A search for wide visual companions of exoplanet host stars: The Calar Alto Survey

Mugrauer, M.; Neuhäuser, R.; Mazeh, T.; Guenther, E.; Fernández, M.; Broeg, C.
Astronomische Nachrichten, Vol.327, Issue 4, p.321


We have carried out a search for co-moving stellar and substellar companions around 18 exoplanet host stars with the infrared camera MAGIC at the 2.2 m Calar Alto telescope, by comparing our images with images from the all sky surveys 2MASS, POSS I and II. Four stars of the sample namely HD 80606, 55 Cnc, HD 46375 and BD-10°3166, are listed as binaries in the Washington Visual Double Star Catalogue (WDS). The binary nature of HD 80606, 55 Cnc, and HD 46375 is confirmed with both astrometry as well as photometry, thereby the proper motion of the companion of HD 46375 was determined here for the first time. We derived the companion masses as well as the longterm stability regions for additional companions in these three binary systems. We can rule out further stellar companions around all stars in the sample with projected separations between 270 AU and 2500 AU, being sensitive to substellar companions with masses down to ˜ 60 {MJup} (S/N=3). Furthermore we present evidence that the two components of the WDS binary BD-10°3166 are unrelated stars, i.e this system is a visual pair. The spectrophotometric distance of the primary (a K0 dwarf) is ˜ 67 pc, whereas the presumable secondary BD-10°3166 B (a M4 to M5 dwarf) is located at a distance of 13 pc in the foreground.