Centrum Astronomii
Wydział Fizyki, Astronomii i Informatyki Stosowanej, Uniwersytet Mikołaja Kopernika

Distance to Wolf-Rayet Star WR 134

Czart K., Strobel A.
2006

Distances to Wolf-Rayet stars are still the subject of research. The only WR star with reliable Hipparcos parallax is WR 11. Other Wolf-Rayet stars have photometric distances estimations. Recently a correlation between equivalent width of interstellar Ca II H (3968 A) and K (3933 A) lines and Hipparcos parallaxes has been found for OB stars (Megier et al. 2005). These relations are given with formulas: pi=1/[2.78EW(K)+95] and pi=1/[4.58EW(H)+102], where pi is a parallax in arcseconds and EW is equivalent width in milliangstroms. We have used these correlations to estimate distance to Wolf-Rayet star WR 134. Equivalent widths of Ca II lines have been measured in low resolution spectra with R=2000. We have got: 1.17 kpc from Ca II H and 1.18 kpc Ca II K line, while distance to this star as cited of VII Catalogue of Wolf-Rayet Stars is 1.74 kpc. If WR 134 belongs to complex of associations around Cyg OB1, distance agree very well with distances to other members of these associations - also obtained from Ca II lines intensities.