Astron. Astrophys. 338, L91-L94 (1998)

4. Discussion: a evolutionary status of SPH 2

Conti and Massey (1989) present a spectrophotometric study for nearly all Wolf-Rayet stars in our Galaxy and in the Large Magellanic Cloud. They present a list of some WN stars that shows C IV 5808 Å stronger than a normal WN star. In their Fig. 5, the logarithm of the equivalent width of C IV 5808 Å versus the logarithm of the equivalent width of He II 4686 Å shows a clear difference between normal WN stars and WN/WC stars. Here, we reproduce their plot (Fig. 3) with a inclusion of SPH 2. We can see that SPH 2 occupies the locus halfway of the two groups. This indicates that SPH 2 lies in a transition stage between WN and WN/WC. This scenario will be further investigated with an atmospheric model including nitrogen and carbon lines in a following paper.

Fig. 3. Log of equivalent width of He II 4686 versus log of equivalent width of C IV 5808 as given by Conti and Massey (1989). Empty circles represent galactic WN stars and full circles WN/WC stars. SPH 2 is the star in the middle of the diagram.

© European Southern Observatory (ESO) 1998

Online publication: September 17, 1998
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