Photocentric orbits from a direct combination 
 of ground-based astrometry with Hipparcos

Gontcharov, G. A.; Kiyaeva, O. V.

doi:10.1051/0004-6361:20020896

Cited by 14 publications

(12 citation statements)

References 21 publications

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“…As mentioned before, Judge et al concluded that a main sequence companion would have to be a star later than G-type. A K-dwarf has a mass of between 0.6-0.8 M ; taking values of 1.1 -1.2M for δ And A gives 0.3-0.4 as the mass fraction, reasonably consistent with the value of Gontcharov & Kiyaeva (2002) of 0.5 ± 0.1. However, there are some discrepancies.…”

Section: Results and Conclusionsupporting

confidence: 60%

Resolving the Delta Andromedae Spectroscopic Binary With Direct Imaging

Bottom

Kühn

Mennesson

et al. 2015

ApJ

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We present a direct image of the innermost companion to the red giant δ Andromedae using the Stellar Double Coronagraph at the Palomar Observatory. We use a Markovchain Monte Carlo based algorithm to simultaneously reduce the data and perform astrometry and photometry of the companion. We determine that the companion is most likely a main-sequence K-type star and is certainly not the previously hypothesized white dwarf.

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Section: Results and Conclusionsupporting

confidence: 60%

Resolving the Delta Andromedae Spectroscopic Binary With Direct Imaging

Bottom

Kühn

Mennesson

et al. 2015

ApJ

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“…02225-2349 = κ For is a bright star with invisible component. Gontcharov & Kiyaeva (2002) proposed an astrometric orbit with a period 26.5 yr and semi-major axis α = 0. 26 ± 0.…”

Section: Discussion Of Individual Systemsmentioning

confidence: 99%

First Speckle Interferometry at SOAR Telescope with Electron-Multiplication CCD

Tokovinin¹,

Cantarutti²

2008

PUBL ASTRON SOC PAC

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A simple camera with electron-multiplication CCD, fast frame rate, and pixel scale of 15 mas is described. This instrument was tested at the SOAR 4-m telescope in speckle interferometry regime. The data were processed by the standard speckle algorithm permitting to derive binary-star parameters. We observed 29 objects with separations from 21 mas to 1. 32, mostly southern binaries with known orbits. Some pairs require orbit revision. Two spectroscopic binaries HIP 9631 and HIP 11072 and the astrometric binary κ For are resolved for the first time, three objects were unresolved.

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“…For many it should be possible to determine a photocentre orbit with semi-major axis a photo (Gontcharov & Kiyaeva 2002;Sahlmann et al 2015):…”

Section: Unresolved Binaries With Gaiamentioning

confidence: 99%

The binarity of the local white dwarf population

Toonen

Hollands

Gänsicke

et al. 2017

A&A

182

194

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Context. As endpoints of stellar evolution, white dwarfs (WDs) are powerful tools to study the evolutionary history of the Galaxy. In particular, the multiplicity of WDs contains information regarding the formation and evolution of binary systems. Aims. Can we understand the multiplicity of the local WD sample from a theoretical point of view? Population synthesis methods are often applied to estimate stellar space densities and event rates, but how well are these estimates calibrated? This can be tested by a comparison with the 20 pc sample, which contains ≃ 100 stars and is minimally affected by selection biases. Methods. We model the formation and evolution of single stars and binaries within 20 pc with a population synthesis approach. We construct a model of the current sample of WDs and differentiate between WDs in different configurations, that is single WDs, and resolved and unresolved binaries containing a WD with either a main-sequence (MS) component or with a second WD. We also study the effect of different assumptions concerning the star formation history, binary evolution, and the initial distributions of binary parameters. We compile from the literature the available information on the sample of WDs within 20 pc, with a particular emphasis on their multiplicity, and compare this to the synthetic models. Results. The observed space densities of single and binary WDs are well reproduced by the models. The space densities of the most common WD systems (single WDs and unresolved WD-MS binaries) are consistent within a factor two with the observed value. We find a discrepancy only for the space density of resolved double WDs. We exclude that observational selection effects, fast stellar winds, or dynamical interactions with other objects in the Milky Way explain this discrepancy. We find that either the initial mass ratio distribution in the Solar neighbourhood is biased towards low mass-ratios, or more than ten resolved DWDs have been missed observationally in the 20 pc sample. Furthermore, we show that the low binary fraction of WD systems (∼25%) compared to Solartype MS-MS binaries (∼50%) is consistent with theory, and is mainly caused by mergers in binary systems, and to a lesser degree by WDs hiding in the glare of their companion stars. Lastly, Gaia will dramatically increase the size of the volume-limited WD sample, detecting the coolest and oldest WDs out to ≃ 50 pc. We provide a detailed estimate of the number of single and binary WDs in the Gaia sample.

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Photocentric orbits from a direct combination of ground-based astrometry with Hipparcos

Cited by 14 publications

References 21 publications

Resolving the Delta Andromedae Spectroscopic Binary With Direct Imaging

Resolving the Delta Andromedae Spectroscopic Binary With Direct Imaging

First Speckle Interferometry at SOAR Telescope with Electron-Multiplication CCD

The binarity of the local white dwarf population

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