KU Car, a young massive eclipsing binary system in NGC 3324

Massive stars are needed engines in the galactic clockwork for the chemical evolution of the Galaxy and the energetic input to the ISM. These stars suffer endemic multiplicity, and thus, studies of the origin and evolution of massive stars is tied to the study of binaries. Therefore, eclipsing binary systems are indispensable objects because absolute parameters (e.g. masses, radii, etc.) can be derived combining the study and modeling of radial velocity and light curves. Such absolute parameters derived from direct observations help to test models about the structure and evolution of massive stars. In this talk, we are presenting an analysis of the light and radial velocity curves of the eclipsing binary system KU Car (P=2.96 d). This binary, composed by a B0.5-0.7 V primary and an unseen companion, shows a remarkable light-curve with a sharp and deep primary minimum and a shallow secondary minimum with strong "reflection effect". Using PHOEBE 2.1 code for modeling, we have derived absolute parameters for both stars proposed the evolutionary stage. This Algol-like system dominated by a young early-B type star, is located in the center of NGC 3324, a bubble-like star-forming region also known as "Gabriela Mistral" Nebula. The photometric analysis is based on multi-band observations obtained using LCOGTN telescopes, and data gathered from ASAS-3, ASAS-SN, TESS, and GDS projects spanning a period of about 18 years. Radial velocities were determined using spectroscopic observations obtained at LCO/duPont and ESO-LSO/2p2 telescopes in the framework of "OWN Survey" and "B-SUGOS" projects.