Data for Binary Stars from Gaia DR2

2021 ◽  
pp. 125-133
Author(s):  
Dana Kovaleva ◽  
Oleg Malkov ◽  
Sergei Sapozhnikov ◽  
Dmitry Chulkov ◽  
Nikolay Skvortsov
Keyword(s):  
Binary Stars ◽  
Gaia Dr2

scholarly journals Observational signs of wide binary stars dissolution in Gaia DR2 data

2020 ◽  
pp. 336-340
Author(s):  
С.А. Сапожников ◽  
Д.А. Ковалева
Keyword(s):  
Binary Stars ◽  
Proper Motion ◽  
Binary Star ◽  
Logarithmic Scale ◽  
The Sun ◽  
Numerical Estimation ◽  
Wide Binary ◽  
Random Pairing ◽  
The Common ◽  
Gaia Dr2

По данным Gaia DR2 в радиусе 100 пк от Солнца исследованы двойные звезды с общим собственным движением до расстояния между компонентами 3 пк. Для исключения возможных случайных совпадений смоделирована искусственная выборка случайных пар. Показано, что принятый способ отбора пар с общим собственным движением делает загрязнение выборки случайными совпадениями незначительным даже при больших расстояниях между компонентами; величина такого загрязнения оценена численно. Получено бимодальное распределение по логарифму расстояния между компонентами, демонстрирующее для очень широких пар минимум, связанный с распадом систем, на расстоянии ≈ 0.5 пк, и дальнейший рост, формируемый распавшимися, медленно расходящимися компонентами. Binary and common proper motion stars within 100 pc of the Sun are being investigated using Gaia DR2 data. An artificial random pairs sample is constructed to exclude possible random pairing contamination. Numerical estimation of this contamination shows that the chosen method to select the common proper motion stars yields little contamination even at high separations. In a logarithmic scale the separation distribution appear to have a minimum at ≈ 0.5 pc, most likely related to binary star dissolution, with further increase formed by dissolved, slowly distancing components.

scholarly journals Testing modified gravity with wide binaries in Gaia DR2

2019 ◽  
Vol 488 (4) ◽  
pp. 4740-4752 ◽  
Author(s):  
Charalambos Pittordis ◽  
Will Sutherland
Keyword(s):  
Dark Matter ◽  
Binary Stars ◽  
Modified Gravity ◽  
Simulated Data ◽  
Peak Shift ◽  
Wide Binary ◽  
A Value ◽  
Modified Gravity Theories ◽  
Clear Peak ◽  
Gaia Dr2

ABSTRACT Several recent studies have shown that very wide binary stars can potentially provide an interesting test for modified-gravity theories which attempt to emulate dark matter; these systems should be almost Newtonian according to standard dark-matter theories, while the predictions for MOND-like theories are distinctly different, if the various observational issues can be overcome. Here we explore an observational application of the test from the recent Gaia DR2 data release: we select a large sample of ∼24 000 candidate wide binary stars with distance $\lt 200 \, {\rm pc}$ and magnitudes G < 16 from Gaia DR2, and estimated component masses using a main-sequence mass–luminosity relation. We then compare the frequency distribution of pairwise relative projected velocity (relative to circular-orbit value) as a function of projected separation; these distributions show a clear peak at a value close to Newtonian expectations, along with a long ‘tail’ which extends to much larger velocity ratios; the ‘tail’ is considerably more numerous than in control samples constructed from DR2 with randomized positions, so its origin is unclear. Comparing the velocity histograms with simulated data, we conclude that MOND-like theories without an external field effect (ExFE) are strongly inconsistent with the observed data since they predict a peak-shift in clear disagreement with the data; testing MOND-like theories with an ExFE is not decisive at present, but has good prospects to become decisive in future with improved modelling or understanding of the high-velocity tail, and additional spectroscopic data.

scholarly journals Mining of the Milky Way Star Archive Gaia-DR2. Searching for Binary Stars in Planetary Nebulae

Proceedings ◽  
2020 ◽  
Vol 54 (1) ◽  
pp. 52
Author(s):  
Iker González-Santamaría ◽  
Minia Manteiga ◽  
Carlos Dafonte ◽  
Arturo Manchado ◽  
Ana Ulla
Keyword(s):  
Binary Stars ◽  
Binary Systems ◽  
Planetary Nebulae ◽  
Central Star ◽  
Separation Distance ◽  
Proper Motions ◽  
Use Of Data ◽  
Stellar Sources ◽  
Stellar Envelopes ◽  
Gaia Dr2

The aim of this work is to search for binary stars associated to planetary nebulae (ionized stellar envelopes in expansion), by mining the astronomical archive of Gaia DR2, that is composed by around 1.7 billion stellar sources. For this task, we selected those objects with coincident astrometric parameters (parallaxes and proper motions) with the corresponding central star, among a sample of 211 planetary nebulae. By this method, we found eight binary systems, and we obtained their components positions, separations, temperatures and luminosities, as well as some of their masses and ages. In addition, we estimated the probability for each companion star of having been detected by chance and we analyzed how the number of false matches increase as the separation distance between both stars gets larger. All these procedures have been carried out making use of data mining techniques.

scholarly journals Comparison of Gaia and Hipparcos parallaxes of close visual binary stars and the impact on determinations of their masses

2021 ◽  
Vol 38 ◽  
Author(s):  
Mashhoor Ahmad Al-Wardat ◽  
Abdallah M. Hussein ◽  
Hamid M. Al-Naimiy ◽  
Martin A. Barstow
Keyword(s):  
Binary Stars ◽  
Precise Measurement ◽  
Stellar Systems ◽  
Dramatic Improvement ◽  
Fundamental Parameters ◽  
Visual Binary ◽  
Visual Binary Stars ◽  
The Impact ◽  
Gaia Dr2 ◽  
Visual Binaries

Abstract Precise measurement of the fundamental parameters of stellar systems, including mass and radius, depends critically on how well the stellar distances are known. Astrometry from space provides parallax measurements of unprecented accuracy, from which distances can be derived, initially from the Hipparcos mission, with a further refinement of that analysis provided by van Leeuwen in 2007. The publication of the Gaia DR2 catalogue promises a dramatic improvement in the available data. We have recalculated the dynamical masses of a sample of 1 700 close visual binary stars using Gaia DR2 and compared the results with masses derived from both the original and enhanced Hipparcos data. We show the van Leeuwen analysis yields results close to those of Gaia DR2, but the latter are significantly more accurate. We consider the impact of the Gaia DR2 parallaxes on our understanding of the sample of visual binaries.

RSCVn Stars in the Southern Hemisphere

1979 ◽  
Vol 46 ◽  
pp. 371-384 ◽  
Author(s):  
J.B. Hearnshaw
Keyword(s):  
Light Curve ◽  
Southern Hemisphere ◽  
Orbital Period ◽  
Binary Stars ◽  
Small Amplitude ◽  
Light Variation ◽  
Orbital Phase

RSCVn stars are fully detached binary stars which show intrinsic small amplitude (up to 0.3 amplitude peak-to-peak) light variations, as well as, in most of the known cases, eclipses. The spectra are F to G, IV to V for the hotter component and usually KOIV for the cooler. They are also characterised by abnormally strong H and K emission from the cooler star, or, occasionally, from both components. The orbital and light curve periods are in the range 1 day to 2 weeks. An interesting feature is the migration of the light variations to earlier orbital phase, as the light variation period is shorter than the orbital period by a few parts in 10+4to a few parts in 10+3.

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