A Lucky Imaging search for stellar sources near 74 transit hosts
AAstronomy & Astrophysics manuscript no. TEP˙CAHA˙2 c (cid:13)
ESO 2018February 21, 2018
A Lucky Imaging search for stellar sources near transit hosts (cid:63) Maria W¨ollert and Wolfgang Brandner Max-Planck-Institut f¨ur Astronomie, K¨onigstuhl 17, 69117 Heidelberg, Germanye-mail: [email protected]
Received —; accepted —
ABSTRACT
Context.
Many transiting planet host stars lack high resolution imaging and thus close stellar sources can be missed. Those unknownstars potentially bias the derivation of the planetary and stellar parameters from the transit light curve, no matter if they are bound ornot. In addition, bound stellar companions interact gravitationally with the exoplanet host star, the disk and the planets and can thusinfluence the formation and evolution of the planetary system strongly.
Aims.
We extended our high-resolution Lucky Imaging survey for close stellar sources by 74 transiting planet host stars. 39 of thesestars lack previous high-resolution imaging, 23 are follow up observations of companions or companion candidates, and the remainingstars have been observed by others with AO imaging though in di ff erent bands. We determine the separation of all new and knowncompanion candidates and estimate the flux ratio in the observed bands. Methods.
All observations were carried out with the Lucky Imaging camera AstraLux Norte at the Calar Alto 2 . i (cid:48) and z (cid:48) passbands. Results.
We find new stellar sources within 1 (cid:48)(cid:48) to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, and WASP-103 and between 1 (cid:48)(cid:48) and4 (cid:48)(cid:48) to HAT-P-29, and WASP-56.
Key words.
Techniques: high angular resolution – Binaries: visual – Planetary systems
1. Introduction
During the last 15 years, more than 1000 confirmed and sev-eral 1000 candidate exoplanets have been found by ground- andspace-based transit searches as HATNet (Bakos et al. 2004),SuperWasp (Pollacco et al. 2006), CoRoT (Baglin et al. 2006),and Kepler (Borucki et al. 2010; Batalha et al. 2013; Burke et al.2014). Transiting exoplanets (TEPs) o ff er the unique opportu-nity to determine a variety of planetary properties as true mass,mean density and surface gravity. They also allow to characterizethe planet’s atmosphere through spectroscopy, to determine theplanet’s temperature in secondary eclipse observations, and tomeasure the angle between the orbital plane and the stellar rota-tion axis via the Rossiter-McLaughlin e ff ect (Winn et al. 2005).As many transiting planet follow-up observations were lim-ited in angular resolution either due to instrumental limits (like,e.g., SPITZER / IRAC) or - in case of ground-based follow-up- seeing limited, care has to be taken about missing a blendedclose star. This is especially true for faint sources as bright starsmay be recognized in follow-up spectra. Unknown, close starsadd a constant flux to the light-curve which bias both, primaryand secondary eclipse measurements. In the first case, the ad-ditional source leads to an underestimate of the planetary radiusand consequently an overestimate of the planetary density. In thesecond case, the planet infrared emission spectrum can be under-estimated by several tens of percent (e.g Crossfield et al. 2012).Finding close stellar sources to transiting exoplanet host starsis, however, not only crucial to determine the planetary parame-ters correctly, but also to understand the influence of binarity on (cid:63)
