Five More Massive Binaries in the Cygnus Ob2 Association

Kiminki, Daniel C.; Kobulnicky, Henry A.; Gilbert, Ian; Bird, Sarah; Chunev, Georgi

doi:10.1088/0004-6256/137/6/4608

Cited by 32 publications

(43 citation statements)

References 45 publications

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“…Assuming the system avoids merger, it is likely to evolve through an extreme B supergiant/LBV phase into a long period WR+WR binary configuration as mass loss via stellar winds increases the orbital separation. In combination with the recent work of Kiminki et al (2009) and Kobulnicky & Fryer (2007) the results of our analysis provides additional evidence that Cyg OB2 has a very high fraction of massive binary stars. Such an observational constraint needs to be considered when determining the initial mass function of the association as it may both influence the slope of the relationship and also lead to a population of artificially massive stars, resulting in the inflation of a putative high mass cut-off to the IMF.…”

Section: Discussionsupporting

confidence: 79%

The eclipsing, double-lined, Of supergiant binary Cygnus OB2-B17

Stroud

Clark

Negueruela

et al. 2010

A&A

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Context. Massive, eclipsing, double-lined, spectroscopic binaries are not common but are necessary to understand the evolution of massive stars as they are the only direct way to determine stellar masses. They are also the progenitors of energetic phenomena such as X-ray binaries and γ-ray bursts.Aims. We present a photometric and spectroscopic analysis of the candidate binary system Cyg OB2-B17 to show that it is indeed a massive evolved binary. Methods. We utilise V band and white-light photometry to obtain a light curve and period of the system, and spectra at different resolutions to calculate preliminary orbital parameters and spectral classes for the components. Results. Our results suggest that B17 is an eclipsing, double-lined, spectroscopic binary with a period of 4.0217 ± 0.0004 days, with two massive evolved components with preliminary classifications of O7 and O9 supergiants. The radial velocity and light curves are consistent with a massive binary containing components with similar luminosities, and in turn with the preliminary spectral types and age of the association.

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Section: Discussionsupporting

confidence: 79%

The eclipsing, double-lined, Of supergiant binary Cygnus OB2-B17

Stroud

Clark

Negueruela

et al. 2010

A&A

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“…The mass distribution of the primary stars m p follows a power-law function, f m p (m p ) ∝ m γ p . The distribution of the secondary stars (m s ) or the mass ratio R ≡ m s /m p can be described by two populations: (1) a twin population, i.e., about 40% of binary stars have R ∼ 1, and (2) the remaining binaries, which follow a distribution of f R (R) ∼ constant (Kobulnicky & Fryer 2007;Kiminki et al 2008Kiminki et al , 2009). 3.…”

Section: Initial Settingsmentioning

confidence: 99%

The Galactic Center S-Stars and the Hypervelocity Stars in the Galactic Halo: Two Faces of the Tidal Breakup of Stellar Binaries by the Central Massive Black Hole?

Zhang¹,

Lu²,

Yu³

2013

ApJ

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In this paper, we investigate the link between the hypervelocity stars (HVSs) discovered in the Galactic halo and the Galactic center (GC) S-stars, under the hypothesis that they are both the products of the tidal breakup of the same population of stellar binaries by the central massive black hole (MBH). By adopting several hypothetical models for binaries to be injected into the vicinity of the MBH and doing numerical simulations, we realize the tidal breakup processes of the binaries and their follow-up dynamical evolution. We find that many statistical properties of the detected HVSs and GC S-stars could be reproduced under some binary injecting models, and their number ratio can be reproduced if the stellar initial mass function is top-heavy (e.g., with slope ∼−1.6). The total number of the captured companions is ∼50 that have masses in the range ∼3-7 M and semimajor axes 4000 AU and survive to the present within their main-sequence lifetime. The innermost one is expected to have a semimajor axis ∼300-1500 AU and a pericenter distance ∼10-200 AU, with a significant probability of being closer to the MBH than S2. Future detection of such a close star would offer an important test to general relativity. The majority of the surviving ejected companions of the GC S-stars are expected to be located at Galactocentric distances 20 kpc, and have heliocentric radial velocities ∼−500-1500 km s −1 and proper motions up to ∼5-20 mas yr −1 . Future detection of these HVSs may provide evidence for the tidal breakup formation mechanism of the GC S-stars.

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“…Although massive star formation in Cyg OB2 may not be coeval, studies suggest an age of 3-4 Myr, young enough that the most massive stars are still present and the majority of these stars are still on the main sequence (Hanson 2003). Papers I-VI in this series (Kiminki et al 2007(Kiminki et al , 2008(Kiminki et al , 2009Kobulnicky et al 2012) describe the survey and document orbital parameters for 25 massive binary systems known from the inception of the survey in 1999 through the 2011 observing season. In particular, Paper V provides a high-level overview of the survey's constraints on statistics of massive binary stars by use of a Monte Carlo analysis.…”

Section: Introductionmentioning

confidence: 99%

Toward Complete Statistics of Massive Binary Stars: Penultimate Results From the Cygnus Ob2 Radial Velocity Survey

Kobulnicky

Kiminki

Lundquist

et al. 2014

ApJS

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289

319

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We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P < 45 days, but it is not scale-free. Inflections in the cumulative distribution near 6 days, 14 days, and 45 days suggest key physical scales of 0.2, 0.4, and 1 A.U. where yet-to-be-identified phenomena create distinct features. No single power law provides a statistically compelling prescription, but if features are ignored, a power law with exponent β −0.22 provides a crude approximation over P = 1.4-2000 days, as does a piece-wise linear function with a break near 45 days. The cumulative period distribution flattens at P > 45 days, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P 25 days are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P < 45 days. Completeness corrections imply a binary fraction near 55% for P < 5000 days. The observed distribution of mass ratios 0.2 < q < 1 is consistent with uniform, while the observed distribution of eccentricities 0.1 < e < 0.6 is consistent with uniform plus an excess of e 0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ∼30 km s −1 attributed to atmospheric fluctuations.

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Five More Massive Binaries in the Cygnus Ob2 Association

Cited by 32 publications

References 45 publications

The eclipsing, double-lined, Of supergiant binary Cygnus OB2-B17

The eclipsing, double-lined, Of supergiant binary Cygnus OB2-B17

The Galactic Center S-Stars and the Hypervelocity Stars in the Galactic Halo: Two Faces of the Tidal Breakup of Stellar Binaries by the Central Massive Black Hole?

Toward Complete Statistics of Massive Binary Stars: Penultimate Results From the Cygnus Ob2 Radial Velocity Survey

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