Search for (sub)stellar companions of exoplanet hosts by exploring the second ESA-Gaia data release
rreceived: 01 Nov 2020; accepted: 25 Jan 2021
Search for (sub)stellar companions ofexoplanet hosts by exploring the secondESA-Gaia data release
K.-U. Michel , ∗ & M. Mugrauer Astrophysikalisches Institut und Universit ¨ats-Sternwarte Jena, Schillerg ¨aßchen 2,D-07745 Jena, Germany
Correspondence*:Corresponding Author: K.-U. [email protected]
ABSTRACT
We present the latest results of an ongoing multiplicity survey of exoplanet hosts, which wasinitiated at the Astrophysical Institute and University Observatory Jena, using data from thesecond data release of the ESA-Gaia mission. In this study the multiplicity of 289 targets wasinvestigated, all located within a distance of about 500 pc from the Sun. In total, 41 binary, and5 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 (47stars, a white dwarf, and 13 brown dwarfs) were detected around the targets, whose equidistanceand common proper motion with the exoplanet hosts were proven with their precise Gaia DR2astrometry, which also agrees with the gravitational stability of most of these systems. Thedetected companions exhibit masses from about 0.016 up to 1.66 M (cid:12) and projected separationsin the range between about 52 and 9555 au.
Keywords: Multiple Stars, White Dwarfs, Brown Dwarfs, Exoplanets, ESA-Gaia DR2
Since the detection of the first planet orbiting a star other than the Sun, several thousands of these exoplanetshave been discovered by various detection techniques. While the majority of stars are members of multiplestar systems (Duchˆene and Kraus, 2013), most of the exoplanet host stars are single stars. Neverthelessseveral multiple star systems hosting exoplanets, could already be revealed by previous multiplicity studiesusing seeing limited or high contrast AO imaging observations (see e.g. Mugrauer et al., 2014; Mugrauer andGinski, 2015). In order to explore the effects of the presence of stellar companions on the formation processand orbital evolution of exoplanets, a survey was initiated at the Astrophysical Institute and UniversityObservatory Jena (described in detail by Mugrauer, 2019) to identify and characterize companions ofexoplanet host stars, detected in the second data release of the European Space Agency (ESA) Gaia mission(Gaia DR2 from hereon, Gaia Collaboration et al., 2018). Furthermore, in Mugrauer and Michel (2020)a comparable investigation was carried out among potential exoplanet host stars, identified by the TESSmission (Ricker et al., 2015). The study, whose results are presented here, is the third work in the contextwith Mugrauer (2019). The following section gives a detailed description of this study, and the detectedcompanions and their derived properties are presented in the third section of this paper. a r X i v : . [ a s t r o - ph . E P ] F e b ichel & Mugrauer Stellar companions of exoplanet hosts
The Gaia DR2, is based on data taken by the Gaia spacecraft in the first 22 months of its mission andcontains . billion detected sources up to a limiting magnitude of G = 21 mag. For 1.3 billion sources afive parameter astrometric solution could be derived, i.e. beside their equatorial coordinates ( α , δ ), also theparallax π and proper motion ( µ α cos ( δ ) , µ δ ) of these sources were determined. Furthermore, for about 88million detected objects estimates of their G-band extinction and effective temperature are listed in theGaia DR2, determined by the Priam algorithm, which is part of the astrophysical parameters inferencesystem (Apsis, see Bailer-Jones et al., 2013) in the Gaia data processing.Using Gaia DR2 data Mugrauer (2019) already explored the multiplicity of all exoplanet host stars, whoseexoplanets were detected either by photometric transit observations, radial-velocity (RV), or astrometricmeasurements, and were listed in the Extrasolar Planets Encyclopaedia ( EPE from hereon,Schneider et al., 2011) by mid of October 2018. The study, presented in this paper, complements this surveyby investigating the multiplicity of the exoplanet hosts (stars but also brown dwarfs), whose planets wereindirectly detected either via RV measurements or transit observations in the range of time between midof October 2018 until end of September 2020, as well as all exoplanet hosts, known so far, with planets,which were directly detected by imaging observations. At the end of September 2020 the
EPE lists about4350 exoplanets, and about 400 of them were detected around the hosts studied in this work.(Sub)stellar Companions are expected to be located at the same distance to the Sun as the exoplanet hostsand form common proper motion pairs with them, in particular wide companions with projected separationsof hundreds and thousands of au, i.e. the typical targets of this study. Hence, in order to clearly detect suchcompanions and to prove the equidistance of these objects and the exoplanet hosts, in this study we havetaken into account only Gaia DR2 sources with an accurate five parameter astrometric solution, i.e. whichexhibit precise measurements of their parallax ( π/σ ( π ) > ) and proper motion ( µ/σ ( µ ) > ). Thereby,sources with negative parallaxes are neglected. As in the Gaia DR2 a parallax uncertainty of 0.7 mas isreached for faint sources down to G = 20 mag, the survey is furthermore constrained to exoplanet hosts,which are located within a distance of 500 pc around the Sun (i.e. π > mas), to assure π/σ ( π ) > even for the faintest companions, detectable in this survey. This distance constraint is slightly relaxedto π + 3 σ ( π ) (cid:39) mas, i.e. taking into account also the parallax uncertainty of the hosts. By the end ofSeptember 2020, in total 289 exoplanet hosts are listed in the EPE , which fulfill this distance constraint, andhence are selected as targets for this study. The properties of all targets are summarized in Tab. 1 and theirhistograms are illustrated in Fig. 1. On average, the targets are solar like stars most frequently found within150 pc around the Sun, which exhibit proper motions in the range between about 2 and 10400 mas/yr, andG-band