The mass ratio distribution of B-type visual binaries in the Sco OB2 association

Shatsky, N. I.; Tokovinin, Andreï

doi:10.1051/0004-6361:20011542

Cited by 149 publications

(239 citation statements)

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“…05-0.10 (Abt et al 1990;Shatsky & Tokovinin 2002;Hinkley et al 2015;Moe & Di Stefano 2015a), which we exclude when quantifying our multiplicity statistics. Alternatively, other observational methods are sensitive to only companions with q0.3 (Evans et al 2013;Rizzuto et al 2013;Sana et al 2014, see Figure 1).…”

Section: Definitionsmentioning

confidence: 99%

“…Companions to early-type stars can therefore be visually resolved only at larger orbital separations a20 au, i.e., P10 days, even with speckle interferometry (Mason et al 1998(Mason et al , 2009Preibisch et al 1999), adaptive optics (Duchêne et al 2001;Shatsky & Tokovinin 2002;Sana et al 2014), lucky imaging (Peter et al 2012), and space-based observations (Caballero-Nieves et al 2014; Aldoretta et al 2015). MS binaries with large brightness contrasts Δm4mag, and therefore small mass ratios q=M comp /M 1 0.3, can only be detected at even longer orbital periods P10 5 days (see purple region in our Figure 1).…”

Section: Visual Binariesmentioning

confidence: 99%

“…For a sample of  = 115 prim B-type stars in the ScoOB2 association (d≈145 pc), Shatsky & Tokovinin (2002) utilized near-infrared adaptive optics to search for visual companions across ρ=0 3-6 4, i.e., a=45-900au. Their sample of B0-B9 stars is weighted toward lower primary masses according to the IMF, and so the average primary mass is á ñ M 1 =5±2 M e .…”

Section: Late B Primariesmentioning

confidence: 99%

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Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

Moe

Stefano

2017

ApJS

1,096

1,200

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We compile observations of early-type binaries identified via spectroscopy, eclipses, long-baseline interferometry, adaptive optics, common proper motion, etc. Each observational technique is sensitive to companions across a narrow parameter space of orbital periods P and mass ratios q=M comp /M 1 . After combining the samples from the various surveys and correcting for their respective selection effects, we find that the properties of companions to O-type and B-type main-sequence (MS) stars differ among three regimes. First, at short orbital periods P20days (separations a0.4 au), the binaries have small eccentricities e0.4, favor modest mass ratios á ñ » q 0.5, and exhibit a small excess of twins q>0.95. Second, the companion frequency peaks at intermediate periods log P (days)≈3.5 (a ≈ 10 au), where the binaries have mass ratios weighted toward small values q≈0.2-0.3 and follow a Maxwellian "thermal" eccentricity distribution. Finally, companions with long orbital periods log P (days)≈5.5-7.5 (a ≈ 200-5000 au) are outer tertiary components in hierarchical triples and have a mass ratio distribution across q≈0.1-1.0 that is nearly consistent with random pairings drawn from the initial mass function. We discuss these companion distributions and properties in the context of binary-star formation and evolution. We also reanalyze the binary statistics of solar-type MS primaries, taking into account that 30% ±10% of single-lined spectroscopic binaries likely contain white dwarf companions instead of low-mass stellar secondaries. The mean frequency of stellar companions with q>0.1 and log P (days)<8.0 per primary increases from 0.50±0.04 for solar-type MS primaries to 2.1±0.3 for O-type MS primaries. We fit joint probability density functions ¹ ( ) ( ) ( ) ( ) ( ) f M q P e f M f q f P f e , , , 1 1 to the corrected distributions, which can be incorporated into binary population synthesis studies.

