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Scholars Online Astronomy - Chapter 19: Main Sequence Stars


Reading Preparation

Reading: Astronomy, Chapter 19: On and after the Main Sequence

Study Guide

Key Formulae to Know

Helium Triple-α reaction He + He → Be
He + Be → C
He + C → O
He: Helium
Be: Beryllium
C: Carbon
O: Oxygen
Main Sequence Lifetime as a function of Mass t   =   fM c 2 L t: time
f: fraction of stars mass converted into energy by hydrogen fusion
M: total mass of star
c: speed of light
L: luminosity

Web Lecture

Read the following weblecture before chat: Stars in Mid-Life

Study Activity

Planetarium Program: Use your planetarium program to explore stars at different stages.

  • Center on the Ptolemy cluster and adjust the sky display to about 12° x 10°. Use the status options to turn on the H-R diagram for all the stars in the picture. Adjust the H-R diagram options to display the diagram and star plots using spectral type.
  • Chose 5 stars and hover over each of them. Two stars should be in the cluster. The other three stars should be definitely not in the cluster (chose large stars of different colors.) From the information popup of each star note the
    • Radius
    • Luminosity
    • Spectral Class
    • Location on the HR diagram.
    • Estimate the star's age from the data you've collected.

Website of the Week: Read about the Main sequence stars at the Australia Telescope National Facility site.

Chapter Quiz

Lab Work

Read through the lab for this week; bring questions to chat on any aspect of the lab, whether you intend not perform it or not. If you decide to perform the lab, be sure to submit your report by the posted due date.