magnitudes from about 3.7 to 20.8 mag. In particular, the sub-sample of direct imaging exoplanethosts emerges as a peak in the age distribution at young ages, as all these targets are typically younger than0.1 Gyr, in contrast to hosts of RV and transiting exoplanets, which are older than 1 Gyr in general.The companion search radius, applied in this project around the selected targets, is limited to a maximalprojected separation of 10000 au, which guarantees that the majority of wide companions of the exoplanethosts are detectable in this study, as described by Mugrauer (2019). This upper separation limit results inan angular search radius around the targets of r [ arcsec ] = 10 π [ mas ] . Within this radius around the targetsthe companionship of all sources, listed in the Gaia DR2 with an accurate five parameter astrometricsolution was investigated. For the verification of the equidistance of all detected sources with the associated Online available at: http://exoplanet.eu/ ichel & Mugrauer Stellar companions of exoplanet hosts exoplanet hosts, the difference ∆ π between their parallaxes was calculated, taking into account also theexcess noise of their astrometric solutions. Common proper motion of the detected sources and the targetswas checked with the precise Gaia DR2 proper motions of the exoplanet hosts µ P H and the sources µ Comp .In addition, we have also derived for all sources the differential proper motion: µ rel = | µ P H − µ Comp | ,which yields the common proper motion index (cpm-index = | µ P H + µ Comp | /µ rel ), which characterizesthe degree of common proper motion of the detected sources and the exoplanet hosts.Following the companion identification procedure ( sig - ∆ π ≤ & cpm-index ≥ ), as defined byMugrauer (2019) the majority of all sources ( > ρ , and position angle P A ), as well as their projected separation sep , derived with their angularseparation and the parallax of the targets.The absolute G-band magnitude of all companions was derived from their apparent G-band photometry,the parallax of the associated exoplanet hosts, as well as their Apsis-Priam G-band extinction estimate,all listed in the Gaia DR2. If there was no extinction estimate given for a companion, the extinctionestimate of the exoplanet host was used instead or if not available, its extinction estimate, listed in the
StarHorse catalog (Anders et al., 2019). In the case that no G-band extinction is available at all it wasderived from V-band extinction measurements of the exoplanet hosts, listed either in the
VizieR database (Ochsenbein et al., 2000) or in the literature, adopting A G /A V = 0 . , as described by Mugrauer(2019).The masses and effective temperatures of all detected companions were determined from their derivedabsolute G-band magnitudes using the evolutionary models of (sub)stellar objects from Baraffe et al.(2015), as well as the ages of the exoplanet hosts, as listed in the EPE . Thereby, we adopt the same agefor the planet hosts and their companions. We determined the masses and effective temperatures of thecompanions via interpolation of the model grid with the age closest to that of the exoplanet hosts. Forverification of the obtained results the properties of the companions derived from their G-band magnitudeswere compared with those, determined from the near-infrared photometry, taken from the 2MASS PointSource catalogue (Skrutskie et al., 2006), if available. For the near-infrared extinction we have used therelations: A Ks /A V = 0 . , A H /A V = 0 . , and A J /A V = 0 . , as described in Mugrauer (2019). Agraphical comparison of the masses obtained from the G-band and the 2MASS photometry are shown inFig. 2. The identity is illustrated as grey dashed line in this figure. For all companions the derived massesagree well with each other, with deviations that remain below the σ level (the same holds also for thetemperature estimates not shown here). Objects, whose masses were determined by extrapolation fromthe used model grids as such as those with bad quality (quality flags all but A) or contaminated 2MASSphotometry were excluded in this comparison.Eventually for all companions, which were detected in this study, we have estimated their escape velocity µ esc [ mas yr − ] = 2 π (cid:113) M π P H /ρ with their angular separation ρ and the parallax of the associatedexoplanet hosts both in the unit of milli-arcsec (mas), as well as the total mass M of the system (in the unit M (cid:12) ), i.e. the sum of the mass of the companions, derived as describe above, and the mass of the associated Online available at: https://vizier.u-strasbg.fr/ ichel & Mugrauer Stellar companions of exoplanet hosts exoplanet hosts, taken from the
EPE . This estimation can be considered as an upper limit of the escapevelocity as the projected separation is smaller than the physical separation of the objects.
The Gaia astro- and photometry of all exoplanet hosts and their companions, detected in this study, arelisted in Tab. 2. The derived properties of the companions are summarized in Tab. 3 to 5. In all tables theexoplanet host systems or the companions are sorted by their right ascension. The used identifier of thetargets corresponds either to the one used in the
EPE or is a slightly abbreviated version of it. In contrast tothe planet definition used by the
EPE , in which substellar objects below 60 M Jup are defined as exoplanets,we follow here the planet definition based on the deuterium burning limit (as described e.g. by Basri, 2000),i.e. all substellar objects below 13 M Jup are classified as exoplanets, while more massive objects belowthe substellar/stellar mass limit (at about 0.072 M Jup for solar metallicity) as brown dwarfs, respectively.Thereby the given masses of the exoplanets, detected by radial velocity measurements, correspond tominimum-masses ( M sin( i ) ) due to the unknown orbital inclination, while masses of direct imaging planetsare usually derived from their spectrophotometry with evolutionary models.In Tab. 2 for each exoplanet host and its detected co-moving companion(s) their Gaia DR2 parallax π ,proper motion in right ascension and declination ( µ α cos( δ ) & µ δ ), astrometric excess noise (epsi) with itssignificance (sig-epsi), apparent G-band magnitude, as well as the used Apsis-Priam G-band extinctionestimate A G are listed. In the case that the G-band extinction was taken from the StarHorse catalogthis is indicated with the
