Program: GN-2014A-Q-89

Within the Galaxy's central 30 pc are three of the most massive resolved young clusters in the Local Group (Central Cluster, Arches and Quintuplet). The recent detection of a large number of apparently isolated massive stars within the inner 100 pc of the center has raised fundamental questions regarding massive star formation in a such a dense and harsh environment. Are these isolated stars the results of tidal interactions between clusters, are they escapees from a disrupted cluster, or do they represent a new mode of massive star formation in isolation? Spectroscopic studies of these objects yielding stellar properties, ages, abundances, and radial velocities can differentiate among these scenarios. Interestingly, most of the isolated massive stars have spectral analogs in the Quintuplet Cluster. We have been engaged since 2010 in a combined analysis of the infrared spectra of both selected Quintuplet stars and the isolated massive stars using Gemini spectroscopy. Using our recently developed techniques to derive absolute alpha-elements (Si, Mg) and iron abundances in LBVs and WR stars we are able to trace the imprints of a top-heavy star formation scenario (alpha vs iron) in the Galactic Center. This proposal aims at completing our program. GNIRS has demostrated excellent performance, especially at the shorter NIR wavelengths where extinction to the Galactic center is high, and is allowing us to pioneer the spectral coverage of stars in the Galactic center to the H band and even the J band, where important diagnostic lines are available.