The black hole at the center of the Milky Way galaxy is known as Sagittarius A* (Sgr A*). While the exact details of its formation are still a subject of ongoing research, it is generally believed that Sgr A* formed from the collapse of a massive star.
The initial mass of the star that gave rise to Sgr A* is estimated to have been much larger than the mass of our Sun. However, determining the precise mass is challenging due to the lack of direct observations of the progenitor star.
Based on various observational constraints and theoretical models, scientists estimate that the initial mass of the star could have been anywhere between 20 to 100 times the mass of the Sun. Some estimates suggest that it may have been around 40,000 to 100,000 times the mass of the Sun.
It's important to note that the formation of supermassive black holes like Sgr A* is still an active area of research, and ongoing studies and observations continue to refine our understanding of their origins and the properties of their progenitor stars.