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's orbiting the primary in a clockwise orbit, lying nearly in the plane of the sky (i.e., nearly perpendicular to the orbital plane of the transiting planet), and with period of about 3200 years.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science
- Binaries: close
- Planetary systems
- Stars: individual (HD 189733, HD 189733B)
- Stars: low-mass, brown dwarfs