The mass-ratio distribution of Visual Binary Stars

Hogeveen, Sake J.

doi:10.1007/bf00643940

Cited by 16 publications

(17 citation statements)

References 10 publications

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“…However, more results have been published favoring other f (q)'s. Hogeveen (1990Hogeveen ( , 1992a finds that f (q) can be a power law, either decreasing or increasing, depending on whether the sample (from Batten et al 1978 Eighth Catalogue of Spectroscopic Binaries -SB) was formed by single-line (SBI) or double-line (SBII) systems. This calls attention to the extent to which selection effects can influence results.…”

Section: Introductionmentioning

confidence: 99%

The mass ratio and initial mass functions in spectroscopic binaries

Ducati

Penteado

Turcati

2010

A&A

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Context. Spectroscopic binaries are important in studies of binary star-formation, since original information linked to the forming stars, such as the mass ratio, can be kept in the system and observationally retrieved. Aims. We aim to derive the more probable mass ratio distributions, to test a possible Initial Mass Functions acting on the formation of spectroscopic binaries, and to derive the value of q 0 , the minimal mass ratio for which both binary components are simultaneously in the main sequence. Methods. The sample has 249 systems, selected from the Ninth Catalogue of Spectroscopic Binaries, with selection criteria that include only those systems with periods longer than four days and magnitudes brighter than m V = 7.0, and main-sequence primaries, to avoid mass exchange. Monte Carlo simulations of observational parameters were performed. We performed simulations by comparing an observational quantity, Y obs , equal to f (m)/m 1 , where f (m) is the mass function, to theoretical Y th , which is a function of the system inclination (assumed to be random), and of the mass ratio q = m 2 /m 1 . We considered a minimal mass ratio q 0 , which is the limiting condition, to ensure that both components are simultaneously on main sequence, avoiding evolutionary effects leading to mass exchange and loss of information on the original masses. Calculations were done using several q 0 values. The form of the distribution of mass ratios was studied by simulations of Y, involving several functions, with slopes which are increasing, decreasing, constant, or bimodal. Other simulations were done by the generation of stars following several initial mass function laws. We combined pairs of stars generated from different IMFs, assuming that binaries arise from the pairing of stars simultaneously formed. In this case, several values of q 0 were also used in the input equations. Results. Our results indicate that decreasing q distributions match better with observations and also that a unique IMF gives better fits to observations than a composite IMF, with a slope around 1.4, rather than the widely used 2.35 slope. Values of q 0 tend to be lower than what is suggested by previous studies, which point to q 0 around 0.2; all simulations suggest that q 0 values as low as 0.08 produce the best fits to observations.

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Section: Introductionmentioning

confidence: 99%

The mass ratio and initial mass functions in spectroscopic binaries

Ducati

Penteado

Turcati

2010

A&A

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“…by Hogeveen (1990). In the present section, I try to show that implausibly large bias effects in the data are needed in order to produce the observed peak.…”

Section: Possible Systematic Errorsmentioning

confidence: 93%

“…by Hogeveen (1990), there is a particularly heavy bias towards equal-magnitude systems in the Fourth Catalog of Orbits of Visual Binary Stars (Worley & Heintz 1983), which was the last available in the preparation of the Hipparcos Input Catalog. Many of the binaries in that catalog were high-priority objects for parallax determination by Hipparcos, and it is conceivable that this has produced a peaked selection, with small-∆m systems more likely to be included.…”

Section: Possible Systematic Errorsmentioning

confidence: 99%

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Theq= 1 peak in the mass-ratios for Hipparcos visual binaries

Söderhjelm

2006

A&A

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Aims. The magnitude differences for Hipparcos visual binaries give important information about the upper part of their mass-ratio distribution, and in previous studies, the author found a narrow peak at q = 1 This excess of equal-mass, wide pairs has not been confirmed in other studies, and the present work aims to strengthen the Hipparcos results. Methods. We construct a Galaxy model with binaries of known properties, filter it through a "Hipparcos-like" selection model, and then compare the model with the actual Hipparcos observations. By changing the input distributions in the model, the fit to the observations can be improved, enabling some conclusions about the mass-ratio distribution f q (q) and the distribution of semi-major axes f a (a). The most important weak point is the modelling of the selection effects in the Hipparcos Input Catalog, but by testing different biases, typical effects can be quantified. Results. From fittings in different color(mass)-intervals, I find that the shapes of the distributions of orbit-sizes and mass-ratios vary with mass, even in the small (1.9−5.5 Msun) mass-sum interval well covered by the Hipparcos data. In particular, the excess of "twins" in f q (q) is definitely present, but the peak amplitude diminishes at higher masses. There is normally also a decrease in the number of binaries with increasing mass-ratio in the interval 0.5 < q < 0.9, but below 2 Msun, this slope suddenly reverses, giving a broad peak towards 1.0 below the narrow one. For typical wide orbits (100−1000 au), the f a (a)-distribution shows a steeper decline for lower masses, while almost reaching the scale-free 1/a power-law for the highest ones.

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“…It appears likely, from the work of Garmany et al (1980) that the mass-ratio distribution of O-type binaries can be reasonably well approximated by a flat distribution, whereas the works of Abt & Levy (1978) and Trimble (1990) yield distributions qS(q) ranging from approximately fiat to qS(q) ~ q-1 (Trimble). Hogeveen (1991) even obtained a distribution as steep as ~b(q) ,,~ q-2 down to q = 0.3 to 0.4 and fiat below q = 0.3.…”

Section: Statistical Properties Of Unevolved Ob-binai~iesmentioning

confidence: 94%

Massive Close Binaries: Observational Characteristics

Heuvel

1994

Evolution of Massive Stars

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Abstract. Theoretically predicted evolutionary phases of massive close binaries are compared with the observations. For the evolution up to the High-Mass X-ray Binary (HMXB) phase there is fair agreement between theory and observation. Beyond the HMXB phase there is much uncertainty. Notably it is puzzling why we observe so few systems consisting of a helium star and a neutron star (Cygnus X-3 is the only one found so far), and why the incidence of double neutron stars is so low. A better understanding of Common Envelope evolution is required in order to answer these questions. The role of velocity kicks imparted to neutron stars during supernova collapse is discussed. Such kicks might cause many runaway OB stars to be single.

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The mass-ratio distribution of Visual Binary Stars

Cited by 16 publications

References 10 publications

The mass ratio and initial mass functions in spectroscopic binaries

The mass ratio and initial mass functions in spectroscopic binaries

Theq= 1 peak in the mass-ratios for Hipparcos visual binaries

Massive Close Binaries: Observational Characteristics

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