Winds of Massive Stars: High-resolution X-Ray Spectra of Stars in NGC 3603

Abstract

The cluster NGC 3603 hosts some of the most massive stars in the Galaxy. With a modest 50 ks exposure with the Chandra High Energy Grating Spectrometer, we have resolved emission lines in spectra of several of the brightest cluster members, which are of WNh and O spectral types. This observation provides our first definitive high-resolution spectra of such stars in this nearby starburst region. The stars studied have broadened X-ray emission lines, some with blueshifted centroids, and are characteristic of massive stellar winds with terminal velocities around 2000– . X-ray luminosities and plasma temperatures are very high for both the WNh and O-stars studied. We conclude that their X-rays are likely the result of colliding winds.