Astronomy current events question: dwarf galaxy NGC 4449

Astronomy 210L, spring semester 2012
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!)

Charles Q. Choi, "Twisted Dwarf Galaxy Warped by Cosmic 'Stealth Merger'," February 8, 2012
http://www.msnbc.msn.com/id/46314513/ns/technology_and_science-space/#.T0w34XLLw0U

The distorted shape and furious star formation rate of dwarf galaxy NGC 4449 may be due to a newly discovered __________ nearby.
(A) dark matter cloud.
(B) supermassive black hole.
(C) dark energy stream.
(D) type II supernova.
(E) smaller dwarf galaxy.

Correct answer: (E)

Student responses
Sections 30678, 30679, 30680
(A) : 3 students
(B) : 9 students
(C) : 1 student
(D) : 6 students
(E) : 31 students