An $\ion{H}{i}$ interstellar bubble linked to the O-type stars BD +24°3866 and BD +25°3952

Abstract

We investigate the ISM in the vicinity of the O-type stars BD +24°3866 (O8.5II(f)), BD +24°3881 (O6.5III(f)) and BD +24° 3952 (O8) based on radio continuum and Hi line data obtained with the Synthesis Telescope of the Dominion Radio Astrophysical Observatory (DRAO) with synthesized beams of 1$\farcm$ 5 and 7´ at 1420 and 408 MHz, respectively. High angular resolution IRAS data ( HIRES ) are also analyzed. BD +24°3866 is found to be located close to the inner border of a slowly expanding shell. The evolved Hii region Sh2-88, which is excited by BD +25°3952, appears to be interacting with neutral material in the approaching part of this shell. The whole structure is at a distance of 2.4 kpc and is about 23$\times$15 pc in radius. The total swept up mass is 1300 $M_\odot$. The stellar winds of BD +24°3866 and BD +25°3952, are mainly responsible for shaping the Hi structure. An Hi expanding shell was also found to be related to the Hii region G61.7+0.9. At a kinematic distance of 2.4 kpc, this feature is 10 pc in radius and has neutral and ionized masses of 200 and 135 $M_\odot$, respectively. The present observational data do not allow us to identify a definite interstellar Hi feature associated with BD +24°3881. We consider different explanations for this fact.