Search for HI bubbles around WR stars: HD 50896

Based on observations of HI 21 cm line emission we have detected a neutral gas bubble surrounding the WR star HD 50896 and its optical ring nebula S 308. The observations were carried out with the 30 m dish antenna of IAR. We have studied the HI gas distribution in the region 233°≤ l ≤237°, -12°≤ b ≤ -9°, within the velocity range (-70, +140) km/s with a resolution of 2 km/s. The HI bubble that we have found has its maximum extension at the velocity of +8 km/s, indicating a kinematical distance of 1 kpc, which is similar to the optical distance of the open cluster CR 121. At this distance, the dimensions of the bubble are 25 x 35 pc. Our neutral gas observation suggest that HD 50896 belongs to Cr 121 and has Mᵥ=-3.3.Asociación Argentina de Astronomí