SHC flag, or with the (cid:122) flag if the G-band extinction was derived from V-bandextinction measurements, either listed in the
VizieR database or from the literature. In this table theexoplanet hosts are indicated with * , and known spectroscopic binary stars among them with (SB) .Table 3 lists for each detected companion its angular separation ( ρ ) and position angle ( P A ) to theassociated exoplanet host, which were determined with the Gaia DR2 astrometry of the objects for the(Gaia reference) epoch 2015.5. The relative astrometry of the companions exhibits an uncertainty onaverage of 0.3 mas in angular separation, and 0.002 ◦ in position angle, respectively. In the followingcolumns of Tab. 3 we list the parallax difference ( ∆ π ) with its significance (in brackets calculated bytaking into account also the Gaia astrometric excess noise ) between the exoplanet hosts and their detectedcompanions, their differential proper potion µ rel with its significance, and the cpm-index of all systems.The precise Gaia DR2 astrometry proves the equidistance (sig- ∆ π < . σ , average value of . σ ) andcommon proper motion (cpm-index > , average cpm-index = 118 ) of the exoplanet hosts and theircompanions. If these companions are not listed yet as companion(-candidates) in the Washington DoubleStar Catalog (WDS from hereon, Mason et al., 2001) this is indicated with the (cid:70) flag in last columnof Tab. 3. In the case that the companion is not listed in the WDS but was reported in literature before,additional information is given in the notes of this table.In Tab. 4 beside the equatorial coordinates ( α , δ both for epoch 2015.5) of all detected companions, theirderived absolute G-band magnitude M G , projected separation sep to the associated exoplanet host (relativeuncertainty about 1 %, on average), mass, and effective temperature T eff are summarized. The flags listedin the last column of this table are defined as follows: • PRI : An Apsis-Priam temperature estimate is available for the detected companion, which couldbe compared with the effective temperature of the companion, derived from its absolute G-bandphotometry using the Baraffe et al. (2015) models. The astrometric excess noise is conservatively considered here as additional parallax uncertainty of the source. ichel & Mugrauer Stellar companions of exoplanet hosts • : The companion is listed in the 2MASS Point Source catalogue. • BPRP : The G BP − G RP color of the exoplanet host and of the detected companion is listed in theGaia DR2, hence a color comparison was feasible. • EXT : Because of its brightness the companion exceeds the magnitude range of the Baraffe et al. (2015)evolutionary models. Therefore, the properties of the companion were estimated via extrapolationfrom the two brightest sources of the used model isochrone. • WD : The detected companion is a white dwarf. • BD : The detected companion is a brown dwarf.Finally, in Tab. 5 we summarize all those detected companions, whose differential proper motion µ rel significantly exceeds their expected escape velocity µ rel . Companions, which are already known to bemembers of hierarchical triple star systems, are indicated with the flag *** in the last column of this table.Among all 289 targets, whose multiplicity was investigated in the study, whose results are presented inthis paper, 41 binary and 5 hierarchical triple star systems with exoplanets were identified. This yieldsa multiplicity rate of the targets of ± ± %, reported before by Mugrauer (2019). This is as expected, as the sensitivities ofthe two surveys should agree well with each other, as the brightness and mass of their targets match,and the distance of the targets from this survey is on average about 40 % smaller than that of the targetsfrom Mugrauer (2019), resulting in a reduction in the distance modulus of only about 1 mag. In total, 61companions (48 stars and 13 brown dwarfs) could be detected in the Gaia DR2 around the targets. Thedetected substellar companions are all listed as exoplanets in the EPE . The cumulative distribution functionsof the derived properties (projected separation, mass and effective temperature) of theses companions,are illustrated in Fig. 3, 4, and 5. The separation-mass diagram of the companions is shown in Fig. 6. Asdescribed above, the accurate Gaia DR2 astrometry proves the equidistance and common proper motion ofall detected companions with the associated exoplanet hosts, and for the majority of these companions theirdifferential proper motion to the exoplanet hosts is slower than their estimated escape velocity, facts that areexpected for gravitationally bound systems. In contrast, the differential proper motion of the companions,which are listed in Tab. 5, exceeds their estimated escape velocity, possibly indicating a higher degree ofmultiplicity. Indeed, one of these companions (51 Eri BC) is already known to be a close binary itself. Theremaining 2 companions and their primaries are promising targets for follow-up observations to check theirmultiplicity status e.g. with high contrast AO imaging observations.All detected companions exhibit projected separations to the associated exoplanet hosts in the rangebetween 52 and 9555 au (average separation of about 2310 au). The highest companion frequency is foundat projected separations between about 240 and 400 au and half of all companions are located at projectedseparations below about 1240 au. The closest detected companion is K2-288 A, which is separated fromthe exoplanet host stars K2-288 B by 52 au, and it is the only companion identified in this study within aprojected separation of 100 au. The masses of the companions range between 0.016 and 1.66 M (cid:12) (averagemass of 0.36 M (cid:12) ) and companions are found most frequently in the substellar mass regime between 0.016up to 