Visual Binary Research Articles

Spin–Orbit Alignment of Early-type Astrometric Binaries and the Origin of Slow Rotators

The spin–orbit alignment of binary stars traces their formation and accretion history. Previous studies of spin–orbit alignment have been limited to small samples, slowly rotating solar-type stars, and/or wide visual binaries that not surprisingly manifest random spin–orbit orientations. We analyze 917 Gaia astrometric binaries across periods P = 100–3000 days (a = 0.5–5 au) that have B8-F1 IV/V primaries (M 1 = 1.5–3 M ⊙) and measured projected rotational velocities v sin i. The primary stars in face-on orbits exhibit substantially smaller v sin i compared to those in edge-on orbits at the 6σ level, demonstrating significant spin–orbit alignment. The primaries in our astrometric binaries are rotating more slowly than their single-star or wide-binary counterparts and therefore comprise the slow-rotator population in the observed bimodal rotational velocity distribution of early-type stars. We discuss formation models of close binaries where some of the disk angular momentum is transferred to the orbit and/or secondary spin, quenching angular momentum flow to the primary spin. The primaries in astrometric binaries with small mass ratios q = M 2/M 1 < 0.3 possess even smaller v sin i, consistent with model predictions. Meanwhile, astrometric binaries with large eccentricities e > 0.4 do not display spin–orbit alignment or spin reduction. Using a Monte Carlo technique, we measure a spin–orbit alignment fraction of F align = 75% ± 5% and an average spin reduction factor of 〈S align〉 = 0.43 ± 0.04. We conclude that 75% of close A-type binaries likely experienced circumbinary disk accretion and probably formed via disk fragmentation and inward disk migration. The remaining 25%, mostly those with e > 0.4, likely formed via core fragmentation and orbital decay via dynamical friction.

Astrometric Binary Classification via Artificial Neural Networks

With nearly two billion stars observed and their corresponding astrometric parameters evaluated in the recent Gaia mission, the number of astrometric binary candidates has risen significantly. Due to the surplus of astrometric data, the current computational methods employed to inspect these astrometric binary candidates are both computationally expensive and cannot be executed in a reasonable time frame. In light of this, a machine learning (ML) technique to automatically classify whether a set of stars belongs to an astrometric binary pair via an artificial neural network (ANN) is proposed. Using data from Gaia Data Release 3, the ANN was trained and tested on 1.5 million highly probable true and visual binaries, considering the proper motions, parallaxes, and angular and physical separations as features. The ANN achieves high classification scores, with an accuracy of 99.3%, a precision rate of 0.988, a recall rate of 0.991, and an area under the curve of 0.999, indicating that the utilized ML technique is a highly effective method for classifying astrometric binaries. Thus, the proposed ANN is a promising alternative to the existing methods for the classification of astrometric binaries.

Detecting New Visual Binaries in Gaia DR3 with Gaia and Two Micron All Sky Survey (2MASS) Photometry. II. Speckle Observations of 16 Low-separation Systems

Here we present speckle observations of 16 low-separation (s < 30 au) high-probability candidate binaries from the catalog by Medan et al., where secondaries typically lack astrometric solutions in Gaia. From these speckle observations, we find a second component is always detected within the field of view. To determine if the detection is consistent with a physical companion or a chance alignment with a background source, we utilize a statistic from Tokovinin & Kiyaeva that compares the apparent motion of the systems to the expected orbital motion ( μ′ ). Using simulated binary orbits, we construct likelihood distributions of μ′ assuming various total errors on the measurements. With the hypothesis that the system is a true binary, we show that large measurement errors can result in μ′ values higher than expected for bound systems. Using simulated chance alignments, we also create similar likelihoods to test this alternative hypothesis. By combining likelihoods of both true binaries and chance alignments, we find that 15 of the 16 candidates are physical systems regardless of the level of measurement error. Our findings also accommodate all 16 as physical systems if the average, relative measurement error on the binary separations and position angles is ∼4.3%, which is consistent with our knowledge of the Gaia and Gemini speckle pipelines. Importantly, beyond assessing the likelihood of a true binary versus chance alignment, this quantitative assessment of the true average measurement error will allow more robust error estimates of mass determinations from short separation binaries with Gaia and/or Gemini speckle data.

