Spectrographic Observations of Visual Double Stars.

Struve, Otto; Franklin, K. L.

doi:10.1086/145993

Cited by 8 publications

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“…He concluded that Equ itself is a much more compact binary. (It is perhaps interesting to note that the Struve family's study of the system continued through 1955, when O. Struve and K. L. Franklin [Struve & Franklin 1955] included the system in a spectroscopic study.) Delta Equ (7 Equ, HR 8123, HIP 104858, HD 202275, ADS 14773) is among the most well-studied nearby binary star systems.…”

Section: Introductionmentioning

confidence: 99%

PHASES High-Precision Differential Astrometry of δ Equulei

et al. 2005

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Delta Equulei is among the most well-studied nearby binary star systems. Results of its observation have been applied to a wide range of fundamental studies of binary systems and stellar astrophysics. It is widely used to calibrate and constrain theoretical models of the physics of stars. We report 27 high-precision differential astrometry measurements of Equ from the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES). The median size of the minor axes of the uncertainty ellipses for these measurements is 26 as. These data are combined with previously published radial velocity data and other previously published differential astrometry measurements using other techniques to produce a combined model for the system orbit. The distance to the system is determined to within one twentieth of a parsec, and the component masses are determined at the level of a percent. The constraints on masses and distance are limited by the precisions of the radial velocity data; we outline plans to improve this deficiency and discuss the outlook for further study of this binary.

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Section: Introductionmentioning

confidence: 99%

PHASES High-Precision Differential Astrometry of δ Equulei

et al. 2005

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“…15232+3017 (STF 1937 AB). Components of η CrB have been classified G2 V + G2 V (Struve & Franklin 1955), but later Bidelman (1985) estimated a system spectral type F9 V. Our dynamical parallax (56.02 ± 0.03 mas) is in perfect agreement with the trigonometric value of HIP2 (Gaia not available), 55.98 ± 0.78 mas, as well as with individual masses for a G0 V + G2 V system (1.081 ± 0.001 M and 1.023 ± 0.001 M ).…”

Section: Comments On the Individual Systemsmentioning

confidence: 99%

Colour-dependent accurate modelling of dynamical parallaxes and masses of visual binaries

Andrade

2019

A&A

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Context. Two fundamental characteristics of binary systems are the masses of their components and their distance to the Earth. In this way, the dynamical parallax is an accurate and very helpful tool. Nevertheless, there has been some concern with regard to the use of a unique linear mass–luminosity relation (MLR) for the entire main sequence (MS). Aims. This article describes the accurate computation of both dynamical parallaxes and individual masses of visual binaries. The main aim is to formulate a model which would be suitable for binary systems attending to the exact locations of the components on the MS in the HR diagram. Methods. An analytical model was developed which allows calculation of dynamical parallaxes and individual masses using a non-linear MLR valid for the entire MS. This up-to-date MLR is given by a polynomial of degree 20. In contrast to previous approaches, this model can be applied even in the case of components with unequal masses, that is, with an arbitrarily large difference of magnitudes between them. On the other hand, considering the fundamental equation of the theory that forms the basis of the model, we propose to estimate uncertainties in parallax and masses using Monte Carlo simulations. Results. The model was validated by means of numerical tests using a synthetic sample comprising 103 systems. The results are much more accurate than those for previous models reported in the literature for deriving dynamical parallaxes and masses. Furthermore, we present dynamical parallaxes and individual masses for the 19 double-lined spectro-interferometric systems with definitive visual orbits and compare the former with the orbital parallaxes as well as with those measured by HIPPARCOS and Gaia. It is worth mentioning that the latter can only be a reliable source when the orbital motion is taken into account. Thus, at present, many Gaia DR2 parallaxes of binaries are biased. Conclusions. Our model, composed of an exact analytical theory, along with a non-linear MLR, guarantees high accuracy even in cases where the components are of unequal mass.

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Rotation in Close Binaries (Review Paper)

Plavec

1970

Stellar Rotation

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Spectrographic Observations of Visual Double Stars.

Cited by 8 publications

References 0 publications

PHASES High-Precision Differential Astrometry of δ Equulei

PHASES High-Precision Differential Astrometry of δ Equulei

Colour-dependent accurate modelling of dynamical parallaxes and masses of visual binaries

Rotation in Close Binaries (Review Paper)

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