A Stellar Companion in the HD 189733 System with a Known Transiting Extrasolar Planet

Gáspár Á. Bakos, András Pál, David W. Latham, Robert W. Noyes, Robert P. Stefanik
2006 Astrophysical Journal  
We show that the very close-by (19 pc) K0 star HD 189733, already found to be orbited by a transiting giant planet, is the primary of a double-star system, with the secondary being a mid-M dwarf with projected separation of about 216 AU from the primary. This conclusion is based on astrometry, proper motion and radial velocity measurements, spectral type determination and photometry. We also detect differential proper motion of the secondary. The data appear consistent with the secondary
more » ... g the primary in a clockwise orbit, lying nearly in the plane of the sky (that is, nearly perpendicular to the orbital plane of the transiting planet), and with period about 3200 years.
doi:10.1086/503671 fatcat:opmcw34hpfhinky5wg2flupshe