摘要：OB stars powering stellar bowshock nebulae (SBNe) have been presumed to have large peculiar velocities. Wemeasured peculiar velocities of SBN central stars to assess their kinematics relative to the general O-star populationusing Gaia EDR3 data for 267 SBN central stars and a sample of 455 Galactic O stars to derive projected velocitiesv2D. For a subset of each sample, we obtained new optical spectroscopy to measure radial velocities and identifymultiple-star systems. We find a minimum multiplicity fraction of 36% ± 6% among SBN central stars, consistentwith >28% among runaway Galactic O stars. The large multiplicity fraction among runaways implicates veryefficient dynamical ejection rather than binary-supernova origins. The median v2D of SBN central stars isv2D = 14.6 km s−1, larger than the median v2D = 11.4 km s−1 for non-bowshock O stars. Central stars of SBNehave a runaway (v2D > 25 km s−1) fraction of 24 79-+ %, consistent with the 22 33-+ % for control-sample O stars. Most(76%) SBNe central stars are not runaways. Our analysis of alignment (ΔPA) between the nebular morphologicaland v2D kinematic position angles reveals two populations: a highly aligned (σPA = 25°) population that includesstars with the largest v2D (31% of the sample) and a random (nonaligned) population (69%). SBNe that lie withinor near H II regions comprise a larger fraction of this latter component than SBNe in isolated environments,implicating localized ISM flows as a factor shaping their orientations and morphologies. We outline a newconceptual approach to computing the solar local standard of rest motion, yielding [Ue, Ve, We] = [5.5, 7.5,4.5] km s−1.