Forty Hypervelocity Stars from Gaia DR3

Forty hypervelocity stars (HVS) are detected from a search for HVS in Gaia DR3 data whose G magnitudes are less than 17.0 and radial velocities are more +400 km s−1. The Gaia DR3 astrophysical parameters and spectra indicate that most of the HVS reported in this study are F, G, and K type metal-poor stars. Eleven stars are at high galactic latitudes. Included in this study are the B components of six nearby visual double stars BD-6 885B, HD 47503B, HD 53229B, HD 95123B, HD 180683B, and HD 202276B which are found to be HVS. The A components of these six visual doubles are less massive late-type stars with normal radial velocities. The source of hypervelocity of the B components is not clear. They may have less luminous and relatively massive degenerate component stars which are not yet detected. Further study of all these HVS is needed.

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2016–2017

AbstractWe present relative astrometric and photometric measurements of visual double stars made in 2016–2017, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry and the direct vector autocorrelation (DVA) method. From our observations of 1,510 multiple stars, we obtained 2,918 new measurements with angular separations in the range 0″.1–20″ and an average accuracy of . The mean error on the position angles is 1°.1. Most of the position angles were determined without the usual 180° ambiguity with the application of the DVA technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems () with large magnitude differences (up to ). We have thus been able to measure six systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 593 double stars with a mean error of 0.1 mag. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 46 measurements with an angular separation smaller than the diffraction limit of our instrumentation. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. We also report the measurements of 205 new double stars that we found in the files obtained during the observations.

The RMS survey: A census of massive YSO multiplicity in the K band

ABSTRACT Close to 100 per cent of massive stars are thought to be in binary systems. The multiplicity of massive stars seems to be intrinsically linked to their formation and evolution, and massive young stellar objects (MYSOs) are key in observing this early stage of star formation. We have surveyed three samples totalling hundreds of MYSOs ($\gt 8\, \mathrm{M}_\odot$) across the Galaxy from the Red MSX Source (RMS) catalogue, using United Kingdom Infra-Red Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) and Vista Variables in the Via Lactea (VVV) point source data, and UKIRT K-band imaging to probe separations between 0.8 and 9 arcsec (approx 1000–100 000 au). We have used statistical methods to determine the binary statistics of the samples, and we find binary fractions of 64 ± 4 per cent for the UKIDSS sample, 53 ± 4 per cent for the VVV sample, and 49 ± 8 per cent for the RMS imaging sample. Also, we use the J- and K-band magnitudes as a proxy for the companion mass, and a significant fraction of the detected systems have estimated mass ratios &amp;gt;0.5, suggesting a deviation from the capture formation scenario which would be aligned with random IMF sampling. Finally, we find that YSOs located in the outer Galaxy have a higher binary fraction than those in the inner Galaxy. This is likely due to a lower stellar background density than observed towards the inner Galaxy, resulting in higher probabilities for visual binaries to be physical companions. It does indicate a binary fraction in the probed separation range of close to 100 per cent without the need to consider selection biases.

Detecting New Visual Binaries in Gaia DR3 with Gaia and Two Micron All Sky Survey (2MASS) Photometry. I. New Candidate Binaries within 200 pc of the Sun

We present a method to identify likely visual binaries in Gaia eDR3 that does not rely on parallax or proper motion. This method utilizes the various point-spread function sizes of Two Micron All Sky Survey (2MASS)/Gaia, where at <2.″5 two stars may be unresolved in 2MASS but resolved by Gaia. Due to this, if close neighbors listed in Gaia are a resolved pair, the associated 2MASS source will have a predictable excess in the J band that depends on the ΔG of the pair. We demonstrate that the expected relationship between 2MASS excess and ΔG differs for chance alignments, as compared to true binary systems, when parameters like magnitude and location on the sky are also considered. Using these multidimensional distributions, we compute the likelihood of a close pair of stars to be a chance alignment, resulting in a total(clean) catalog of 68,725(50,230) likely binaries within 200 pc with a completeness rate of ∼75%(∼64%) and contamination rate of ∼14%(∼0.4%). Within this, we find 590 previously unidentified binaries from Gaia eDR3 with projected physical separations <30 au, where 138 systems were previously identified, and for s < 10 au we find that 4 out of 15 new likely binaries have not yet been observed with high-resolution imaging. We also demonstrate the potential of our catalog to determine physical separation distributions and binary fraction estimates, from this increase in low-separation binaries. Overall, this catalog provides a good complement for the study of local binary populations by probing smaller physical separations and mass ratios, and provides prime targets for speckle monitoring.