0.033 M (cid:12) , while more massive companions are detected at a lower but constant frequency up toabout 0.7 M (cid:12) , and only about 10 % of all the detected companions exhibit masses larger than 0.7 M (cid:12) .The companions exhibit effective temperatures in the range between about 1850 and 6350 K (average Additional close companions either of the exoplanet hosts or of the companions force these objects on close orbits with high orbital velocities around acommon barycenter that could induce the observed high differential velocities. ichel & Mugrauer Stellar companions of exoplanet hosts temperature of about 3400 K), which corresponds to spectral types of L3 to F6 (M3, on average), accordingto the T eff − SpT relation from (Pecaut and Mamajek, 2013).In general the effective temperature of the detected companions, determined with their derived absoluteG-band magnitude, using the evolutionary Baraffe et al. (2015) models, agree well with their Gaia DR2Apsis-Priam temperature estimate (if available) with a characteristic deviation of about ±
350 K, consistentwith the typical uncertainty of the different temperature estimates, which is in the order of about 330 K.Only in the case of HIP 38594 B the temperature estimate, based on the absolute G-band photometry of thecompanion significantly deviates by more than 2300 K from its Apsis-Priam temperature estimate, which isalso about 900 K higher than the one of the associated exoplanet host star HIP 38594 A. Furthermore, thecompanion appears bluer ( ∆( G BP − G RP ) = − . ± . mag) than its primary although it is about7 mag fainter in the G-band than the exoplanet host star. The intrinsic faintness and high temperature ofHIP 38594 B clearly indicates that this companion is a white dwarf. This conclusion is consistent with theresults of Subasavage et al. (2008), who have already classified the companion spectroscopically as a whitedwarf, and have denote it as WD 0751-252. For this degenerated companion we adopt here a mass of about0.6 M (cid:12) .In Fig. 7 the G-band magnitude difference of all detected companions to the associated exoplanet hosts isplotted versus their angular separation. For comparison we show as dashed line in this figure the estimateof the Gaia detection limit, reported by Mugrauer (2019) which was further constrained by Mugrauer andMichel (2020). Companions of exoplanet hosts brighter than 12.8 mag are plotted as open circles thoseof hosts, which are fainter than that magnitude limit, as filled black circles, respectively. A magnitudedifference of about 5 mag is reached at an angular separation of about 2 arcsec, consistent with the estimateof the Gaia detection limit, determined by Mugrauer (2019). Only two companions significantly exceedthe limit estimate, namely K2-288 A at an angular separation of about 0.8 arcsec with ∆ G ∼ . mag andHIP 77900 B, at 22.3 arcsec with ∆ G ∼ . mag. While K2-288 A is a companion of a target fainter than G = 12 . mag for which Gaia reaches a higher sensitivity at angular separations slightly below 1 arcsec(up to 3 mag, as described by Mugrauer and Michel, 2020) the detection of HIP 77900 B indicates that thegiven limit estimate might be too conservative at angular separations beyond about 20 arcsec. The study, presented here, is a continuation of a survey, which was initiated at the Astrophysical Instituteand University Observatory Jena, to investigate the multiplicity status of exoplanet hosts and to characterizethe properties of their detected (sub)stellar companions, using accurate Gaia astro- and photometry. Inthis paper the multiplicity of 289 exoplanet hosts was explored and (sub)stellar companions were detectedaround 60 targets. The companionship of these objects with the exoplanet hosts could be proven withtheir accurate Gaia DR2 astrometry (equidistance, common proper motion, and differential proper motionsmaller than the expected escape velocity). The mass and effective temperature of all companions weredetermined with their derived absolute G-band photometry and the Baraffe et al. (2015) evolutionary modelsof (sub)stellar objects. In total, 61 companions (beside 48 stellar companions, among them the white dwarfHIP 38594 B, also 13 brown dwarfs) were detected in this project, and 14 of these objects are neither listedin the WDS as companion(-candidate)s of the targets nor were described in the literature before. A total of41 binary and 5 triple star systems with exoplanets, were identified in this study, yielding a multiplicity rateof the targets of about 16 %, which is very well consistent with the multiplicity rate of exoplanet host stars,reported by Mugrauer (2019). Following the standard procedure of our survey, all detected companions Online available at: ichel & Mugrauer Stellar companions of exoplanet hosts and their derived properties will be made available online in the
VizieR database. The survey, whoselatest results are presented here, is an ongoing project as more and more exoplanet hosts are detected bydifferent planet detection methods, whose multiplicity status needs to be investigated. Furthermore, thereare sources, listed in the Gaia DR2, within the applied search radius around the targets, which still lack afive parameter astrometric solution. Hence, further companions of the exoplanet hosts, investigated here,should exist, whose companionship can be proven with accurate astrometric measurements, provided byfuture data releases of the ESA-Gaia mission, e.g. the Gaia EDR3, planed to be published end of 2020.The results of this survey, which is mainly sensitive for wide companions of exoplanet hosts, combinedwith those of our currently ongoing large high contrast imaging surveys (sensitive for close companions),carried out with SPHERE/VLT and AstraLux/CAHA (first results are already published e.g. by Ginskiet al., 2020) will yield a complete characterization of the multiplicity status of the observed targets. Thiswill eventually allow to draw conclutions on the impact of the stellar multiplicity on the formation processof planets and the evolution of their orbits.
ACKNOWLEDGMENTS
