80 citations · 152 across the 6 of their papers we have counts for
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astro-ph.SR2016★ 15 cited
Optical Spectra of Ultracool Dwarfs with the Southern African Large Telescope
C. Koen, B. Miszalski, P. Väisänen +1
New spectra of 81 ultracool dwarfs (spectral types M7 and later) are discussed. Spectral classifications of 49 objects are available in the literature, while 32 objects are newly c…
astro-ph.SR2014★ 23 cited
Two candidate brown dwarf companions around core helium-burning stars
V. Schaffenroth, L. Classen, K. Nagel +4
Hot subdwarf stars of spectral type B (sdBs) are evolved, core helium-burning objects. The formation of those objects is puzzling, because the progenitor star has to lose almost it…
astro-ph.SR2011★ 1 cited
Low-mass stellar and substellar companions to sdB stars
S. Geier, L. Classen, P. Bruenner +9
It has been suggested that besides stellar companions, substellar objects in close orbits may be able to trigger mass loss in a common envelope phase and form hot subdwarfs. In an…