Astronomy current events question: horseshoe-shaped gas ring around star HD 142527

Astronomy 210L, spring semester 2013
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!)

Monica Young, "ALMA Minds the (Planet‑Forming) Gap," January 2, 2013
http://www.skyandtelescope.com/news/home/ALMA-Minds-the-Planet-Forming-Gap-185434472.html

The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile has observed an outer horseshoe-shaped gas ring around the young star HD 142527, which may be due to:
(A) the presence of a nearby black hole.
(B) a recent type II supernova explosion.
(C) fluctuations in the star's fusion rate.
(D) the gravitational effect of forming planets.
(E) faulty data processing.

Correct answer: (D)

Student responses
Sections 30678, 30679, 30680
(A) : 6 students
(B) : 8 students
(C) : 12 students
(D) : 33 students
(E) : 0 students