We thank the two anonymous referees for their helpful and constructive comments on the manuscript.We made use of data from:(1) the
Simbad and
VizieR databases, both operated at CDS in Strasbourg, France.(2) the European Space Agency (ESA) mission Gaia ( ),processed by the Gaia Data Processing and Analysis Consortium (DPAC, ). Funding for the DPAC has been provided by nationalinstitutions, in particular the institutions participating in the Gaia Multilateral Agreement.(3) the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts andthe Infrared Processing and Analysis Center/California Institute of Technology, funded by the NationalAeronautics and Space Administration and the National Science Foundation.
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Table 1.
The properties of all targets of this study. The corresponding histograms are shown in Fig. 1.Distance µ G age mass [ pc ] [ mas/yr ] [ mag ] [ Gyr ] [ M (cid:12) ] min 1.8 1.7 3.7 0.001 0.016max 586 10394 20.8 14.9 20ave 137 270 10.8 3.5 1.1med 94 65 10.7 2.1 1.0 ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . G a i aa s t r o - a ndpho t o m e t r yo f a ll e xop l a n e t ho s t s a nd t h e i r c o m p a n i on s , d e t ec t e d i n t h i ss t udy . N a m e π µ α c o s ( δ ) µ δ e p s i s i g - G A G [ m a s ][ m a s / y r][ m a s / y r][ m a s ] e p s i [ m a g ][ m a g ] HD A * . ± . . ± . − . ± . . . . ± . . + . − . HD C . ± . . ± . − . ± . . . ± . G li e s e A * . ± . . ± . . ± . −− . ± . . + . − . G li e s e B . ± . . ± . . ± . . . ± . HD A * . ± . − . ± . − . ± . −− . ± . HD B . ± . − . ± . − . ± . . . ± . . + . − . HD A * . ± . . ± . − . ± . −− . ± . HD B . ± . . ± . − . ± . . . . ± . . + . − . SHC H R A * . ± . . ± . . ± . . . . ± . . + . − . H R B . ± . . ± . . ± . . . ± . HD A * . ± . . ± . − . ± . −− . ± . HD B . ± . . ± . − . ± . −− . ± . . + . − . K - B * . ± . . ± . − . ± . . . ± . K - A . ± . . ± . − . ± . . . ± . . + . − . SHC HD A * . ± . − . ± . − . ± . −− . ± . . + . − . HD B . ± . − . ± . − . ± . . . . ± . HD B * . ± . − . ± . − . ± . −− . ± . HD A . ± . − . ± . − . ± . −− . ± . . + . − . H II A * ( S B ) . ± . . ± . − . ± . −− . ± . H II C . ± . . ± . − . ± . . . . ± . . + . − . H II D . ± . . ± . − . ± . . . . ± . . + . − . HA T S - A * . ± . − . ± . − . ± . −− . ± . . + . − . HA T S - B . ± . − . ± . − . ± . −− . ± . F U T a u A * . ± . . ± . − . ± . . . ± . . + . − . F U T a u B . ± . . ± . − . ± . . . . ± . DH T a u A * . ± . . ± . − . ± . −− . ± . DH T a u C . ± . . ± . − . ± . −− . ± . . + . − . E r i A * . ± . . ± . − . ± . . . ± . . + . − . E r i B ( S B ) . ± . . ± . − . ± . . . ± . M + C * . ± . . ± . − . ± . . . . ± . M + A B . ± . . ± . − . ± . . . ± . . + . − . ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d N a m e π µ α c o s ( δ ) µ δ e p s i s i g - G A G [ m a s ][ m a s / y r][ m a s / y r][ m a s ] e p s i [ m a g ][ m a g ] NG T S - A * . ± . − . ± . − . ± . −− . ± . NG T S - B . ± . − . ± . − . ± . . . . ± . . + . − . A B D o r A C * . ± . . ± . . ± . . . ± . A B D o r B D . ± . . ± . . ± . . . ± . . + . − . HD A * . ± . . ± . − . ± . −− . ± . HD B . ± . . ± . − . ± . −− . ± . . + . − . NG T S - A * . ± . − . ± . . ± . . . ± . NG T S - B . ± . − . ± . . ± . . . . ± . . + . − . SHC L P up A * . ± . . ± . . ± . −− . ± . HIP L P up B . ± . . ± . . ± . . . ± . . + . − . H I P A * . ± . − . ± . . ± . −− . ± . H I P B . ± . − . ± . . ± . −− . ± . . + . − . W A SP - A * . ± . − . ± . − . ± . −− . ± . W A SP - B . ± . − . ± . − . ± . −− . ± . . + . − . HD B * . ± . − . ± . − . ± . −− . ± . HD A . ± . − . ± . − . ± . −− . ± . . + . − . HD A * . ± . . ± . − . ± . −− . ± . . + . − . HD B . ± . . ± . − . ± . . . ± . T O I A * . ± . − . ± . . ± . . . . ± . . + . − . T O I B . ± . − . ± . . ± . . . . ± . G - A * . ± . − . ± . − . ± . . . . ± . . + . − . G - B . ± . − . ± . − . ± . . . . ± . LTT A * . ± . − . ± . − . ± . . . . ± . . + . − . LTT B . ± . − . ± . − . ± . . . ± . M A S C A R A - A * . ± . − . ± . − . ± . −− . ± . . + . − . M A S C A R A - B . ± . − . ± . − . ± . . . ± . M J - A * . ± . − . ± . . ± . . . ± . M J - B . ± . − . ± . . ± . . . . ± . . + . − . (cid:122) W A SP - A * . ± . − . ± . . ± . −− . ± . W A SP - B . ± . − . ± . . ± . −− . ± . . + . − . ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d N a m e π µ α c o s ( δ ) µ δ e p s i s i g - G A G [ m a s ][ m a s / y r][ m a s / y r][ m a s ] e p s i [ m a g ][ m a g ] C HX R A * . ± . − . ± . . ± . . . ± . . + . − . (cid:122) C HX R C . ± . − . ± . − . ± . . . ± . G J A * . ± . . ± . − . ± . −− . ± . G J B . ± . . ± . − . ± . −− . ± . . + . − . HD A * . ± . − . ± . − . ± . −− . ± . . + . − . HD BC . ± . − . ± . − . ± . . . ± . HD A * . ± . − . ± . . ± . −− . ± . HD B . ± . − . ± . . ± . −− . ± . . + . − . M J - A * . ± . − . ± . − . ± . . . ± . . + . − . (cid:122) M J - B . ± . − . ± . − . ± . . . . ± . NG T S - A * . ± . . ± . − . ± . −− . ± . . + . − . NG T S - B . ± . . ± . − . ± . . . . ± . M J - A * . ± . − . ± . − . ± . . . . ± . . + . − . (cid:122) M J - B . ± . − . ± . − . ± . . . . ± . W A SP - A * . ± . − . ± . − . ± . . . . ± . . + . − . SHC W A SP - B . ± . − . ± . − . ± . . . ± . H I P A * . ± . − . ± . − . ± . −− . ± . H I P D . ± . − . ± . − . ± . . . ± . . + . − . T O I A * . ± . − . ± . − . ± . −− . ± . . + . − . SHC T O I B . ± . − . ± . − . ± . . . ± . M A * . ± . − . ± . − . ± . . . ± . . + . − . SHC M B . ± . − . ± . − . ± . . . . ± . β C i r A * . ± . − . ± . − . ± . . . ± . . + . − . β C i r B . ± . − . ± . − . ± . . . ± . K ELT - A * . ± . . ± . − . ± . −− . ± . . + . − . K ELT - B . ± . . ± . − . ± . . . . ± . K - A * B . ± . . ± . − . ± . −− . ± . . + . − . K - C . ± . . ± . − . ± . . . . ± . GQ L up A * . ± . − . ± . − . ± . . . . ± . . + . − . GQ L up C . ± . − . ± . − . ± . . . ± . ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d N a m e π µ α c o s ( δ ) µ δ e p s i s i g - G A G [ m a s ][ m a s / y r][ m a s / y r][ m a s ] e p s i [ m a g ][ m a g ] H I P A * . ± . − . ± . − . ± . . . ± . . + . − . H I P B . ± . − . ± . − . ± . . . . ± . U S c o1602 - A * . ± . − . ± . − . ± . −− . ± . . + . − . SHC U S c o1602 - B . ± . − . ± . − . ± . . . ± . H I P A ( S B ) * . ± . − . ± . − . ± . . . ± . . + . − . H I P C . ± . − . ± . − . ± . . . ± . U S c o1610 - A * . ± . − . ± . − . ± . . . ± . . + . − . (cid:122) U S c o1610 - B . ± . − . ± . − . ± . . . . ± . U S c o1612 - A * . ± . − . ± . − . ± . . . ± . . + . − . (cid:122) U S c o1612 - B . ± . − . ± . − . ± . . . . ± . R OX s A * . ± . − . ± . − . ± . . . . ± . . + . − . (cid:122) R OX s C . ± . − . ± . − . ± . . . ± . HA T S - A * . ± . . ± . . ± . −− . ± . . + . − . HA T S - B . ± . . ± . . ± . . . . ± . G J A * . ± . − . ± . − . ± . −− . ± . G J B . ± . − . ± . − . ± . . . ± . . + . − . HD A * . ± . − . ± . − . ± . −− . ± . . + . − . HD B . ± . − . ± . − . ± . . . ± . W e nd e l s t e i n - A * . ± . . ± . − . ± . −− . ± . . + . − . W e nd e l s t e i n - B . ± . . ± . − . ± . . . . ± . M J - A * . ± . . ± . − . ± . . . ± . . + . − . SHC M J - B . ± . . ± . − . ± . . . . ± . T O I A * . ± . . ± . − . ± . . . . ± . . + . − . T O I B . ± . . ± . − . ± . . . . ± . NG T S - A * . ± . − . ± . − . ± . . . ± . . + . − . (cid:122) NG T S - B . ± . − . ± . − . ± . . . . ± . D S T u c A * . ± . . ± . − . ± . −− . ± . D S T u c B . ± . . ± . − . ± . −− . ± . . + . − . R X S J + A * . ± . . ± . − . ± . . . . ± . R X S J + C . ± . . ± . − . ± . . . ± . . + . − . ichel & Mugrauer Stellar companions of exoplanet hosts
Comments on individual objects: • HD 1160 A hosts a brown dwarf companion (HD 1160 B, detected by Nielsen et al., 2012), which is listed asexoplanet in the
EPE . • The exoplanet host star
HD 24085 B is the secondary component of a binary system, whose primary starHD 24085 A is also known as HD 24062. • HII 1348 A is a spectroscopic binary with a brown dwarf companion (HII 1348 B, discovered by Geißler et al.,2012), which is listed as exoplanet in the
EPE . • DH Tau A hosts a brown dwarf companion (DH Tau B), which was detected by Itoh et al. (2005) and is listed asexoplanet in the
EPE . DH Tau C (alias DI Tau) is the wide primary component of this system. •
2M 0441+23 C is an exoplanet host brown dwarf (Bowler and Hillenbrand, 2015), which is listed in the
EPE . • The bright AGB star
L2 Pup A is listed in the Gaia DR2 but with a parallax ( π = 7 . ± . mas) thatsignificantly differs from its HIPPARCOS-value ( π = 15 . ± . mas, van Leeuwen, 2007). Furthermore, itshould be noted that the G-band brightness of this star, as listed in the Gaia DR2, is several magnitudes fainterthan expected (e.g. G = 3 . ± . mag, as estimated by Smart and Nicastro, 2014). Therefore, we only usehere the Gaia DR2 equatorial coordinates of this star, while we adopt the HIPPARCOS-values of its parallaxand proper motion, which is indicated with the flag HIP in this table. • HIP 73990 A is the host star of two brown dwarfs (HIP 73990 B & C, revealed by Hinkley et al., 2015), whichare both listed as exoplanets in the
EPE . • GQ Lup A is listed as exoplanet host star in the
EPE , whose substellar companion was detected by Neuh¨auseret al. (2005). The star exhibits a wide stellar companion, whose WDS designation (GQ Lup C) is used here. • HIP 79098 A is a spectroscopic binary and hosts the brown dwarf HIP 79098 B (Janson et al., 2019), which islisted as exoplanet in the
EPE . • ROXs 12 A is the host star of the brown dwarf ROXs 12 B, detected by Kraus et al. (2014), which is listed asexoplanet in the
EPE . • RXSJ2351+3127 A hosts a brown dwarf companion (RXSJ2351+3127 B, discovered by Bowler et al., 2012),which is listed as exoplanet in the
EPE . • HII 1348 A , FU Tau A , G 196-3 A ,
2M J1155-7919 A , HD 97334 A , β Cir A , HIP 77900 A , USco 1602-2401 A , USco 1610-1913 A , USco 1612-1800 A , and
2M J2126-81 A , are all listed asexoplanet host stars in the
EPE , whose substellar companions were detected and characterized in thisstudy, using data from the Gaia DR2. •
2M J1101-7732 A ,
2M J1450-7841 A ,
2M 1510 A are all brown dwarfs, which are listed as exoplanethosts in the
EPE , whose substellar companions were detected and characterized in this study with GaiaDR2 data. ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . T h e r e l a ti v ea s t r o m e t r y a nd W D S s t a t u s o f a ll d e t ec t e d c o m p a n i on s . C o m p a n i on ρ P A ∆ π s i g - µ r e l s i g - c p m - no ti n [ a r c s ec ][ ◦ ][ m a s ] ∆ π [ m a s / y r] µ r e l i n d e x W D S HD C . ± . . ± . . ± . . ( . ) . ± . . G li e s e B . ± . . ± . . ± . . ( . ) . ± . HD B . ± . . ± . . ± . . ( . ) . ± . . HD B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) H R B . ± . . ± . . ± . . ( . ) . ± . (cid:70) HD B . ± . . ± . . ± . . ( . ) . ± . K - A . ± . . ± . . ± . . ( . ) . ± . . (cid:70) HD B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) HD A . ± . . ± . . ± . . ( . ) . ± . (cid:70) H II C . ± . . ± . . ± . . ( . ) . ± . . (cid:70) H II D . ± . . ± . . ± . . ( . ) . ± . . (cid:70) HA T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) F U T a u B . ± . . ± . . ± . . ( . ) . ± . . DH T a u C . ± . . ± . . ± . . ( . ) . ± . . E r i B ( S B ) . ± . . ± . . ± . . ( . ) . ± . M + A B . ± . . ± . . ± . . ( . ) . ± . . NG T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) A B D o r B D . ± . . ± . . ± . . ( . ) . ± . HD B . ± . . ± . . ± . . ( . ) . ± . NG T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) L P up B . ± . . ± . . ± . . ( − ) . ± . . (cid:70) H I P B . ± . . ± . . ± . . ( . ) . ± . W A SP - B . ± . . ± . . ± . . ( . ) . ± . . HD A . ± . . ± . . ± . . ( . ) . ± . HD B . ± . . ± . . ± . . ( . ) . ± . (cid:70) T O I B . ± . . ± . . ± . . ( . ) . ± . . G - B . ± . . ± . . ± . . ( . ) . ± . . LTT B . ± . . ± . . ± . . ( . ) . ± . . M A S C A R A - B . ± . . ± . . ± . . ( . ) . ± . (cid:70) M J - B . ± . . ± . . ± . . ( . ) . ± . . W A SP - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d C o m p a n i on ρ P A ∆ π s i g - µ r e l s i g - c p m - no ti n [ a r c s ec ][ ◦ ][ m a s ] ∆ π [ m a s / y r] µ r e l i n d e x W D S C HX R C . ± . . ± . . ± . . ( . ) . ± . . (cid:70) G J B . ± . . ± . . ± . . ( . ) . ± . HD BC . ± . . ± . . ± . . ( . ) . ± . . HD B . ± . . ± . . ± . . ( . ) . ± . M J - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) NG