Massive stars before and on the main sequence

Stars more than eight times as massive as the Sun are considered massive. These stars end their lives in violent explosions called supernovae. In these explosions they significantly perturb their surroundings. Additionally, during their lives they also ionize the surrounding interstellar medium through their strong radiation fields.This same radiation also causes the stars to blow away their own surface layers in a stellar outflow or wind. Stars can lose a significant fraction of their initial mass as a result of these winds, affecting their evolution. Through this wind and the supernova at the end of their life, massive stars enrich galaxies with heavy chemical elements formed in the nuclear fusion. To fully understand the impact of massive stars their formation, initial properties, and life need to be properly understood. Therefore, we study the circumstellar disks of two Galactic pre-main-sequence stars. We find their masses to be significantly smaller than the mass of the central stars. Additionally, the disks show signs of perturbation and are consistent with reaching down to the stellar surface. We perform a monte carlo analysis of the binary properties of a set of stellar clusters and find a trend in binary period with stellar age. Further analysis of the youngest cluster, M17, reveals the outcome of massive star formation and empirically confirms the location of the ZAMS for stars above 10 solar masses. Finally, a study of clumped stellar winds at different metallicities shows a trend in both luminosity and metallcity in the wind luminosity relation