• Publications
  • Influence
The R136 star cluster hosts several stars whose individual masses greatly exceed the accepted 150 M⊙ stellar mass limit
Spectroscopic analyses of hydrogen-rich WN5‐6 stars within the young star clusters NGC 3603 and R136 are presented, using archival Hubble Space Telescope and Very Large Telescope spectroscopy, and
Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions
Evolution and fate of very massive stars
There is observational evidence that supports the existence of very massive stars (VMS) in the local universe. First, VMS (Mini ≲ 320 M⊙) have been observed in the Large Magellanic Clouds (LMC).
The Wolf-Rayet stars in the Large Magellanic Cloud - A comprehensive analysis of the WN class
Context. Massive stars, although being important building blocks of galaxies, are still not fully understood. This especially holds true for Wolf-Rayet (WR) stars with their strong mass loss, whose
The Gaia-ESO Public Spectroscopic Survey
The Gaia-ESO Public Spectroscopic Survey has begun and will obtain high quality spectroscopy of some 100000 Milky Way stars, in the field and in open clusters, down to magnitude 19, systematically ...
The very massive binary NGC 3603-A1
Using Very Large Telescope/Spectrograph for INtegral Field Observation in the Near-Infrared (VLT/SINFONI), we have obtained repeated adaptive-optics assisted, near-infrared spectroscopy of the three
Gemini GMOS spectroscopy of HeII nebulae in M 33
We have carried out a narrow-band survey of the Local Group galaxy, M33, in the HeII λ4686 emission line, to identify HeII nebulae in this galaxy. With spectroscopic follow-up observations, we
4MOST: 4-metre multi-object spectroscopic telescope
Initial design and performance estimates for the wide-field corrector concepts are presented and a full facility simulator is being developed to guide trade-off decisions regarding the optimal field-of-view, number of fibres needed, and the relative fraction of high-to-low resolution fibres.
A RAVE investigation on galactic open clusters. II, Open cluster pairs, groups and complexes
CONTEXT: It is generally agreed upon that stars form in open clusters (OCs) and stellar associations, but little is known about structures in the Galactic OC population; whether OCs and stellar
Two very nearby (d ~ 5 pc) ultracool brown dwarfs detected by their large proper motions from WISE, 2MASS, and SDSS data
Aims. WISE provides an infrared all-sky survey that aims at completing our knowledge on the possibly dramatically increasing number of brown dwarfs with lower temperatures. We search for the nearest