A&A 621, A92 (2019) Astronomy https://doi.org/10.1051/0004-6361/201833712 & c ESO 2019 Astrophysics The Galactic WC and WO stars The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors A. A. C. Sander1,2, W.-R. Hamann1, H. Todt1, R. Hainich1, T. Shenar1,3, V. Ramachandran1, and L. M. Oskinova1 1 Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany e-mail:
[email protected] 2 Armagh Observatory and Planetarium, College Hill, Armagh BT61 9DG, UK 3 Institute of Astrophysics, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgium Received 25 June 2018 / Accepted 26 November 2018 ABSTRACT Wolf-Rayet stars of the carbon sequence (WC stars) are an important cornerstone in the late evolution of massive stars before their core collapse. As core-helium burning, hydrogen-free objects with huge mass-loss, they are likely the last observable stage before collapse and thus promising progenitor candidates for type Ib/c supernovae. Their strong mass-loss furthermore provides challenges and constraints to the theory of radiatively driven winds. Thus, the determination of the WC star parameters is of major importance for several astrophysical fields. With Gaia DR2, for the first time parallaxes for a large sample of Galactic WC stars are available, removing major uncertainties inherent to earlier studies. In this work, we re-examine a previously studied sample of WC stars to derive key properties of the Galactic WC population. All quantities depending on the distance are updated, while the underlying spectral analyzes remain untouched.