Related papers: The most massive stars in the Arches cluster
The massive Arches cluster near the Galactic center should be an ideal laboratory for investigating massive star formation under extreme conditions. But it comes at a high price: the cluster is hidden behind several tens of magnitudes of…
Massive stars are the key agents of feedback. Consequently, quantitative analysis of massive stars are required to understand how the feedback of these objects shapes/ creates the large scale structures of the ISM. The giant HII region N206…
Context. The formation and early evolution of high- and intermediate-mass stars towards the main sequence involves the interplay of stars in a clustered and highly complex environment. To obtain a full census of this interaction, the…
The central region of the Milky Way provides a unique laboratory for a systematic, spatially-resolved population study of evolved massive stars of various types in a relatively high metallicity environment. We have conducted a…
We report Hubble Space Telescope (HST) Near-infrared Camera and Multi-object Spectrometer (NICMOS) observations of the Arches and Quintuplet clusters, two extraordinary young clusters near the Galactic Center. For the first time, we have…
Massive clusters in our Galaxy are an ideal testbed to investigate the properties and evolution of high mass stars. They provide statistically significant samples of massive stars of uniform ages. To accurately determine the intrinsic…
We study the stellar and wind properties of massive stars in the central cluster of the Galaxy. We use non-LTE atmosphere models including winds and line-blanketing to fit their H and K band spectra obtained with the 3D spectrograph SINFONI…
In the last decade star clusters have been found in the centers of spiral galaxies across all Hubble types. We here present a spectroscopic study of the exceptionally bright (10^6 - 10^8 Lsun) but compact (Re ~ 5 pc) nuclear star clusters…
Aims. Having established the binary status of nineteen O-type stars located in four Cygnus OB associations, we now determine their fundamental parameters to constrain their properties and their evolutionary status. We also investigate their…
The outcome of the formation of massive stars is an important anchor point in their evolution. It provides insight into the physics of the assembly process, and sets the conditions for stellar evolution. We characterize a population of 18…
We present observations and analyses of seven Galactic O stars of type O6 and earlier. Analyses are carried out using NLTE plane-parallel, hydrostatic models as well as NLTE spherical models with mass-loss. With detailed calculations for…
A (V,V - I)--diagram for the intermediate-age open cluster NGC 7789 has been derived from CCD observations of more than 15,000 stars within ~ 18 arcmin of the cluster center. From the brightest giants and blue stragglers at V ~ 11 to the…
Based on $K$-band integral-field spectroscopy, we analyze four Wolf-Rayet stars of the nitrogen sequence (WN) found in the inner part of the Quintuplet cluster. All WN stars (WR102d, WR102i, WR102hb, and WR102ea) are of spectral subtype…
Massive BA-type supergiants are among the visually brightest stars in galaxies with active star formation. As such they are versatile tools for studies of stellar and galactochemical evolution. Moreover, they can act as distance indicators…
Deep Keck/NIRC2 HK'L' observations of the Arches cluster near the Galactic center reveal a significant population of near-infrared excess sources. We combine the L'-band excess observations with K'-band proper motions, to confirm cluster…
We identified star clusters in archived HST/WFPC2 images of the merger and ultra-luminous infrared galaxy NGC 6240, with the aim of investigating whether star cluster properties (luminosity, age and mass) in such an extreme environment…
As deep spectroscopic campaigns extend to higher redshifts and lower stellar masses, the interpretation of galaxy spectra depends increasingly upon models for very young stellar populations. Here we present new HST/COS ultraviolet…
The cluster Westerlund~1 (Wd1) is host to a large variety of post main-sequence (MS) massive stars. The simultaneous presence of these stars can only be explained by stellar models if the cluster has a finely-tuned age of 4-5Myr, with…
The striking broad emission line spectroscopic appearance of Wolf-Rayet (WR) stars has long defied analysis, due to the extreme physical conditions within their line and continuum forming regions. Recently, model atmosphere studies have…
We have studied the optical spectra of a sample of 31 O- and early B-type stars in the Small Magellanic Cloud, 21 of which are associated with the young massive cluster NGC 346. Stellar parameters are determined using an automated fitting…