Many galaxies host pronounced circumnuclear starbursts, fuelled by infalling gas. Such activity is expected to drive the secular evolution of the nucleus and generate super winds, while the intense radiation fields and extreme gas and cosmic ray densities present may act to modify the outcome of star formation with respect to more quiescent galactic regions. The centre of the Milky Way is the only example of this phenomenon where, by virtue of its proximity, individual stars may be resolved. Previous studies have revealed that it hosts a rich population of massive stars; these are located within three clusters, with an additional contingent dispersed throughout the Central Molecular Zone (CMZ). We employed VLT+KMOS to obtain homogeneous, high S/N spectroscopy of the later cohort for classification and quantitative analysis. Including previously identified examples, we found a total of 83 isolated massive stars within the Galactic Centre, which are biased towards objects supporting powerful stellar winds and/or extensive circumstellar envelopes. No further stellar clusters, or their tidally stripped remnants, were identified, although an apparent stellar overdensity was found to be coincident with the Sgr B1 star forming region. The cohort of isolated massive stars within the CMZ is comparable in size to that of the known clusters but, due to observational biases, is likely highly incomplete at this time. Combining both populations yields over 320 spectroscopically classified stars that are expected to undergo core collapse within the next 20Myr. Given that this is presumably an underestimate of the true number, the population of massive stars associated with the CMZ appears unprecedented amongst star formation complexes within the Milky Way, and one might anticipate that they play a substantial role in the energetics and evolution of the nuclear region.
Constraining the Galactic Center Dark Cluster with ELT/MICADO Observations
Canadian Institute for Theoretical Astrophysics, University of Toronto（多伦多大学理论天体物理研究所）；Max Planck Institute for Radioastronomy（马克斯·普朗克射电天文研究所）；Department of Theoretical Physics and Astrophysics, Masaryk University（马萨里克大学理论与天体物理学系）
