Assignment # 5 Interstellar Medium

ASTR 122, Robert L Zimmerman

Assigned Feb 11, 2007 ---Due Feb 18, 2008

You are asked to return various images and answer a few questions.  You MUST place all images in a word processor and include a description of the images with its URL. You do not have to use the suggested URLs that I give you. 

Questions

1.As described on pages 482 describe the composition of interstellar dust. What is its size and shape? How is the size and shaped determined?

2. Draw the picture on page 494 of how hydrogen atoms produce 21 cm radiation? Make sure the direction of the spins is clear.

3. Explain why molecular hydrogen is not used to in mapping molecular clouds. What molecules are used to map molecular could.

4. Describe the properties of the Local Bubble (ref page 491). Make your explanation sufficiently detailed so it explains how astronomers knew the bubble was there, what created it, and its physical size.

Images

5. Return an image of the proplyds created by the radiation coming from the Orion region. Write a brief description below the picture and its URL. The description must be a minimum of four sentences

http://antwrp.gsfc.nasa.gov/apod/ap961017.html

http://antwrp.gsfc.nasa.gov/apod/ap031115.html

http://antwrp.gsfc.nasa.gov/apod/ap950911.html

http://hubblesite.org/newscenter/archive/releases/2001/13

6. The Eagle Nebula (M16) lies about 6500 light years away and spans about 20 light years. Newborn stars are forming in the Eagle Nebula. Images show evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust. The giant pillars are light years in length and contain regions of star formation. At each pillar’s end the intense radiation of bright young stars causes low-density material to boil away, leaving stellar nurseries of dense EGGs exposed. Return an image of the pillars or "EGGs” in the Eagle Nebula. Write a brief description below the picture and its URL. The description must be a minimum of four sentences. Possible URLs are

http://antwrp.gsfc.nasa.gov/apod/ap030213.html

http://antwrp.gsfc.nasa.gov/apod/ap010812.html

http://antwrp.gsfc.nasa.gov/apod/ap031026.html

What is EGGs an abbreviation for?

7. Jets shoot from dozens of young stars creating glowing compressed shocked waves known as Herbig-Haro objects. Return an image of an HH object. Write a brief description below the picture and its URL. The description must be a minimum of four sentences. Possible URLs are

http://antwrp.gsfc.nasa.gov/apod/ap970619.html

http://antwrp.gsfc.nasa.gov/apod/ap000321.html

http://antwrp.gsfc.nasa.gov/apod/ap000313.html

http://antwrp.gsfc.nasa.gov/apod/ap991129.html