Final answer:
The oldest members of the Milky Way galaxy are the globular clusters, with a minimum age of about 11 billion years, which helps estimate the age of the Galaxy and universe.
Step-by-step explanation:
The oldest members of the Milky Way galaxy are the globular clusters. These ancient groups of stars are some of the first constituents of our Galaxy, dating back to at least 13 billion years ago. They provide a vital clue to the age of the Milky Way itself and are an important aspect of understanding the evolution of galaxies.
Globular clusters are found both in the Milky Way and other galaxies, containing stars referred to as population II stars, which are characterized by having few heavy elements. These stars are considered to be among the oldest structures in the Galaxy, with even the youngest globular clusters being about 11 billion years old. Hence, globular clusters serve as one of the best estimates for the minimum age of the universe itself.