The 24 Aqr triple system: A closer look at its unique high-eccentricity hierarchical architecture

As its periastron passage occurred during the third quarter of 2020, system 24 Aqr is of particular significance. New visual solutions for the latest speckle interferometry observations collected by the Lowell Discovery Telescope (LTD) with its new QWSSI speckle camera are presented here. A variety of techniques were used to analyze the system, including ORBITX code for orbital solution, Al-Wardat’s method for analyzing multiple stellar systems, and Edwards’ method for analyzing visual and spectroscopic binaries. We derive precise masses and the complete set of its fundamental parameters for the three components, and we introduce a new orbital solution, and a new dynamical parallax, which is very close to the measured value given by Hipparcos 2007 and from that of Gaia DR2. In the next section, we discuss the possibility of a coplanar orbit. In conclusion, we demonstrate that we need a 65-m telescope to resolve the inner binary visually, although an array of telescopes could be used instead.

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014 (new data) and in 2015

AbstractWe present relative astrometric and photometric measurements of visual double stars made in 2013–2015, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. Most of the observations were done in 2015, but some other observations of wide couples were done in 2013–2014 (0.3% of the total of the observations). Three different techniques were used for obtaining measurements: lucky imaging, speckle interferometry and the direct vector autocorrelation method. From our observations of 2837 multiple stars, we obtained 5182 new measurements with angular separations in the range of 0.1–32 and an average accuracy of . The mean error on the position angles is 0°.8. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems () with large magnitude difference (up to ). We have thus been able to measure 21 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 1079 double stars with an estimated error of 0.2 mag. Except for a few objects that are discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 196 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. We also report measurements of the 164 new double stars that we found in the files obtained during the observations. Finally, from a study of the DR3 Gaia release, it is shown that all the objects of the Tycho Double Star Catalog that we did not resolve in 2015 are probably false detections by Tycho.

Erratum to “Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014”

Erratum to “Measurements of visual double stars with <scp>PISCO2</scp> at the Nice 76‐cm refractor in 2013–2014”

A low-mass companion desert among intermediate-mass visual binaries: The scaled-up counterpart to the brown dwarf desert

ABSTRACT We present a high-contrast imaging survey of intermediate-mass (1.75–4.5 M⊙) stars to search the most extreme stellar binaries, i.e. for the lowest mass stellar companions. Using adaptive optics at the Lick and Gemini observatories, we observed 169 stars and detected 24 candidates companions, 16 of which are newly discovered, and all but three are likely or confirmed physical companions. Despite obtaining sensitivity down to the substellar limit for 75 per cent of our sample, we do not detect any companion below 0.3 M⊙, strongly suggesting that the distribution of stellar companions is truncated at a mass ratio of qmin ≳ 0.075. Combining our results with known brown dwarf companions, we identify a low-mass companion desert to intermediate-mass stars in the range 0.02 ≲ q ≲ 0.05, which quantitatively matches the known brown dwarf desert among solar-type stars. We conclude that the formation mechanism for multiple systems operates in a largely scale-invariant manner and precludes the formation of extremely uneven systems, likely because the components of a protobinary accrete most of their mass after the initial cloud fragmentation. Similarly, the mechanism to form ‘planetary’ (q ≲ 0.02) companions likely scales linearly with stellar mass, probably as a result of the correlation between the masses of stars and their protoplanetary discs. Finally, we predict the existence of a sizable population of brown dwarf companions to low-mass stars and of a rising population of planetary-mass objects towards ${\approx}1\,M_\mathrm{Jup}$ around solar-type stars. Improvements on current instrumentation will test these predictions.

Орбиты визуально-двойных и кратных звезд, полученные методом параметров видимого движения в течение последних 40 лет

Summed many years of work at Pulkovo, the orbits of 67 wide pairs of visual double and multiple stars (included in 64 systems) which were obtained by the Apparent Motion Parameters (AMP) method are presented. This short arc orbit determination method uses the most reliable astrometric and astrophysical data corresponding to one instant of time. The rest of the observations accumulated in the world serve to control the quality of the orbit and refine some parameters. All early determined AMP-orbits were compared with new observations, part of them recalculated, new orbits added. For the stars of Pulkovo program of observations with a 26-inch refractor, the data from the Gaia DR2 catalog were analised. The orbits of 16 stars were calculated on these data. The direction of the motion derived from Gaia DR2 at the instant 2015.5 contradicts to the series of all observations for 20 stars. The probable reason is in the presence of inner subsystems. The orientation of the obtained orbits in the Galaxy frame is also given.

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014

AbstractWe present relative astrometric and photometric measurements of visual double stars made in 2013–2014 with PISCO2 installed at the 76‐cm refractor of the Côte d'Azur Observatory in Nice (France). Our observation list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry, and the Direct Vector Autocorrelation method. From our observations of 4,864 multiple stars, we obtained 4,952 new measurements with angular separations in the range 0″.1–14″ and an average accuracy of 0″.015. The mean error on the position angles is 1°.0. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV ≈ 9–11) with large magnitude differences (up to ΔmV ≈ 5). We have thus been able to measure 49 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 318 double stars with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 455 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. Finally, we report 378 measurements of the 296 new double stars that we found in the files obtained during the observations.