Based on observations collected at the German-SpanishAstronomical Center, Calar Alto, jointly operated by the Max-Planck-Institut f¨ur Astronomie Heidelberg and the Instituto deAstrof´ısica de Andaluc´ıa (CSIC). the formation and evolution of planetary systems. Even thoughnot all of the detected, close stars are gravitationally bound, a lotof them are as has been shown via multi-epoch high-resolutionobservations (e.g Narita et al. 2012; Bergfors et al. 2013; Ngoet al. 2015). The e ff ects of binarity may be manifold: Stellarcompanions might stir (Mayer et al. 2005), tilt (Batygin 2012)or truncate the protoplanetary disk (Artymowicz & Lubow 1994)or they can interact with the formed planets via, e.g., the Lidov-Kozai mechanism or other secular interactions (Wu & Murray2003; Fabrycky & Tremaine 2007; Naoz et al. 2011). Stellarcompanions may be thus one important cause for the observedvariety of planetary system architectures.Several groups have already done systematic surveys for stel-lar companions using either the Lucky Imaging method (e.g.Daemgen et al. 2009; Faedi et al. 2013; Bergfors et al. 2013;Lillo-Box et al. 2012, 2014; W¨ollert et al. 2015), speckle imag-ing (e.g. Howell et al. 2011; Horch et al. 2014; Kane et al.2014; Everett et al. 2015), AO-assisted imaging on its own, orcombined with radial velocity methods (e.g. Adams et al. 2012,2013; Guenther et al. 2013; Dressing et al. 2014; Law et al.2014; Wang et al. 2014; Ngo et al. 2015), or search for colour-dependency of the transit depths (e.g. Col´on et al. 2012; D´esertet al. 2015). However, more and more transiting exoplanets arefound and their precise characterisation will enable us to get amore precise view at the important mechanisms that shape plan-etary systems.In this paper we present the results of our ongoing e ff ort tofind stellar sources close to TEP host stars. The observations anddata reductions were performed similarly to our previous paperW¨ollert et al. (2015) and are briefly described in Section 2. InSection 3 we present the astrometric and photometric proper-ties of the observed sources and we summarize our findings inSection 4. a r X i v : . [ a s t r o - ph . S R ] J un aria W¨ollert and Wolfgang Brandner: A LI search for stellar sources near TEP hosts
2. Observations and data reduction
The initial motivation for our survey was to focus on TEPs withalready existing measurements of the Rossiter-McLaughlin ef-fect, and to explore a possible relationship of the angle definedby the spin vectors of the TEP host star and the planetary or-bit, and the presence or absence of a stellar companion. Thisselection criterion was later relaxed to include all TEP host starssu ffi ciently bright (i ≤
13 mag) to facilitate high-quality LuckyImaging. The majority of the targets were selected from TEPseither identified by the SuperWASP or the HatNet project. Thiswas complemented by TEP hosts identified in other ground- orspace-based surveys. We focused on stars without previous high-angular resolution observations, as well as on TEP host starswith previous detections of stellar companion candidates in or-der to derive constraints on the relative astrometry between TEPhost and stellar companion candidate.
All observations were carried out at Calar Alto with the 2 . i (cid:48) and z (cid:48) -passbands usingthe same set-up as described in W¨ollert et al. (2015). The fieldof view was 12 (cid:48)(cid:48) by 12 (cid:48)(cid:48) with the exoplanet host star separatedat least 4 (cid:48)(cid:48) from the image borders. Depending on the targetbrightness and observing conditions we took between 10000 and54000 individual frames with exposure times of 15 ms each sothat the probability of getting a stable speckle pattern is suf-ficiently large. The individual AstraLux images are dark sub-tracted and flat-fielded. For the data analysis we chose the 10%of images with the highest Strehl ratio and combined them usingthe shift-and-add technique.In order to precisely measure the separation and position an-gle of the companion candidates we took at least 3 images of theglobular cluster M 13 each night. Using IRAF imexamine wedetermined the detector position of 5 widely separated stars inthe field and calculated their separation and rotation angle pair-wise. The result was compared to the values from high-qualityastrometric HST / ACS observations. As the instrument was notunmounted during the observing nights in March 2015, we usedthe images of all three nights for the calibration of that run. Theplate scale and detector rotation were 23 . ± .
01 mas / px and1 . ◦ ± . ◦ west of north and 23 . ± .
