Study of the late nitrogen-sequence Galactic Wolf-Rayet star WR156. Spectropolarimetry and modeling

For the first time spectropolarimetric observations of Wolf-Rayet star WR156 (WN8h sub-class) were conducted. Medium resolution spectropolarimetric data in the range of 3500-7200 ÅÅ were obtained at 6-m BTA telescope of Special Astrophysical Observatory RAS (SAO RAS) using recently commissioned SCORPIO-2 spectrograph. These data show that the light from the star is significantly polarized, with the degree of polarization P=1.38±0.06%, and the position angle Θ=77.4°±1.2°. This polarization is, most probably, has an interstellar origin, as its magnitude and orientation are similar to the ones of field stars. Also, we present results of numerical modeling of WR156 atmosphere performed using cmfgen code. According to it, WR156 is the richest hydrogen Wolf-Rayet star of WN8 type in the Galaxy.