ISO-Sws Studies of Wolf-Rayet Stars: Neon Abundances

摘要: ISO-sws data of one WN star and four WC stars are presented. The WR 147 (WN8(h)+B0.5 V) show the [CaIv] 3.21 µm, [Sly] 10.5 µm [Netts] 15.5 fine-structure lines. We obtain a terminal wind velocity ~950 km s-1 from helium recombination lines observed infrared Previously derived interstellar extinction values EB_ v ≃ 4.1 mag at Rv 2.7 confirmed. distance to is revised slightly upwards 650 pc, based on galactic LMC WN8-9 calibrators in K-band. spectrum exhibits clear evidence for clumping WN8 star. Using non-LTE, line-blanketed model that allows clumping, we find volume filling factor 10% nicely matches line-profiles, though cannot exclude factors range 4% 25%. This leads mass-loss rate (1.5-3.7) x 10-5My⊙r -1, substantially lower than optical or radio observations under assumptions homogeneity. Additionally including effects line-blanketing, performance factor, Mv ∞ /(L * /c),is reduced ~2.5. Hydrogen severely depleted, but present 9% by mass. Observations [Ca Iv] allow us place constraints surface abundances these elements. In all cases good agreement with cosmic (adjusted hydrogen-poor envi-ronment) thus evolutionary predictions stars, which should not yet exhibit products core-burning stages beyond CNO cycle before reaching phase.