Wide binary stars with non-coeval components

Abstract We have the estimated masses of components of visual binaries from their spectral classification. We have selected pairs in which the less massive component looks more evolved. Spectral observations of some of these pairs were made, and at least one pair, HD 156331, was confirmed to have components of different ages. Since mass exchange is excluded in wide binaries, it means that HD 156331 can be formed by capture.

Yet another star in the Albireo system

Context. Albireo is a well-known bright visual double star. It is still unclear if the components A and B form a gravitationally bound system. The component Albireo A is itself a binary star. The orbital parameters of the Albireo Aa, Ac system have been determined only recently. Thus, Albireo is still of interest for current research. Aims. We aim to present evidence for the detection of a new member in the Albireo system. Furthermore, we aim to determine the orbital parameters and to find further conclusions for the Albireo system. Methods. We used spectroscopic observations of Albireo A obtained with the TIGRE telescope and determined the radial velocities during a period of over three years. We analyzed the radial velocity curve with RadVel to determine the orbital parameters. In addition, we determined the stellar parameters of Albireo Aa with iSpec. Results. We found clear evidence for yet another star in the Albireo system orbiting Albireo Aa with a period of about P = 371 days. Several alternative explanations for the periodic radial velocity signal could be discarded. The new companion Albireo Ad is a low mass star of about 0.085 M⊙. Conclusions. We conclude that Albireo is a hierarchical multiple star system and remains an interesting object for future observations and studies.

Surveying the Bright Stars by Optical Interferometry. III. A Magnitude-limited Multiplicity Survey of Classical Be Stars

Abstract We present the results of a multiplicity survey for a magnitude-limited sample of 31 classical Be stars conducted with the Navy Precision Optical Interferometer and the Mark III Stellar Interferometer. The interferometric observations were used to detect companions in 10 previously known binary systems. For two of these sources (66 Oph and β Cep) new orbital solutions were obtained, while for a third source (υ Sgr) our observations provide the first direct, visual detection of the hot companion to the primary star. Combining our interferometric observations with an extensive literature search, we conclude that an additional four sources (o Cas, 15 Mon, β Lyr, and β Cep) also contain wider binary components that are physical companions to the narrow binaries, thus forming hierarchical multiple systems. Among the sources not previously confirmed as spectroscopic or visual binaries, BK Cam was resolved on a number of nights within a close physical proximity of another star with relative motion possibly suggesting a physical binary. Combining our interferometric observations with an extensive literature search, we provide a detailed listing of companions known around each star in the sample, and discuss the multiplicity frequency in the sample. We also discuss the prospects for future multiplicity studies of classical Be stars by long-baseline optical interferometry.

20 Orbits of binaries based on soar speckle observations

ABSTRACT New observational data obtained during the 2018, 2019, and 2020 speckle runs with the 4.1-m Southern Astrophysical Research (SOAR) telescope located at Cerro Pachón (Chile) allowed us to recalculate the orbits of the visual binaries: WDS 00277-1625 (YR 1 Aa,Ab), WDS 00462-2214 (RST4155), WDS 03124-4425 (JC 8), WDS 07427-3510 (HDS 1091), WDS 10093+2020 (A2145), WDS 10116+1321 (HU 874 AB), WDS 10217-0946 (BU 25), WDS 11585-2350 (RST 3767 AB), WDS 13117-2633 (FIN 305), WDS 13305+0729 (A 1789), and WDS 16458-0046 (A1141). In addition, we present the first orbits calculated for the following binaries: WDS 07303-5657 (FIN 105), WDS 09110-1929 (I 824), WDS 12111-5302 (HU 1604), WDS 14592-4206 (HDS 2116 Aa,Ab), WDS 15157-2736 (BU 350), WDS 15493+0503 (A 1126), WDS 16402-2800 (VOU 44 AB), and WDS 18126+1224 (HDS 2570). All of them are placed below Dec. + 21° and the majority are main-sequence stars. Except in cases with giant components or close triple systems, the ANAPAR method was used in order to obtain precise dynamical parallaxes and individual masses. These parallaxes were compared with those obtained by Gaia and/or Hipparcos satellites. In the case of FIN 305, we present two different orbital solutions. Also, using the dynamical parallaxes given by these orbits, we have been able to calculate the luminosity of these systems. Said luminosities allow us to indicate an approximate age for the components of these systems, situating them within the Hertzsprung-Russell (HR) diagram. In addition, a commentary for each binary about the physical and dynamical properties of the studied binaries has been included.

