the specific identification of the biggest star in the Andromeda Galaxy (M31) is challenging. The Andromeda Galaxy is located approximately 2.5 million light-years away from Earth, and detailed observations of individual stars within it are difficult due to the immense distance.
However, Andromeda is known to host numerous massive stars, similar to our own Milky Way galaxy. Massive stars, often referred to as supergiants or hypergiants, can be significantly larger and more luminous than our Sun. Some examples of known massive stars in the Milky Way include Betelgeuse and Rigel.
In the future, as observational technology and techniques improve, astronomers may gain a better understanding of the specific characteristics of stars in the Andromeda Galaxy, including their sizes. However, as of now, it is challenging to determine the exact identity of the largest star in Andromeda.