01 mas / px and 2 . ◦ ± . ◦ west of north for the observations in October 2014 and March2015, respectively. To find all stellar sources, also those which are faint and closeto the transiting planet host star, we first subtracted the pointspread function (PSF) of the TEP host. As the PSFs vary signif-icantly from image to image and no standard PSF can be usedfor all observations, we fitted a theoretical model PSF to eachstar. The theoretical model PSF comprises the PSF from an idealtelescope without atmosphere which is then convolved with aGaussian and finally added to a Mo ff at profile. The model alsoweights the two PSF components (see W¨ollert et al. 2014, formore information on the procedure). If a companion candidatewas found, we fitted a scaled and di ff erently weighted PSF to it to determine its position and the flux ratio of the two compo-nents. We used the PSF subtracted images additionally to calcu-late the 5 σ -contrast curve. For this purpose, we divided the fluxin a box of 5 × r = . (cid:48)(cid:48) , . (cid:48)(cid:48) , . (cid:48)(cid:48) , and2 . (cid:48)(cid:48) of targets with candidate companions is given in Table 1,the contrast for all other targets is given in Table 2. Outside of2 . (cid:48)(cid:48) , the contrast decreases only very little and the value givenfor 2 . (cid:48)(cid:48) can be assumed.The flux ratio in both passbands was measured using the IDLroutine APER which performs aperture photometry. We used anaperture size of 4 . ×
50 px sized box in one corner of the imagewithout stellar source for the primary and at the opposite posi-tion of the TEP host with the same distance and aperture size forthe fainter companion. This ensures that the flux contribution ofthe brighter TEP host is accurately subtracted from those of thefainter source as our PSFs are almost point symmetrical in shape.The uncertainties of the flux ratios are propagated from the sta-tistical photometric errors given by APER and systematic errorsfrom using this method. The latter were estimated by comparingthe results obtained by using di ff erent aperture sizes as well asthe flux ratios determined by PSF-fitting.
3. Results
To the 74 observed TEP host stars we find new companioncandidates to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, andWASP-103 within 1 (cid:48)(cid:48) , to HAT-P-29 and WASP-56 within 4 (cid:48)(cid:48) ,and the candidates of HAT-P-15, HAT-P-54, and Kepler-89 aresituated outside of 4 (cid:48)(cid:48) . Images in z (cid:48) of all these sources can befound in Figure 1. In addition, we did follow-up observations of23 already known companion candidates. The astrometric posi-tions and flux ratios in i (cid:48) and z (cid:48) of all companion candidates canbe found in Table 3.As can be seen in Table 3, most sources appear to be red-der than the primary which would be expected for a lower masscompanion. The uncertainties are, however, too large to allowa precise estimate of the spectral type. To achieve this, adap-tive optics based observations or spectra would be needed. Theknowledge of the companion candidate spectral type would thenallow to correct the planetary parameter and infrared emissionspectra of the new close companions, as well as to compare theirphotometric distance to those of the TEP host star to investigatewhether the sources may be gravitationally bound or not. For thispurpose their astrometric position needs to be followed up in theupcoming years as well.
4. Summary
