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 Search for (sub)stellar Companions of Exoplanet Hosts by Exploring the Second ESA-Gaia Data Release

2021 ◽  
Vol 8 ◽  
Author(s):  
K.-U. Michel ◽  
M. Mugrauer
Keyword(s):  
White Dwarf ◽  
Proper Motion ◽  
Brown Dwarfs ◽  
The Sun ◽  
Data Release ◽  
Gravitational Stability ◽  
Using Data ◽  
Triple Star ◽  
Gaia Dr2

We present the latest results of an ongoing multiplicity survey of exoplanet hosts, which was initiated at the Astrophysical Institute and University Observatory Jena, using data from the second data release of the ESA-Gaia mission. In this study the multiplicity of 289 targets was investigated, all located within a distance of about 500 pc from the Sun. In total, 41 binary, and five hierarchical triple star systems with exoplanets were detected in the course of this project, yielding a multiplicity rate of the exoplanet hosts of about 16%. A total of 61 companions (47 stars, a white dwarf, and 13 brown dwarfs) were detected around the targets, whose equidistance and common proper motion with the exoplanet hosts were proven with their precise Gaia DR2 astrometry, which also agrees with the gravitational stability of most of these systems. The detected companions exhibit masses from about 0.016 up to 1.66 M⊙ and projected separations in the range between about 52 and 9,555 au.

scholarly journals Binary Star Population with Common Proper Motion in Gaia DR2

2020 ◽  
Vol 64 (9) ◽  
pp. 756-768
Author(s):  
S. A. Sapozhnikov ◽  
D. A. Kovaleva ◽  
O. Yu. Malkov ◽  
A. Yu. Sytov
Keyword(s):  
Proper Motion ◽  
Binary Star ◽  
Gaia Dr2

scholarly journals The distribution of relative proper motions of wide binaries in GAIA DR2: MOND or multiplicity?

2019 ◽  
Author(s):  
C J Clarke
Keyword(s):  
Proper Motion ◽  
Weak Field ◽  
Close Binary ◽  
Newtonian Gravity ◽  
Proper Motions ◽  
General Shape ◽  
Field Limit ◽  
Wide Binary ◽  
Weak Field Limit ◽  
Gaia Dr2

Abstract We examine the distribution of on-sky relative velocities for wide binaries previously assembled from GAIA DR2 data and focus on the origin of the high velocity tail of apparently unbound systems which may be interpreted as evidence for non-Newtonian gravity in the weak field limit. We argue that this tail is instead explicable in terms of a population of hidden triples, i.e. cases where one of the components of the wide binary is itself a close binary unresolved in the GAIA data. In this case the motion of the photocentre of the inner pair relative to its barycentre affects the apparent relative proper motion of the wide pair and can make pairs that are in fact bound appear to be unbound. We show that the general shape of the observed distributions can be reproduced using simple observationally motivated assumptions about the population of hidden triples.

Mass Ratios in Wide Binary Stars

1997 ◽  
Vol 485 (2) ◽  
pp. 785-788 ◽  
Author(s):  
Mauri J. Valtonen
Keyword(s):  
Binary Stars ◽  
Wide Binary ◽  
Mass Ratios

A pas de trois birth for wide binary stars

Nature ◽  
2012 ◽  
Vol 492 (7428) ◽  
pp. 191-192
Author(s):  
Keivan Guadalupe Stassun
Keyword(s):  
Binary Stars ◽  
Wide Binary

scholarly journals Gaia DR2 reveals a very massive runaway star ejected from R136

2018 ◽  
Vol 619 ◽  
pp. A78 ◽  
Author(s):  
D. J. Lennon ◽  
C. J. Evans ◽  
R. P. van der Marel ◽  
J. Anderson ◽  
I. Platais ◽  
...  
Keyword(s):  
Lower Limit ◽  
Proper Motion ◽  
Evolutionary History ◽  
Massive Star ◽  
Position Angle ◽  
Proper Motions ◽  
Central Cluster ◽  
Dynamical Constraints ◽  
Runaway Stars ◽  
Gaia Dr2

