1. To test your understanding of star formation in the spiral density wave model, do Interactive Exercise 16-4 on the Web. You can print out your results, if required. 2. What is a double-radio source...

1. To test your understanding of star formation in the spiral density wave model, do Interactive Exercise 16-4 on the Web. You can print out your results, if required.

2. What is a double-radio source seen along one axis of a jet called? a. BL Lac object b. quasar c. active galaxy d. double-radio source (e) pulsar