WK10_Hubble_Deep_Field

A105 – Stars and Galaxies Week 10 Exploration Galaxies in the Hubble Deep Field Learning Goals: Students should be able to:  describe how galaxies are distributed in space.  identify regions of high galaxy density.  interpret an astronomical image. STEP ONE: READ THE FULL ASSIGNMENT ON CANVAS. STEP TWO: Make distance distribution. This is the distance from us, not from one galaxy to another. For each galaxy with a measured redshift (which tells us a distance) in the Hubble image, add an “X” on the line corresponding to its redshift in the table below. Be systematic. If you can print the image it is easier to cross the ones you’ve done. Need to do more than 60 galaxies for full credit [4 pt]. STEP THREE: Answer the questions on the next page. ALL WORK IS INDIVIDUAL Redshift interval Add an “x” for each galaxy that lies in the corresponding redshift interval 0.00 – 0.19 Click here to enter text. 0.20 – 0.39 Click here to enter text. 0.40 – 0.59 Click here to enter text. 0.60 – 0.79 Click here to enter text. 0.80 – 0.99 Click here to enter text. 1.00 – 1.19 Click here to enter text. 1.20 – 1.39 Click here to enter text. 1.40 – 1.59 Click here to enter text. 1.60 – 1.79 Click here to enter text. 1.80 – 1.99 Click here to enter text. 2.00 – 2.19 Click here to enter text. 2.20 – 2.39 Click here to enter text. 2.40 – 2.59 Click here to enter text. 2.60 – 2.79 Click here to enter text. 2.80 – 2.99 Click here to enter text. 3.00 – 3.19 Click here to enter text. 3.20 – 3.39 Click here to enter text. 3.40 – 3.59 Click here to enter text. 3.60 – 3.79 Click here to enter text. 3.80 – 3.99 Click here to enter text. 4.00 – 4.19 Click here to enter text. 4.20 – 4.39 Click here to enter text. NAME: Click here to enter name.

1. Find two galaxies in the image that APPEAR TO BE THE LARGEST AND BRIGHTEST, and list their redshifts below. How do their redshifts (=distances) compare to the redshifts of other random galaxies in the image? [1 pt] Does this explain why they appear largest/brightest? How? (Note that the redshift itself does not make a galaxy be brighter or not - it is just a measure of the distance.) [1 pt] Click here to enter text. 2. Find and examine the two galaxies at redshift = 0.54 in the region where you can see a little square edge. These two galaxies appear different in size. Does this tell us anything about their true sizes? What exactly? [1 pt] Click here to enter text. 3. Look at your table. Are there redshifts intervals (=distances) at which galaxies are more common? List three such redshift intervals. What does this tell you about how galaxies are distributed in space? Is this consisent with the uniform distribution of galaxies in space? [1 pt] Click here to enter text. 4. Look at the lower left part of the image. What are the galaxy types that correspond to galaxies with redshifts 0.54, 0.32, 0.95 (bigger of the two with redshift 0.95) and 0.47, in that order? [2 pt] Click here to enter text. 5. Extra credit. There is a bright star that appears next to the big orange galaxy at redshift 0.52 (also lower left region). There are two possibilities regarding where this star is located (with respect to us and with respect to that galaxy), and depending on that, what the star may represent. What are these two possibilities (or just one)? If you provided both possibilities, which one would you consider more likely? Why? Click here to enter text.