Measurements of visual binaries with PISCO2 at the Nice 76‐cm refractor in 2011–2012

AbstractWe present relative astrometric and photometric measurements of visual binaries made in 2011–2012, with PISCO2 installed at the 76‐cm refractor of Côte d'Azur Observatory in Nice (France). Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques have been used for obtaining those measurements: Lucky imaging, speckle interferometry, and the direct vector autocorrelation method. From our observations of 3,136 multiple stars, we obtained 3,568 new measurements with angular separations in the range of 0″.1–10″ and an average accuracy of 0″.016. The mean error on the position angles is 1°.7. Most of the position angles were determined without the usual 180° ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the Lucky images or the long integration files. We managed to routinely monitor faint systems (mV ≈ 9–11) with large magnitude difference (up to ΔmV ≈ 5). We have thus been able to measure many systems containing red dwarf stars that had been poorly monitored since their discovery. We also measured the magnitude difference of the two components of 326 binaries with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in a good agreement with the ephemerides computed with published orbital elements, even for the binaries closer than the diffraction limit. Thanks to good seeing images and with the use of high‐contrast numerical filters, we have also been able to obtain 196 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. We also obtained new measurements of the 15th magnitude multiple system CON37, and discovered a faint new double star in its vicinity. Finally, we report 47 measurements of 28 new binaries found during our observations.

Speckle Interferometry at the OAN-SPM México: Multiband Astrometry of Double Stars Measured in 2018 and 2019

Abstract In this paper we present multiband speckle interferometric measurements of double stars performed at the 2.1 m telescope of the Observatorio Astronómico Nacional, San Pedro Mártir, México. We focused our efforts on objects from the Washington Double Star Catalog that were observed during five runs allocated in 2018 and 2019. We report here 2101 astrometric and 2027 photometric measurements of 631 pairs, with angular separations ranging from 0.″05 to 6.″09, including 1622 measurements with separations smaller than 1″, and a magnitude difference up to 5.99 mag through the V filter, 5.46 mag for the R filter, and 5.85 mag for the I filter. We estimated a mean error in separation of 12 mas, 1.°1 in position angle, and 0.14 mag for the magnitude difference. We confirmed 58 double stars discovered by Hipparcos. For the first time we are presenting astrometric measurements for 7 systems listed at the Washington Double Star Catalog as being suspected binaries, which did not have a secondary confirmation, and 15 stars with only one published measurement. We identified a new close companion with a mean angular separation of 0.″10, detected in a previously known pair. Finally, we present a correction to two previously published orbital solutions of two visual binaries.

The Census of Exoplanets in Visual Binaries: Population Trends from a Volume-Limited Gaia DR2 and Literature Search

We present results from an extensive search in the literature and Gaia DR2 for visual co-moving binary companions to stars hosting exoplanets and brown dwarfs within 200 pc. We found 218 planet hosts out of the 938 in our sample to be part of multiple-star systems, with 10 newly discovered binaries and 2 new tertiary stellar components. This represents an overall raw multiplicity rate of 23.2 ± 1.6 % for hosts to exoplanets across all spectral types, with multi-planet systems found to have a lower stellar duplicity frequency at the 2.2-σ level. We found that more massive hosts are more often in binary configurations, and that planet-bearing stars in multiple systems are predominantly observed to be the most massive component of stellar binaries. Investigations of the multiplicity of planetary systems as a function of planet mass and separation revealed that giant planets with masses above 0.1 MJup are more frequently seen in stellar binaries than small sub-Jovian planets with a 3.6-σ difference, a trend enhanced for the most massive (&amp;gt;7 MJup) short-period (&amp;lt;0.5 AU) planets and brown dwarf companions. Binarity was however found to have no significant effect on the demographics of low- mass planets (&amp;lt;0.1 MJup) or warm and cool gas giants (&amp;gt;0.5 AU). While stellar companion mass appears to have no impact on planet properties, binary separation seems to be an important factor in the resulting structure of planetary systems. Stellar companions on separations &amp;lt;1000 AU can play a role in the formation or evolution of massive, close-in planets, while planets in wider binaries show similar properties to planets orbiting single stars. Finally, our analyses indicate that numerous stellar companions on separations smaller than 1–3 arcsec likely remain undiscovered to this date. Continuous efforts to complete our knowledge of stellar multiplicity on separations of tens to hundreds of AU are essential to confirm the reported trends and further our understanding of the roles played by multiplicity on exoplanets.