Stars form in massive, multi-light-year wide clouds of gas. However, this gas must be stable for stars to form. Galactic nuclei, while containing the right amount of gas to trigger star formation, the rapid changes in star orbits around the center make star formation very hard. It isn’t impossible though, as Robert Maiolino and others at the University of Cambridge have found out. When they observed a galaxy merger in the southern constellation Tucana, they detected stars in the large jets of gas being propelled out of the center of the merger. These stars were determined to be a few million years old, and were being affected by the gravity of the main galaxy.
Most of these stars were determined to be sunlike in two ways: luminosity, and mass. The luminosity contrasts with the rest of the galaxy and can also be partially measured through it’s mass. Since many of these young stars are interacting with one another (and the center of the main galaxy), mass determination is very accurate.