AST 100 HW 7 Light and Sun : Due Tues April 10

1.     Complete the short assignment in Mastering Astronomy called Sun. A record of your work will be sent to me.

2.     Stellar Temperatures: Two stars are the same size and the same distance away but they have different temperatures. Ariel has a temperature of 3000 K and Gwen has a temperature of 8000 K.

á      Sketch the spectrum of light that would result from dispersing the light of these two stars with a diffraction grating, i.e, make a graph of brightness against wavelength. Put both stars on the same graph. (Numbers not necessary, but include axis labels and arrows indicating direction of larger values)

á      Which star is redder?

á      Which star is brighter?

3.     Stellar Sizes. There are 3 stars, all with the same temperature, but different sizes. The stars are ½, 4 and 8 times the radius of the sun.

á      How do they differ in color?

á      How do they differ in brightness?

4.     In Mastering Astronomy, go to the Study Area for Chapter 10: Our Star and find the Visual Quiz. It has 10 questions, repeated here.  After each question, write the correct answer, using words, not bullet number.

1.     The arrows in this diagram are meant to show how gravitational equilibrium works in the Sun. What do the different colors and different arrow lengths represent?

2.     What layer of the Sun are we seeing in this photo?

3.     The dark spots in this photo (such as the one indicated by the arrow) represent what we call

4.     Which photo shows Earth correctly scaled in comparison to the Sun?

5.     This photograph shows a small portion of the Sun's photosphere. What is going on in the bright regions (such as the bright region indicated by the arrow)?

6.     This X-ray image shows a loop of hot gas above the surface of the Sun. If we took a visible light photo that looked in the Sun's photosphere just under the two points where the loop of gas comes down (arrows), what would we find?

7.     You can skip this one- there is no way to tell whether the loop will expand or contract. It will do one or the other.

8.     What layer of the Sun are we seeing in this photograph, and in what wavelength band was it photographed?

9.     What do the yellow regions represent in this photograph?

10. Study this figure and its axis labels. What is this graph showing us?

5.     Go to NASA's Sun-Earth pages and choose one of the latest videos.  Give its name and describe its content. Include a sketch of the key idea in the video.

6.     In NASA's Sun-Earth pages, go to the article on Modeling Extreme Space Weather. Watch the video, read the article and answer these questions.

á      What is a Coronal Mass Ejection (CME)?

á      What is a geomagnetically induced current (GIC)?

7.     Read about the 1859 Solar Superstorm herehere, and here.