A previous spectroscopic study identified the very massive O2 III star VFTS 16 in the Tarantula Nebula as a runaway star based on its peculiar line-of-sight velocity. We use the Gaia DR2 catalog to measure the relative proper motion of VFTS 16 and nearby bright stars to test if this star might have been ejected from the central cluster, R136, via dynamical ejection. We find that the position angle and magnitude of the relative proper motion (0.338±0.046 mas yr−1, or approximately 80±11 km s−1) of VFTS 16 are consistent with ejection from R136 approximately 1.5±0.2 Myr ago, very soon after the cluster was formed. There is some tension with the presumed age of VFTS 16 that, from published stellar parameters, cannot be greater than 0.9+0.3−0.2 Myr. Older ages for this star would appear to be prohibited due to the absence of He I lines in its optical spectrum, since this sets a firm lower limit on its effective temperature. The dynamical constraints may imply an unusual evolutionary history for this object, perhaps indicating it is a merger product. Gaia DR2 also confirms that another very massive star in the Tarantula Nebula, VFTS 72 (alias BI 253; O2 III-V(n)((f*)), is also a runaway on the basis of its proper motion as measured by Gaia. While its tangential proper motion (0.392±0.062 mas yr−1 or 93±15 km s−1) would be consistent with dynamical ejection from R136 approximately 1 Myr ago, its position angle is discrepant with this direction at the 2σ level. From their Gaia DR2 proper motions we conclude that the two ∼100 M⊙ O2 stars, VFTS 16 and VFTS 72, are fast runaway stars, with space velocities of around 100 km s−1 relative to R136 and the local massive star population. The dynamics of VFTS 16 are consistent with it having been ejected from R136, and this star therefore sets a robust lower limit on the age of the central cluster of ∼1.3 Myr.

scholarly journals Dynamical Study of the Exoplanet Host Binary System HD 106515

2017 ◽  
Vol 34 ◽  
Author(s):  
F. M. Rica ◽  
R. Barrena ◽  
J. A. Henríquez ◽  
F. M. Pérez ◽  
P. Vargas
Keyword(s):  
Radial Velocity ◽  
Proper Motion ◽  
Binary Star ◽  
Semimajor Axis ◽  
Numerical Code ◽  
Dynamical Study ◽  
Orbital Parameters ◽  
Instantaneous Position ◽  
Dynamical Parameters ◽  
Binary Star System

AbstractHD 106515 AB (STF1619 AB) is a high common proper motion and common radial velocity binary star system composed of two G-type bright stars located at 35 pc and separated by about 7 arcsec. This system was observed by theHipparcossatellite with a precision in distance and proper motion of 3 and 2%, respectively. The system includes a circumprimary planet of nearly 10 Jupiter masses and a semimajor axis of 4.59 AU, discovered using the radial velocity method. The observational arc of 21° shows a small curvature that evidences HD 106515 AB is a gravitationally bound system. This work determines the dynamical parameters for this system which reinforce the bound status of both stellar components. We determine orbital solutions from instantaneous position and velocity vectors. In addition, we provide a very preliminary orbital solution and a distribution of the orbital parameters, obtained from the line of sight (z). Our results show that HD 106515 AB presents an orbital period of about 4 800 years, a semimajor axis of 345 AU and an eccentricity of about 0.42. Finally, we use an N-body numerical code to perform simulations and reproduce the longer term octupole perturbations on the inner orbit.

scholarly journals New star clusters discovered towards the Galactic bulge direction using Gaia DR2

2021 ◽  
Vol 502 (1) ◽  
pp. L90-L94
Author(s):  
F A Ferreira ◽  
W J B Corradi ◽  
F F S Maia ◽  
M S Angelo ◽  
J F C Santos
Keyword(s):  
Spatial Distribution ◽  
Star Clusters ◽  
Open Clusters ◽  
Systematic Search ◽  
Joint Analysis ◽  
The Sun ◽  
Galactic Bulge ◽  
Gaia Dr2

ABSTRACT We report the discovery of 34 new open clusters and candidates as a result of a systematic search carried out in 200 adjacent fields of 1 × 1 deg2 area projected towards the Galactic bulge, using Gaia DR2 data. The objects were identified and characterized by a joint analysis of their photometric, kinematic, and spatial distribution that has been consistently used and proved to be effective in our previous works. The discoveries were validated by cross-referencing the objects position and astrometric parameters with the available literature. Besides their coordinates and astrometric parameters, we also provide sizes, ages, distances, and reddening for the discovered objects. In particular, 32 clusters are closer than 2 kpc from the Sun, which represents an increment of nearly $39{{\ \rm per\ cent}}$ of objects with astrophysical parameters determined in the nearby inner disc. Although these objects fill an important gap in the open clusters distribution along the Sagittarius arm, this arm, traced by known clusters, appears to be interrupted, which may be an artefact due to the incompleteness of the cluster census.

Sign in / Sign up

Export Citation Format

Share Document