A Structural and Spectroscopy Study of the Clusters Surrounding the Orion Nebula: NGC 1977 and NGC 1981

Open clusters (OCs) belonging to star-forming complexes are the leftovers from the initial stellar generations. Among the various star-forming regions, the Orion complex stands out as an excellent laboratory for studying the high mass star formation process due its proximity and richness in ongoing star formation activities. NGC 1981 is a young OC located northward from the Orion Nebula that inhabits a relatively dust-free field, perhaps as a consequence of the feedback from its massive stellar content, while NGC 1977, located about 20' southwards of NGC 1981, remains embedded within its progenitor cloud. Aiming to deepen the understanding on the star formation and astrophysical processes occurring in NGC 1981 and NGC 1977, we have used astrometric and photometric data from Gaia to characterize them. We also have performed a metallicity and radial velocity characterization of the brightest stars of NGC 1981 through medium resolution spectroscopic data collected at OPD, CASLEO and from the Apogee archive. The spectroscopic data was necessary to improve the membership assignment because the brightest stars (early B type stars) of NGC 1981 exhibit a notable dispersion in the astrometric space, since the cluster may be in dissolution process. This data can also provide insights of the probable formation scenario of the clusters. In the near future, we aim to collect high resolution spectroscopy of the B stars of NGC 1981 and NGC 1977 to solve the interstellar medium components and complement with polarimetric data to unveil the star formation history of the region.