In our ongoing Lucky Imaging search for stellar sources close totransiting exoplanet host stars we identified 5 new, close sourceswithin 1 (cid:48)(cid:48) to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, andWASP-103 which have been overlooked so far. The planetaryand stellar parameters and thermal radiation profile of the tran-siting planets of these sources may have to be corrected accord-ing to the spectral type of the companion candidate star whichremains to be determined. Also the detected companion candi-dates to HAT-P-29 and WASP-56 which are located at 3 . (cid:48)(cid:48) and Table 1: TEP hosts with detection, radial contrast limits, references to other high-resolution imaging papers if available σ detection limit ( ∆ z (cid:48) [mag])Name 0 . (cid:48)(cid:48) . (cid:48)(cid:48) . (cid:48)(cid:48) . (cid:48)(cid:48) ref.New companion candidatesHAT-P-15 4.28 5.37 6.40 6.90 Ngo et al. (2015) ∗ HAT-P-27 / WASP-40 3.90 4.82 5.75 6.20 W¨ollert et al. (2015) (cid:63)
HAT-P-28 3.24 3.94 4.76 5.12HAT-P-29 4.05 4.72 5.45 5.95 Ngo et al. (2015) (cid:63)
HAT-P-35 2.81 3.37 3.94 4.11HAT-P-54 3.57 4.41 5.13 5.52Kepler-89 3.10 3.60 4.28 4.69 Adams et al. (2012) ∗ ; Lillo-Box et al. (2014) ∗ WASP-56 4.08 4.89 5.78 6.11WASP-76 3.81 4.79 6.21 7.18WASP-103 3.75 4.55 5.48 5.90Known companion candidatesCoRoT-02 2.97 3.46 4.16 4.78 Alonso et al. (2008); Faedi et al. (2013); W¨ollert et al. (2015)CoRoT-03 2.85 3.22 3.65 3.97 Deleuil et al. (2008); Faedi et al. (2013); W¨ollert et al. (2015)CoRoT-11 3.25 3.85 4.65 4.97 Gandolfi et al. (2010); W¨ollert et al. (2015)HAT-P-20 3.64 4.30 5.22 5.97 Ngo et al. (2015) ∗ ; Bakos et al. (2011) † HAT-P-24 3.51 4.39 5.11 5.67 Ngo et al. (2015)HAT-P-30 4.01 5.06 6.09 6.72 Adams et al. (2013); Ngo et al. (2015)HAT-P-32 3.78 4.61 5.35 5.84 Adams et al. (2013); Ngo et al. (2015); W¨ollert et al. (2015) (cid:63)
HAT-P-41 3.24 3.62 4.37 4.97 Hartman et al. (2012); W¨ollert et al. (2015)KELT-2 3.75 4.61 6.13 7.03 Beatty et al. (2012) † KELT-3 3.95 4.75 5.45 5.95 Pepper et al. (2013)Kepler-13 3.33 4.11 4.87 5.54 Santerne et al. (2012)KIC10905746 3.33 3.78 4.56 5.09 Fischer et al. (2012)LHS-6343 2.72 3.19 3.73 4.40 Johnson et al. (2011); Montet et al. (2015)TrES-4 6.13 6.09 6.07 6.13 Daemgen et al. (2009); Bergfors et al. (2013); Faedi et al. (2013) ;W¨ollert et al. (2015); Ngo et al. (2015)WASP-11 3.80 4.81 5.70 6.25 Ngo et al. (2015)WASP-12 4.03 4.78 5.56 6.12 Crossfield et al. (2012); Bergfors et al. (2013); Bechter et al. (2014)WASP-14 4.26 5.29 6.82 7.70 W¨ollert et al. (2015); Ngo et al. (2015)WASP-33 3.33 4.77 6.64 7.90 Moya et al. (2011); Adams et al. (2013)WASP-36 3.38 4.34 4.84 5.16 Smith et al. (2012) † WASP-70 3.07 3.52 4.26 4.90 Anderson et al. (2014) † WASP-77 3.71 4.54 5.60 6.42 Maxted et al. (2013)WASP-85 4.25 5.26 6.21 7.12 Brown et al. (2014) † XO-3 4.11 4.91 5.79 6.33 Bergfors et al. (2013); Adams et al. (2013); Ngo et al. (2015) ∗∗ : Outside FoV, (cid:63) : no detection, † : seeing limited observation or catalog data . (cid:48)(cid:48) respectively to the TEP host could have this influence as thephotometric aperture used for the transit observations, e.g. withSPITZER, are about that size. The sources that are outside of4 (cid:48)(cid:48) to HAT-P-15, HAT-P-54, and Kepler-89 do not influence theplanetary and stellar property derivation from transit light curve,but can be of interest if they happen to be bound to the TEP host.This needs to be investigated with astrometric observations overthe upcoming years. In this work, we also give the astrometricpositions and i (cid:48) and z (cid:48) flux ratios of 23 already known compan-ion candidates. Acknowledgements.
MW acknowledges support by the International MaxPlanck Research School for Astronomy & Cosmic Physics in Heidelberg(IMPRS-HD).
