The Milky Way galaxy is composed of millions of stars in a relatively flat structure containing a thin disk and a thick disk. Based on computer simulations and analysis of data on the brightness, position, and chemical composition of about 250,000 stars in the thick disk (collected from two telescopes, one in China and one orbiting in space), astrophysicists Maosheng Xiang and Hans-Walter Rix claim that the thick disk of the Milky Way formed in two distinct phases rather than a single one.

Which finding, if true, would most directly support the researchers' claim?

Question

Accepted Answer

There's an age difference of about 2 billion years between certain stars in the thick disk.

Answer

The telescopes used by the researchers have detected stars of similar ages in galaxies other than the Milky Way.

Answer

The thin disk contains about twice as many stars that can be seen from Earth as the thick disk does.

Answer

The stars in the Milky Way tend to have very similar chemical compositions.