Astronomy current events question: recent planetary collision

Astronomy 210L, Fall Semester 2009
Cuesta College, San Luis Obispo, CA

Students are assigned to read online articles on current astronomy events, and take a short current events quiz during the first 10 minutes of lab. (This motivates students to show up promptly to lab, as the time cut-off for the quiz is strictly enforced!)

K. Beatty, "Exoplanets' 'Demolition Derby,'" August 11, 2009
http://www.skyandtelescope.com/news/52978747.html

What evidence did scientists at the Applied Physics Laboratory observe to determine that two planets around star HD 172555 recently collided?
(A) Very large planetary fragments.
(B) The star HD 172555 no longer wobbles.
(C) A sudden end to radio signals of presumably technological origin.
(D) A bright flash from the collision event.
(E) Infrared light emitted from dust.

Correct answer: (E).

Student responses
Sections 70178, 71086, 70200
(A) : 10 students
(B) : 3 students
(C) : 2 students
(D) : 3 students
(E) : 46 students