The R136 star cluster dissected with Hubble Space Telescope/STIS. I. Far-ultraviolet spectroscopic census and the origin of HeII 1640 in young star clusters

Understand

We introduce a HST/STIS stellar census of R136a, the central ionizing star cluster of 30 Doradus.

• We present low resolution far-ultraviolet STIS/MAMA spectroscopy of R136 using 17 contiguous 52x0.2 arcsec slits which together provide complete coverage of the central 0.85 parsec (3.4 arcsec).
• We provide spectral types of 90% of the 57 sources brighter than m_F555W = 16.0 mag within a radius of 0.5 parsec of R136a1, plus 8 additional nearby sources including R136b (O4\,If/WN8).
• We measure wind velocities for 52 early-type stars from CIV 1548-51, including 16 O2-3 stars.