SIMBAD references

We present mid-infrared Spitzer Space Telescope Infrared Spectrograph (IRS) spectroscopy of the prototype WN star EZ Canis Majoris (HD 50896, WN4b). Numerous stellar wind lines of He II are revealed, plus fine-structure lines of [Ne III] 15.5 µm and [O IV] 25.9 µm. We carry out a spectroscopic analysis of HD 50896 allowing for line blanketing and clumping, which is compared to the mid-IR observations. We make use of these stellar properties to accurately derive Ne/He=(1.2-1.8)x10^–4 and O/He=(4.2-4.8)x10^–5 by number, for the first time in an early WN star. In addition, we obtain N/C∼40 and N/O∼50 by number, in perfect agreement with current predictions for rotating massive stars at the end of interior hydrogen burning.