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Table 2: TEP hosts with no detection, radial contrast limits, references to other high-resolution imaging papers if available σ detection limit ( ∆ z (cid:48) [mag])Name 0 . (cid:48)(cid:48) . (cid:48)(cid:48) . (cid:48)(cid:48) . (cid:48)(cid:48) ref.55˙Cnc 2.90 2.70 3.04 3.85 Roell et al. (2012)CoRoT-01 3.23 3.81 4.34 4.70 Adams et al. (2013)CoRoT-07 3.81 4.47 5.26 5.80 Guenther et al. (2013)CoRoT-24 2.78 3.26 3.44 3.51 Guenther et al. (2013)EPIC-201367065 4.16 4.98 5.99 6.69 Crossfield et al. (2015)EPIC-201505350 3.77 4.56 5.43 5.77GJ3470 4.01 4.97 5.61 5.96HAT-P-09 3.31 4.24 4.77 5.24HAT-P-25 3.80 4.72 5.57 5.80 Adams et al. (2013)HAT-P-33 3.86 4.60 5.29 5.80 Adams et al. (2013); Ngo et al. (2015)HAT-P-38 3.59 4.46 5.22 5.61HAT-P-39 3.28 4.23 4.87 5.32HAT-P-42 1.79 2.25 2.95 3.44HAT-P-43 3.33 4.18 4.82 5.12HAT-P-44 3.73 4.64 5.40 5.67HAT-P-45 3.43 4.12 4.75 5.11HAT-P-46 3.97 4.64 5.50 5.94HAT-P-49 2.83 3.38 3.98 4.64KELT-1 3.65 4.19 5.14 5.88 Siverd et al. (2012)KELT-6 4.07 5.14 6.37 7.19 Collins et al. (2014)KELT-7 3.80 5.45 6.78 7.70 Bieryla et al. (2015)Kepler-63 3.59 4.36 5.36 5.73 Sanchis-Ojeda et al. (2013)KOI-1474 2.79 3.33 3.79 4.16Qatar-2 3.59 4.32 5.12 5.47TrES-5 2.94 3.48 3.93 4.30WASP-30 3.28 3.72 4.63 5.11WASP-32 3.47 4.10 5.11 5.56WASP-35 3.72 4.42 5.37 5.98WASP-43 3.80 4.63 5.37 5.96WASP-44 2.85 3.37 4.08 4.47WASP-50 3.42 3.97 4.79 5.25WASP-54 4.04 5.02 6.22 6.93WASP-57 3.56 4.63 5.29 5.46WASP-65 3.89 4.73 5.63 6.09WASP-69 3.62 4.39 5.13 5.65WASP-71 3.59 4.17 5.22 5.94WASP-82 3.89 4.80 5.81 6.64WASP-84 3.90 4.91 5.81 6.66WASP-90 2.83 3.33 3.85 4.36WASP-104 3.99 4.88 5.75 6.31WASP-106 3.77 4.56 5.41 5.96 Faedi, F., Staley, T., G´omez Maqueo Chew, Y., et al. 2013, MNRAS, 433, 2097Fischer, D. A., Schwamb, M. E., Schawinski, K., et al. 2012, MNRAS, 419, 2900Gandolfi, D., H´ebrard, G., Alonso, R., et al. 2010, A&A, 524, A55Guenther, E. W., Fridlund, M., Alonso, R., et al. 2013, A&A, 556, A75Hartman, J. D., Bakos, G. ´A., B´eky, B., et al. 2012, AJ, 144, 139Horch, E. P., Howell, S. B., Everett, M. E., & Ciardi, D. R. 2014, ApJ, 795, 60Hormuth, F., Brandner, W., Hippler, S., & Henning, T. 2008, Journal of PhysicsConference Series, 131, 012051Howell, S. B., Everett, M. E., Sherry, W., Horch, E., & Ciardi, D. R. 2011, AJ,142, 19Johnson, J. A., Apps, K., Gazak, J. Z., et al. 2011, ApJ, 730, 79Kane, S. R., Howell, S. B., Horch, E. P., et al. 2014, ApJ, 785, 93Law, N. M., Morton, T., Baranec, C., et al. 2014, ApJ, 791, 