Kinematics of the Central Stars Powering Bowshock Nebulae and the Large Multiplicity Fraction of Runaway OB Stars

Abstract

OB stars powering stellar bowshock nebulae (SBNe) have been presumed to have large peculiar velocities. We measured peculiar velocities of SBN central stars to assess their kinematics relative to the general O star population using $Gaia$ EDR3 data for 267 SBN central stars and a sample of 455 Galactic O stars to derive projected velocities $v_{2D}$. For a subset of each sample we obtained new optical spectroscopy to measure radial velocities and identify multiple-star systems. We find a minimum multiplicity fraction of 36$\pm$6% among SBN central stars, consistent with $>$28% among runaway Galactic O stars. The large multiplicity fraction among runaways implicates very efficient dynamical ejection rather than binary-supernova origins. The median $v_{2D}$ of SBN central stars is $v_{2D}$=14.6 km s${}^{-1}$, larger than the median $v_{2D}$=11.4 km s${}^{-1}$ for non-bowshock O stars. Central stars of SBNe have a runaway ($v_{2D}$$>$25 km s${}^{-1}$) fraction of 24${}_{-7}^{+9}$%, consistent with the 22${}_{-3}^{+3}$% for control-sample O stars. Most (76%) of SBNe central stars are not runaways. Our analysis of alignment (${\Delta }_{\mathrm{PA}}$) between the nebular morphological and $v_{2D}$ kinematic position angles reveals two populations: a highly aligned (${\sigma }_{PA}$=25${}^{\circ }$) population that includes stars with the largest $v_{2D}$ (31% of the sample) and a random (non-aligned) population (69% of the sample). SBNe that lie within or near HII 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 new conceptual approach to computing the Solar LSR motion, yielding [U${}_{\odot }$, V${}_{\odot }$, W${}_{\odot }$]= [5.5, 7.5, 4.5] km s${}^{-1}$.

arXiv commentAccepted for publication in AAS journals

References in corpus (73)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• Validation of the new Hipparcos reduction
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• Gaia Data Release 2: The astrometric solution
• Local Kinematics and the Local Standard of Rest
• Local stellar kinematics from Hipparcos data
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• The Proper Motion of Sgr A*: II. The Mass of Sgr A*
• Trigonometric Parallaxes Of High-Mass Star Forming Regions: Our View Of The Milky Way
• SB9: The Ninth Catalogue of Spectroscopic Binary Orbits
• The Galactic O-Star Spectroscopic Survey (GOSSS). II. Bright Southern Stars
• The Galactic O-Star Spectroscopic Survey. I. Classification System and Bright Northern Stars in the Blue-Violet at R~2500
• Gas expulsion and the destruction of massive young clusters
• On the origin of the O and B-type stars with high velocities II Runaway stars and pulsars ejected from the nearby young stellar groups
• Massive stars in massive clusters II: Disruption of bound clusters by photoionization
• A catalogue of young runaway Hipparcos stars within 3kpc from the Sun
• Kinematics and history of the solar neighbourhood revisited
• Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey
• Runaway stars as progenitors of supernovae and gamma-ray bursts
• Massive runaways and walkaway stars
• The Origin of Massive O-type Field Stars. Part II: Field O stars as runaways
• Milky Way Mass Models for Orbit Calculations
• The Galactic O-Star Spectroscopic Survey (GOSSS). III. 142 additional O-type systems
• The origin of runaway stars
• The properties of dynamically ejected runaway and hyper-runaway stars
• Rotational Velocities For B0-B3 Stars in 7 Young Clusters: Further Study of the Relationship between Rotation Speed and Density in Star-Forming Regions
• Gaia Early Data Release 3: Acceleration of the solar system from Gaia astrometry
• E-BOSS: an Extensive stellar BOw Shock Survey. I: Methods and First Catalogue
• Search for OB stars running away from young star clusters. I. NGC 6611
• Dependency of dynamical ejections of O stars on the masses of very young star clusters
• Computing the dust distribution in the bowshock of a fast moving, evolved star
• A comprehensive search for stellar bowshock nebulae in the Milky Way: a catalog of 709 mid-infrared selected candidates
• Models of the circumstellar medium of evolving, massive runaway stars moving through the Galactic plane
• Modeling Nonaxisymmetric Bow Shocks: Solution Method and Exact Analytic Solutions
• Validation of the accuracy and precision of Gaia EDR3 parallaxes with globular clusters
• A search for Galactic runaway stars using Gaia Data Release 1 and Hipparcos proper motions
• Interstellar Weather Vanes: GLIMPSE Mid-Infrared Stellar-Wind Bowshocks in M17 and RCW49
• E-BOSS: An Extensive stellar BOw Shock Survey. II. Catalogue second release
• Characterizing and correcting the proper motion bias of the bright Gaia EDR3 sources
• MONOS: Multiplicity Of Northern O-type Spectroscopic systems. I. Project description and spectral classifications and visual multiplicity of previously known objects
• The Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC (RIOTS4)
• OB Stars & Stellar Bowshocks in Cygnus-X: A Novel Laboratory Estimating Stellar Mass Loss Rates
• Blowing in the wind: The dust wave surrounding $\sigma$ Ori AB
• The Milky Way Project Second Data Release: Bubbles and Bow Shocks
• Modeling the Infrared Bow Shock at delta Velorum: Implications for Studies of Debris Disks and lambda Bootis Stars
• Resolved Kinematics of Runaway and Field OB Stars in the Small Magellanic Cloud
• Core-Collapse Supernovae in Binaries as the Origin of Galactic Hyper-Runaway Stars
• A dearth of short-period massive binaries in the young massive star forming region M17: Evidence for a large orbital separation at birth?
• On the observability of bow shocks of Galactic runaway OB stars
• A Spectroscopic Study of Field and Runaway OB Stars
• The asymmetric drift, the local standard of rest, and implications from RAVE data
• To see or not to see a Bow Shock: Identifying Bow Shocks with H-Alpha Allsky Surveys
• Massive stars in the hinterland of the young cluster, Westerlund 2
• New massive members of Cygnus OB2
• The enigmatic He-sdB pulsator LS IV$-$14${}^{\circ }$116: new insights from the VLT
• Radiation-pressure-driven dust waves inside bursting interstellar bubbles
• A Catalog of New Spectroscopically Confirmed Massive OB Stars in Carina
• 4U 1907+09: a HMXB running away from the Galactic plane
• Bow shocks, bow waves, and dust waves. I. Strong coupling limit
• IR nebulae around bright massive stars as indicators for binary interactions
• Modelling multi-wavelength observational characteristics of bow shocks from runaway early type stars
• Demonstration of a novel method for measuring mass-loss rates for massive stars
• Serendipitous Discovery of An Infrared Bow Shock Near PSR J1549-4848 with Spitzer
• TYC 3159-6-1: a runaway blue supergiant
• Escape from the Bermuda cluster: orphanization by multiple stellar ejections
• An O2If* star found in isolation in the backyard of NGC 3603
• Analysis of the Velocity Field of F and G Dwarfs in the Solar Neighborhood as a Function of Age
• Spectral Types of Field and Cluster O-Stars
• High Velocity Runaway Binaries from Supernovae in Triple Systems
• LP 543-25: a rare low-mass runaway disk star