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Section: Definitionsmentioning

confidence: 99%

Section: Visual Binariesmentioning

confidence: 99%

Section: Late B Primariesmentioning

confidence: 99%

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Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

Moe

Stefano

2017

ApJS

1,096

1,200

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“…The distribution function of mass ratios is generally described as a power law ( f (μ) ∝ μ γ ), but the value of γ is still much debated in the literature (Duquennoy & Mayor 1991;Shatsky & Tokovinin 2002;Kouwenhoven et al 2005) and therefore we will take it as a free parameter 1 . Figure 6 shows the evolution with time of the type Ia SN rate for different models and different SFRs, analogously to Fig.…”

Section: Type Ia Sn Ratesmentioning

confidence: 99%

The chemical evolution of galaxies within the IGIMF theory: the [α/Fe] ratios and downsizing

Recchi

Calura²,

Kroupa³

2009

A&A

106

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Context. The chemical evolution of galaxies is investigated within the framework of the star formation rate (SFR) dependent integrated galactic initial mass function (IGIMF). Aims. We study how the global chemical evolution of a galaxy and in particular how [α/Fe] abundance ratios are affected by the predicted steepening of the IGIMF with decreasing SFR. Methods. We use analytical and semi-analytical calculations to evaluate the mass-weighted and luminosity-weighted [α/Fe] ratios in early-type galaxies of different masses.Results. The models with variable IGIMF produce an [α/Fe] vs. velocity dispersion relation which has the same slope as the observations of massive galaxies, irrespective of the model parameters, provided that the star formation duration inversely correlates with the mass of the galaxy (downsizing). These models also produce steeper [α/Fe] vs. σ relations in low-mass early-type galaxies and this trend is consistent with the observations. Constant IMF models are able to reproduce the [α/Fe] ratios in large elliptical galaxies as well, but they do not predict this change of slope for small galaxies. In order to obtain the best fit between our results and observations, the downsizing effect (i.e. the shorter duration of the star formation in larger galaxies) must be milder than previously thought.

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“…Indeed, recent simulations suggest that A stars may possess a greater abundance of both stellar and planetary mass companions (Kratter et al 2010, J. Crepp 2010. However, the multiplicity characteristics of these more massive stars have only recently started to be surveyed (Shatsky & Tokovinin 2002;Kouwenhoven et al 17 Sagan Fellow. 18 NSF Postdoctoral Fellow. 2005), and more extensive surveys are underway to place limits on the nature of massive-star multiplicity.…”

Section: Introductionmentioning

confidence: 99%

ESTABLISHING α Oph AS A PROTOTYPE ROTATOR: IMPROVED ASTROMETRIC ORBIT

Hinkley

Monnier

Oppenheimer

et al. 2010

ApJ

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The nearby star α Oph (Ras Alhague) is a rapidly rotating A5IV star spinning at ∼ 89% of its breakup velocity. This system has been imaged extensively by interferometric techniques, giving a precise geometric model of the star's oblateness and the resulting temperature variation on the stellar surface. Fortuitously, α Oph has a previously known stellar companion, and characterization of the orbit provides an independent, dynamically based check of both the host star and the companion mass. Such measurements are crucial to constrain models of such rapidly rotating stars. In this study, we combine eight years of adaptive optics imaging data from the Palomar, AEOS, and CFHT telescopes to derive an improved, astrometric characterization of the companion orbit. We also use photometry from these observations to derive a model-based estimate of the companion mass. A fit was performed on the photocenter motion of this system to extract a component mass ratio. We find masses of 2.40 +0.23 −0.37 M and 0.85 +0.06 −0.04 M for α Oph A and α Oph B, respectively. Previous orbital studies of this system found a mass too high for this system, inconsistent with stellar evolutionary calculations. Our measurements of the host star mass are more consistent with these evolutionary calculations, but with slightly higher uncertainties. In addition to the dynamically derived masses, we use IJHK photometry to derive a model-based mass for α Oph B, of 0.77 ± 0.05 M marginally consistent with the dynamical masses derived from our orbit. Our model fits predict a periastron passage on 2012 April 19, with the two components having a 50 mas separation from 2012 March to May. A modest amount of interferometric and radial velocity data during this period could provide a mass determination of this star at the few percent level.

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The mass ratio distribution of B-type visual binaries in the Sco OB2 association

Cited by 149 publications

References 28 publications

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

Mind Your Ps and Qs: The Interrelation between Period (P) and Mass-ratio (Q) Distributions of Binary Stars

The chemical evolution of galaxies within the IGIMF theory: the [α/Fe] ratios and downsizing

ESTABLISHING α Oph AS A PROTOTYPE ROTATOR: IMPROVED ASTROMETRIC ORBIT

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