35Lillo-Box, J., Barrado, D., & Bouy, H. 2012, A&A, 546, A10Lillo-Box, J., Barrado, D., & Bouy, H. 2014, A&A, 566, A103Maxted, P. F. L., Anderson, D. R., Collier Cameron, A., et al. 2013, PASP, 125,48Mayer, L., Wadsley, J., Quinn, T., & Stadel, J. 2005, MNRAS, 363, 641Montet, B. T., Johnson, J. A., Muirhead, P. S., et al. 2015, ApJ, 800, 134Moya, A., Bouy, H., Marchis, F., Vicente, B., & Barrado, D. 2011, A&A, 535,A110Naoz, S., Farr, W. M., Lithwick, Y., Rasio, F. A., & Teyssandier, J. 2011, Nature,473, 187 Narita, N., Takahashi, Y. H., Kuzuhara, M., et al. 2012, PASJ, 64, L7Ngo, H., Knutson, H. A., Hinkley, S., et al. 2015, ApJ, 800, 138Pepper, J., Siverd, R. J., Beatty, T. G., et al. 2013, ApJ, 773, 64Pollacco, D. L., Skillen, I., Collier Cameron, A., et al. 2006, PASP, 118, 1407Roell, T., Neuh¨auser, R., Seifahrt, A., & Mugrauer, M. 2012, A&A, 542, A92Sanchis-Ojeda, R., Winn, J. N., Marcy, G. W., et al. 2013, ApJ, 775, 54Santerne, A., Moutou, C., Barros, S. C. C., et al. 2012, A&A, 544, L12Siverd, R. J., Beatty, T. G., Pepper, J., et al. 2012, ApJ, 761, 123Smith, A. M. S., Anderson, D. R., Collier Cameron, A., et al. 2012, AJ, 143, 81Wang, J., Fischer, D. A., Xie, J.-W., & Ciardi, D. R. 2014, ApJ, 791, 111Winn, J. N., Noyes, R. W., Holman, M. J., et al. 2005, ApJ, 631, 1215W¨ollert, M., Brandner, W., Bergfors, C., & Henning, T. 2015, A&A, 575, A23W¨ollert, M., Brandner, W., Re ff ert, S., et al. 2014, A&A, 564, A10Wu, Y. & Murray, N. 2003, ApJ, 589, 605 Table 3: TEP hosts with candidate companions, observing date, inferred astrometric position and flux ratio in the observed pass-bands. In the last column we indicate whether the companion was announced previously.
Name Date of obs. Sep [ (cid:48)(cid:48) ] PA [ ◦ ] ∆ i (cid:48) [mag] ∆ z (cid:48) [mag] new?CoRoT-02 21.10.2014 4 . ± .
025 208 . ± .
14 3 . ± .
15 3 . ± . . ± .
013 175 . ± .
55 3 . ± .
25 3 . ± . . ± .
005 307 . ± .
17 2 . ± .
09 2 . ± . . ± .
026 233 . ± .
54 7 . ± .
49 6 . ± .
45 yes07.03.2015 6 . ± .
014 235 . ± . − . ± . . ± .
014 194 . ± . − . ± .
20 yesHAT-P-20 21.10.2014 6 . ± .
012 321 . ± .
11 2 . ± .
08 1 . ± . . ± .
008 171 . ± .
60 6 . ± .
18 5 . ± . / WASP-40 27.06.2013 † . ± .
021 25 . ± . (cid:63) (cid:63) yes09.03.2015 0 . ± .
007 28 . ± . − . ± . . ± .
019 212 . ± .
05 6 . . ± .
27 yesHAT-P-29 06.03.2015 3 . ± .
104 160 . ± .
36 7 . ± .
25 6 . ± .
35 yes21.10.2014 3 . ± .
050 161 . ± .
36 6 . ± .
42 6 . ± . . ± .
007 4 . ± .
14 4 . ± .
06 4 . ± . . ± .
009 110 . ± . − . ± . . ± .
010 139 . ± .
