Question

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? choose 1 answer: theres an age difference of about 2 billion years between certain stars in the thick disk. the stars in the milky way tend to have very similar chemical compositions. the thin disk contains about twice as many stars that can be seen from earth as the thick disk does. the telescopes used by the researchers have detected stars of similar ages in galaxies other than the milky way.

Explanation:

• Option A: If there is a large age difference (about 2 billion years) between certain stars in the thick disk, it implies that the thick disk formed in different time - periods (two distinct phases).
• Option B: Similar chemical compositions do not support the claim of two - phase formation. It may suggest a more homogeneous formation process rather than distinct phases.
• Option C: The number of stars visible from Earth in the thin and thick disks has no relation to the formation phases of the thick disk.
• Option D: Detecting stars of similar ages in other galaxies is not relevant to the formation phases of the Milky Way's thick disk.

Answer:

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