The Quintuplet Cluster ⋆ I . A K - band spectral catalog of stellar sources

Context. Three very massive clusters are known to reside in the Galactic Center region, the Arches cluster, the Quintuplet cluster and the Central Parsec cluster, each of them being rich in young hot stars. With new infrared instruments this region is no longer obscured to the observer. Aims. For understanding these very massive clusters, it is essential to know their stellar inventory. We provide comprehensive spec-troscopic data for the stellar population of the Quintuplet cluster that will form the basis of subsequent spectral analyses. Methods. Spectroscopic observations of the Quintuplet cluster have been obtained with the Integral Field Spectrograph SINFONI-SPIFFI at the ESO-VLT. The inner part of the Quintuplet cluster was covered by 22 slightly overlapping fields, each of them of 8 ′′ × 8 ′′ in size. The spectral range comprises the near-IR K-band from 1.94 to 2.45 µm. The 3D data cubes of the individual fields were flux-calibrated and combined to one contiguous cube, from which the spectra of all detectable point sources were extracted. Results. We present a catalog of 160 stellar sources in the inner part of the Quintuplet cluster. The flux-calibrated K-band spectra of 98 early-type stars and 62 late-type stars are provided as Online Material. Based on these spectra, we assign spectral types to all detected sources and derive synthetic K s-band magnitudes. Our sample is complete to about the 13th K-magnitude. We report the detection of two hitherto unknown Wolf-Rayet stars of late WC type (WC9 or later). Radial velocities are measured and employed to asses the cluster membership. The quantitative analysis of the early-type spectra will be subject to a subsequent paper. Key words. Catalog – Galaxy: center – open cluster and associations: individual (Quintuplet) – Infrared: stars – Stars: late type – Stars: early type – Stars: Wolf-Rayet