23 5 . ± . (cid:63), ◦ yesHAT-P-41 21.10.2014 3 . ± .
011 184 . ± .
15 3 . ± .
13 3 . ± . . ± .
062 135 . ± .
96 5 . ± .
53 5 . ± .
59 yes06.03.2015 4 . ± .
010 135 . ± . (cid:63) . ± . . ± .
008 332 . ± .
15 3 . ± .
09 3 . ± . . ± .
007 332 . ± .
14 2 . ± .
15 3 . ± . . ± .
009 42 . ± .
23 3 . ± .
15 3 . ± . . ± .
003 280 . ± .
22 0 . ± .
02 0 . ± . . ± .
028 108 . ± .
11 3 . ± .
18 3 . ± .
23 yesKIC10905746 21.10.2014 4 . ± .
007 98 . ± .
12 2 . ± .
16 1 . ± . . ± .
006 119 . ± .
30 2 . ± .
24 1 . ± . . ± .
019 0 . ± .
31 4 . ± .
07 4 . ± . . ± .
013 219 . ± .
79 2 . ± .
50 2 . ± . . ± .
033 218 . ± .
41 3 . ± .
26 2 . ± . . ± .
008 250 . ± .
55 4 . ± .
10 3 . ± . . ± .
024 102 . ± .
40 7 . ± .
22 5 . ± . . ± .
012 275 . ± .
71 9 . . ± . . ± .
017 67 . ± .
95 8 . . ± . . ± .
009 113 . ± .
18 6 . ± .
24 5 . ± .
22 yesWASP-70 21.10.2014 3 . ± .
029 167 . ± .
19 2 . ± .
18 2 . ± . . ± .
012 216 . ± .
93 2 . ± .
25 2 . ± .
33 yesWASP-77 21.10.2014 3 . ± .
007 154 . ± .
12 1 . ± .
06 1 . ± . . ± .
003 100 . ± .
19 0 . ± .
01 0 . ± . . ± .
016 132 . ± .
74 3 . ± .
46 2 . ± .
35 yesXO-3 06.03.2015 6 . ± .
081 297 . ± .
13 8 . ± .
28 7 . ± . (cid:63) : companion candidate was too weak for flux measurement † : The source was first not identified by us (W¨ollert et al. 2015), but after the new observation with better contrast it could be located. ◦ : The exposure time in z (cid:48) was five times smaller than the one in i (cid:48) . 5aria W¨ollert and Wolfgang Brandner: A LI search for stellar sources near TEP hosts HAT-P-15 -2 0 2 4arcsec-6-4-20 a r c s ec HAT-P-27 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5arcsec-1.5-1.0-0.50.00.51.01.5 a r c s ec HAT-P-28 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5arcsec-1.5-1.0-0.50.00.51.01.5 a r c s ec HAT-P-29 -3 -2 -1 0 1 2 3arcsec-3-2-1012 a r c s ec HAT-P-35 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5arcsec-1.5-1.0-0.50.00.51.01.5 a r c s ec HAT-P-54 -3 -2 -1 0 1 2arcsec-4-3-2-101 a r c s ec Kepler-89 -6 -4 -2 0arcsec-6-4-202 a r c s ec WASP-56 -4 -2 0 2 4arcsec-4-2024 a r c s ec WASP-76 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5arcsec-1.5-1.0-0.50.00.51.01.5 a r c s ec WASP-103 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5arcsec-1.5-1.0-0.50.00.51.01.5 a r c s ec Fig. 1: The z (cid:48) filter images of the 10 exoplanet host stars for which new companion candidates have been detected with exception ofHAT-P-35 for which the i (cid:48) -image is shown. The grey scale is proportional to the square root of the count. To improve the visibilityof the close companions to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, and WASP-103, we additionally applied unsharp masking.The orientation is identical for all images with North up and East to the left.-image is shown. The grey scale is proportional to the square root of the count. To improve the visibilityof the close companions to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, and WASP-103, we additionally applied unsharp masking.The orientation is identical for all images with North up and East to the left.