The Origin of OB Runaway Stars

Fujii, Michiko S.; Zwart, Simon Portegies

doi:10.1126/science.1211927

Cited by 172 publications

(186 citation statements)

References 49 publications

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“…In the case of dynamical interaction between massive single and binary stars, a typical ejection velocity is given by v 2 ej = GM b /a (M b = total mass of binary with semi-major axis a) according to Fujii & Portegies Zwart (2011), and the ejected star usually has the lowest mass of the three. By this reasoning, assuming a M 25 M⊙ WR progenitor limit, a M b =50 M⊙ (160 M⊙) binary with a period up to 170d (550d) would be capable of ejecting a WR progenitor star with at least vej = 140 kms −1 .…”

Section: Wr Stars At Large Distances From the Galactic Diskmentioning

confidence: 99%

Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population

Rosslowe

Crowther

2015

Monthly Notices of the Royal Astronomical Society

125

143

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We construct revised near-infrared absolute magnitude calibrations for 126 Galactic Wolf-Rayet (WR) stars at known distances, based in part upon recent large scale spectroscopic surveys. Application to 246 WR stars located in the field, permits us to map their Galactic distribution. As anticipated, WR stars generally lie in the thin disk (∼40 pc half width at half maximum) between Galactocentric radii 3.5-10 kpc, in accordance with other star formation tracers. We highlight 12 WR stars located at vertical distances of 300 pc from the midplane. Analysis of the radial variation in WR subtypes exposes a ubiquitously higher N W C /N W N ratio than predicted by stellar evolutionary models accounting for stellar rotation. Models for non-rotating stars or accounting for close binary evolution are more consistent with observations. We consolidate information acquired about the known WR content of the Milky Way to build a simple model of the complete population. We derive observable quantities over a range of wavelengths, allowing us to estimate a total number of 1200 +300 −100 Galactic WR stars, implying an average duration of ∼ 0.25 Myr for the WR phase at the current Milky Way star formation rate. Of relevance to future spectroscopic surveys, we use this model WR population to predict follow-up spectroscopy to K S ≃ 13 mag will be necessary to identify 95% of Galactic WR stars. We anticipate that ESA's Gaia mission will make few additional WR star discoveries via low-resolution spectroscopy, though will significantly refine existing distance determinations. Appendix A provides a complete inventory of 322 Galactic WR stars discovered since the VIIth catalogue (313 including Annex), including a revised nomenclature scheme.

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Section: Wr Stars At Large Distances From the Galactic Diskmentioning

confidence: 99%

Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population

Rosslowe

Crowther

2015

Monthly Notices of the Royal Astronomical Society

125

143

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“…This is expected, because N-body simulations of massive clusters predict that the fraction of stars expelled by dynamical processes from the clusters may be as high as (20-25)% of O-type stars and (10-15)% of early-B type stars (Fujii & Portegies Zwart 2011;Oh & Kroupa 2016).…”

Section: A Search For Runaway Starsmentioning

confidence: 99%

The little-studied cluster Berkeley 90 – III. Cluster parameters

Marco

Negueruela

2016

Mon. Not. R. Astron. Soc.

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The open cluster Berkeley 90 is the home to one of the most massive binary systems in the Galaxy, LS III +46 • 11, formed by two identical, very massive stars (O3.5 If* + O3.5 If*), and a second early-O system (LS III +46 • 12 with an O4.5 IV((f)) component at least). Stars with spectral types earlier than O4 are very scarce in the Milky Way, with no more than 20 examples. The formation of such massive stars is still an open question today, and thus the study of the environments where the most massive stars are found can shed some light on this topic. To this aim, we determine the properties and characterize the population of Berkeley 90 using optical, near-infrared and WISE photometry and optical spectroscopy. This is the first determination of these parameters with accuracy. We find a distance of 3.5 +0.5 −0.5 kpc and a maximum age of 3 Ma. The cluster mass is around 1 000 M (perhaps reaching 1 500 M if the surrounding population is added), and we do not detect candidate runaway stars in the area. There is a second population of young stars to the Southeast of the cluster that may have formed at the same time or slightly later, with some evidence for low-activity ongoing star formation.

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“…This is based on an estimated age of ∼46 ± 23 Myr and the star's space motion. Fujii & Portegies Zwart (2011) hypothesize that such objects are the result of a three-body interaction that results in the formation of a runaway star and a close binary. HIP 103199 has a wide ( 646 AU) binary companion found by Lépine & Bongiorno 2007, which we classify as M3.5.…”

Section: Hip 103199 (Hd 335289)mentioning

confidence: 99%

WIDE COOL AND ULTRACOOL COMPANIONS TO NEARBY STARS FROM Pan-STARRS 1

Deacon

Liu

Magnier

et al. 2014

ApJ

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We present the discovery of 57 wide (>5 ) separation, low-mass (stellar and substellar) companions to stars in the solar neighborhood identified from Pan-STARRS 1 (PS1) data and the spectral classification of 31 previously known companions. Our companions represent a selective subsample of promising candidates and span a range in spectral type of K7-L9 with the addition of one DA white dwarf. These were identified primarily from a dedicated common proper motion search around nearby stars, along with a few as serendipitous discoveries from our Pan-STARRS 1 brown dwarf search. Our discoveries include 23 new L dwarf companions and one known L dwarf not previously identified as a companion. The primary stars around which we searched for companions come from a list of bright stars with well-measured parallaxes and large proper motions from the Hipparcos catalog (8583 stars, mostly A-K dwarfs) and fainter stars from other proper motion catalogs (79170 stars, mostly M dwarfs). We examine the likelihood that our companions are chance alignments between unrelated stars and conclude that this is unlikely for the majority of the objects that we have followed-up spectroscopically. We also examine the entire population of ultracool (>M7) dwarf companions and conclude that while some are loosely bound, most are unlikely to be disrupted over the course of ∼10 Gyr. Our search increases the number of ultracool M dwarf companions wider than 300 AU by 88% and increases the number of L dwarf companions in the same separation range by 82%. Finally, we resolve our new L dwarf companion to HIP 6407 into a tight (0. 13, 7.4 AU) L1+T3 binary, making the system a hierarchical triple. Our search for these key benchmarks against which brown dwarf and exoplanet atmosphere models are tested has yielded the largest number of discoveries to date.

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The Origin of OB Runaway Stars

Cited by 172 publications

References 49 publications

Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population

Spatial distribution of Galactic Wolf–Rayet stars and implications for the global population

The little-studied cluster Berkeley 90 – III. Cluster parameters

WIDE COOL AND ULTRACOOL COMPANIONS TO NEARBY STARS FROM Pan-STARRS 1

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