Astr 101 – Fall 2013 – Homework Assignment #7
Extrasolar Planets; The Milky Way and Other Galaxies

Provide a full answer to each of the following questions, using full English sentences. Complete answers should be at least 2-3 lines long but (except for Question 1) no more than 5 lines long, and they must all fit in one page. Remember to include a header with your name, the course number, and the assignment number at the top of the page. If you email me your homework, attach it as a separate file. If you submit it on paper, make sure the page has smooth edges.

(1) Choose a star with multiple known planets (at least 5). Name the star, give its type and distance from us, and list its known planets, including for each one the size of the planet and the radius of its orbit around the star. Comment on how this system compares with the Solar System.

(2) Why is it easier for astronomers to discover planets that are larger than the Earth and closer to their star?

(3) Why are astronomers really interested in finding out how fast stars revolve around the center of the galaxy, and why are the results puzzling?

(4) Why do we think that there is a supermassive black hole at the center of our galaxy?

(5) How do we know in which galaxies, and which parts of those galaxies, stars are currently being formed?