T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) M J - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) W A SP - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) H I P D . ± . . ± . . ± . . ( . ) . ± . . (cid:70) T O I B . ± . . ± . . ± . . ( . ) . ± . M B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) β C i r B . ± . . ± . . ± . . ( . ) . ± . . K ELT - B . ± . . ± . . ± . . ( . ) . ± . (cid:70) K - C . ± . . ± . . ± . . ( . ) . ± . . (cid:70) GQ L up C . ± . . ± . . ± . . ( . ) . ± . . H I P B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) U S c o1602 - B . ± . . ± . . ± . . ( . ) . ± . . H I P C . ± . . ± . . ± . . ( . ) . ± . . (cid:70) U S c o1610 - B . ± . . ± . . ± . . ( . ) . ± . . U S c o1612 - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) R OX s C . ± . . ± . . ± . . ( . ) . ± . . (cid:70) HA T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) G J B . ± . . ± . . ± . . ( . ) . ± . HD B . ± . . ± . . ± . . ( . ) . ± . W e nd e l s t e i n - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) M J - B . ± . . ± . . ± . . ( . ) . ± . . T O I B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) NG T S - B . ± . . ± . . ± . . ( . ) . ± . . (cid:70) D S T u c B . ± . . ± . . ± . . ( . ) . ± . R X S J + C . ± . . ± . . ± . . ( . ) . ± . . ichel & Mugrauer Stellar companions of exoplanet hosts
Comments on individual companions:
1: This companion was first reported by Vanderburg et al. (2019), who have already verified itsequidistance and common proper motion with the exoplanet host star HR 858 A using Gaia DR2data, consistent with the results, obtained in this study.2: This companion was detected by Feinstein et al. (2019) and its companionship with the exoplanet hoststar K2-288 B was proven with Gaia DR2 astrometry, confirmed by the astrometric analysis, carriedout in the study, presented here.3: This star was already noticed in the Gaia DR2 by McCormac et al. (2020) as common proper motioncompanion of the exoplanet host star NGTS-10 A, consistent with the results, derived in this study.4: This companion of the exoplanet host star HD 85628 A was discovered by Dorval et al. (2020) in theGaia DR2, who found its parallax and proper motion consistent with that of the exoplanet host star,confirmed by the astrometric analysis, presented here.5: This companion was detected with AO imaging by Rodriguez et al. (2019) using Keck/NIRC 2, but isalso listed in the Gaia DR2, whose astrometry was used by this team to verify the equidistance andcommon proper motion of this companion with the exoplanet host star MASCARA-3 A, as done inthis study.6: This companion was already reported by Nielsen et al. (2019), who proved its companionship with theexoplanet host star WASP-175 A with Gaia DR2 astrometry, consistent with the results derived here.7: The equidistance and common proper motion of this substellar object with the exoplanet host star2M J1155-7919 A was verified by Dickson-Vandervelde et al. (2020) using Gaia DR2 data, as done inthis work.8: This companion was detected by Burgasser et al. (2017) and its common proper motion with the browndwarf 2M J1450-7841 A, listed in the
EPE , was verified with ground based astrometry, confirmed inthis study with Gaia DR2 data, which furthermore proves the equidistance of both objects.9: This companion was noticed by Triaud et al. (2020) in the Gaia DR2 as equidistant and co-movingcompanion of the brown dwarf 2M 1510 A, which is listed in the
EPE , consistent with our results.10: KELT-23 B was first discovered by (Johns et al., 2019) with Keck/NIRC 2 AO imaging, who usedGaia DR2 astrometry to prove the equidistance and common proper motion of the companion with theexoplanet host star KELT-23 A, as done in this study.11: This companion was already described by Hjorth et al. (2019), who have verified it to be equidistantand co-moving with the exoplanet host star K2-290 A, using Gaia DR2 data, a conclusion, which isconfirmed by the analysis, presented here. Furthermore, this team identified an additional but closerstellar companion-candidate of the exoplanet host star (K2-290 B) with Subrau/IRCS AO imaging,which however still needs astrometric confirmation of its companionship. Due to its close angularseparation to K2-290 A we adopt here this object as companion of the exoplanet host star.12: This companion was revealed spectro-photometrically by Aller et al. (2013). With Gaia DR2 astrometrywe prove here its companionship with the exoplanet host star HIP 77900 A.13: HIP 79098 C was reported by (Janson et al., 2019) as equidistant and co-moving companion of theexoplanet host star HIP 79098 A, based on its Gaia DR2 astrometry, confirmed by the analysis of thecompanion, which is presented here. ichel & Mugrauer Stellar companions of exoplanet hosts
14: This companion was revealed spectro-photometrically by Aller et al. (2013). The equidistance andcommon proper motion of this companion with the exoplanet host star USco 1612-1800 A was provenin this study, with Gaia DR2 astrometry.15: This star was identified by (Bowler et al., 2017) as companion of ROXs 12 A, based on its radialvelocity and proper motion. We prove the equidistance of both stars with their Gaia DR2 astrometry,which also confirms their common proper motion.16: This companion was reported by (Hartman et al., 2020), who used the Gaia DR2 astrometry to confirmits companionship with the exoplanet host star HATS-48 A, as done in this work.17: NGTS-7 B was revealed by (Jackman et al., 2019) as companion of the exoplanet host star NGTS-7 Ausing Gaia DR2 astrometry, as done in this study. ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . T h ee qu a t o r i a l c oo r d i n a t e s a ndd e r i v e dphy s i ca l p r op e r ti e s o f a ll d e t ec t e d c o m p a n i on s . C o m p a n i on α δ M G s e p m a ss T e ff F l a g s [ ◦ ][ ◦ ][ m a g ][ a u ][ M (cid:12) ][ K ] HD C . . . + . − . . + . − . + − BPRPPRI G li e s e B . . . + . − . . + . − . + − HD B . − . . + . − . . + . − . + − HD B . − . . + . − . . + . − . + − H R B . − . . + . − . . + . − . + − BPRPPRI HD B . − . . + . − . . + . − . + − K - A . . . + . − . . + . − . + − HD B . − . . + . − . . + . − . + − HD A . − . . + . − . . + . − . + − H II C . . . + . − . . + . − . + − H II D . . . + . − . . + . − . + − BD2MABPRP*** HA T S - B . − . . + . − . . + . − . + − F U T a u B . . . + . − . . + . − . + − BD2MABPRP DH T a u C . . . + . − . . + . − . + − E r i B ( S B ) . − . . + . − . . + . − . + − M + A B . . . + . − . . + . − . + − NG T S - B . − . . + . − . . + . − . + − A B D o r B D . − . . + . − . . + . − . + − HD B . − . . + . − . . + . − . + − NG T S - B . − . . + . − . . + . − . + − L P up B . − . . + . − . . + . − . + − H I P B . − . . + . − . ∼ . WD2MABPRPPRI W A SP - B . − . . + . − . . + . − . + − HD A . . . + . − . . + . − . + − ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d C o m p a n i on α δ M G s e p m a ss T e ff F l a g s [ ◦ ][ ◦ ][ m a g ][ a u ][ M (cid:12) ][ K ] HD B . − . . + . − . . + . − . + − BPRPPRI T O I B . . . + . − . . + . − . + − G - B . . . + . − . . + . − . + − BD2MABPRP
LTT B . − . . + . − . . + . − . + − M A S C A R A - B . . . + . − . . + . − . + − M J - B . − . . + . − . . + . − . + − BD W A SP - B . − . . + . − . . + . − . + − C HX R C . − . . + . − . . + . − . + − G J B . . . + . − . . + . − . + − HD BC . . . + . − . . + . − . + − BD2MABPRP HD B . . . + . − . . + . − . + − M J - B . − . . + . − . . + . − . + − BD2MABPRP NG T S - B . . . + . − . . + . − . + − M J - B . − . . + . − . . + . − . + − BD2MABPRP W A SP - B . − . . + . − . . + . − . + − H I P D . − . . + . − . . + . − . + − T O I B . − . . + . − . . + . − . + − M B . − . . + . − . . + . − . + − BD2MABPRP β C i r B . − . . + . − . . + . − . + − BD2MABPRP K ELT - B . . . + . − . . + . − . + − K - C . − . . + . − . . + . − . + − GQ L up C . − . . + . − . . + . − . + − H I P B . − . . + . − . . + . − . + − BDBPRP U S c o1602 - B . − . . + . − . . + . − . + − ichel & Mugrauer Stellar companions of exoplanet hosts T a b l e . c on ti nu e d C o m p a n i on α δ M G s e p m a ss T e ff F l a g s [ ◦ ][ ◦ ][ m a g ][ a u ][ M (cid:12) ][ K ] H I P C . − . . + . − . . + . − . + − U S c o1610 - B . − . . + . − . . + . − . + − BD2MABPRP U S c o1612 - B . − . . + . − . . + . − . + − BDBPRP R OX s C . − . . + . − . . + . − . + − HA T S - B . − . . + . − . . + . − . + − G J B . . . + . − . . + . − . + − HD B . − . . + . − . . + . − . + − W e nd e l s t e i n - B . . . + . − . . + . − . + − M J - B . − . . + . − . . + . − . + − BD2MABPRP T O I B . − . . + . − . . + . − . + − NG T S - B . − . . + . − . . + . − . + − D S T u c B . − . . + . − . . + . − . + − R X S J + C . . . + . − . . + . − . + − T a b l e F oo t n o t e s : : M + B i s ac l o s e b r o w nd w a rf c o m p a n i ono f M + A . : HD BC i s a b i n a r yb r o w nd w a rf s y s t e m . : T h e b r o w nd w a rf U S c o1602 - B w a s d e t ec t e dby A ll e r e t a l . ( ) a nd it s po ss i b l ec o m p a n i on s h i p t o U S c o1602 - A , w a s r e v ea l e d w it hpho t o m e t r y a nd f o ll o w - up s p ec t r o s c opy , w h i c h w a s fi n a ll yp r ov e n i n t h i ss t udy w it h t h e G a i a D R a s t r o m e t r yo f t h ec o m p a n i on , i . e . c on fi r m a ti ono f e qu i d i s t a n ce , a nd c o mm onp r op e r m o ti on , a s w e ll a s t e s t f o r g r a v it a ti on a l s t a b ilit y . U S c o1602 - B i s on e o f r e po r t e d s ub s t e ll a r c o m p a n i on s , d e t ec t e dby G a i a , w h i c h w e r ea l s o c h a r ac t e r i ze d i n t h i ss t udyu s i ng t h e i r G a i a D R a s t r o - a ndpho t o m e t r y . I ng e n e r a l , t h e d e r i v e d m a ss o f t h e s e s ub s t e ll a r c o m p a n i on s a g r ee s w e ll w it h t h e m a ss g i v e n i n t h e lit e r a t u r e , w it h a d e v i a ti ono f on l y a f e w M J u p , on a v e r a g e . I n c on t r a s t , f o r U S c o1602 - B A ll e r e t a l . ( ) d e r i v e d a m a ss o f + − M J u p a t a n a g e o f M y r( + − M J u p a t M y r) a dop ti ng a d i s t a n ce o f a bou t ca ndno e x ti n c ti on . W it h t h e G a i a D R a r a ll a x a nd t h e S t a r ho r s ee x ti n c ti on e s ti m a t e o f t h e p r i m a r y s t a r a nd t h e G - b a nd pho t o m e t r yo f t h ec o m p a n i on w e ob t a i n e d a s i gn i fi ca n tl yh i gh e r m a ss o f . + . − . M (cid:12) a t M y r( . + . − . M (cid:12) a t M y r) . A dop ti ng A G = m a gy i e l d s a m a ss o f t h ec o m p a n i ono f . + . − . M (cid:12) f o r M y r , a nd . + . − . M (cid:12) f o r M y r , r e s p ec ti v e l y . T h e r e f o r e , w ec l a ss i f y t h i s c o m p a n i onh e r ea s l o w - m a sss t a r . ichel & Mugrauer Stellar companions of exoplanet hosts
Table 5.
List of all detected companions, whose differential proper motion µ rel exceeds their estimatedescape velocity µ esc . Companion µ rel µ esc [ mas/yr ] [ mas/yr ]
51 Eri B (SB) . ± .
71 11 . ± . ***HIP 38594 B . ± .
24 4 . ± . TOI 905 B . ± .
76 3 . ± . Figure 1.
The histograms of the individual properties of all targets of this study. ichel & Mugrauer Stellar companions of exoplanet hosts m a ss ( M A SS ) [ M ⊙ ] mass (G-band) [M ⊙ ] Figure 2.
Comparison of the mass of the detected companions, derived from their G-band and infrared2MASS photometry. ichel & Mugrauer Stellar companions of exoplanet hosts F sep [au] Figure 3.
The cumulative distribution function of the projected separation ( sep ) of all detected companionsto the associated exoplanet hosts. ichel & Mugrauer Stellar companions of exoplanet hosts F M Comp [M ☉☉ ] Figure 4.
The cumulative distribution function of the mass of all companions, detected in this study. ichel & Mugrauer Stellar companions of exoplanet hosts F T eff [K] Figure 5.
The cumulative distribution function of the effective temperature of all detected companions. ichel & Mugrauer Stellar companions of exoplanet hosts M C o m p [ M ⊙⊙ ] sep [au]
100 1000 10000
Figure 6.
The mass of all companions, detected in this study, plotted over their projected separation ( sep )to the associated exoplanet hosts. The white dwarf companion HIP 38594 B, is illustrated as open circle. ichel & Mugrauer Stellar companions of exoplanet hosts | (cid:2) G | [ m ag ] (cid:3) [arcsec]G<12.8 magG>12.8 mag Figure 7.