The possible presence of a very large amount of unseen ("dark")matter in the halo of our Galaxy is deduced from the
A) unexpected absence of luminous matter (stars,etc. )beyond a certain distance.
B) rotation curve of our Galaxy,which indicates higher than expected orbital speeds in the outer regions of the Galaxy.
C) rotation curve of our Galaxy,which shows that orbital speeds in the outer parts of the Galaxy decrease in a way that follows Kepler's law.
D) unexpected high amount of interstellar absorption in certain directions.

Question

Quizplus · Accepted Answer

The rotation curve of our Galaxy shows that stars in the outer regions are rotating around the center of the Galaxy at higher than expected speeds. This indicates the presence of additional mass that cannot be accounted for by the visible matter in the Galaxy, and is therefore likely due to the presence of dark matter in the halo.

The Possible Presence of a Very Large Amount of Unseen