Cool dwarfs in wide multiple systems. Paper 3: Two common-proper-motion,
  late-type stars separated by over 11 arcmin
  LP 209-28 and LP 209-27 have similar proper motions as tabulated by several
catalogues. Using seven astrometric epochs spanning 59 years, we confirm a
common tangential velocity by measuring a constant angular separation of rho =
666.62+/-0.09 arcsec. Accurate SDSS and 2MASS photometry indicates that they
are normal dwarfs of approximate spectral types K7 V and M3 V. However, from
their apparent magnitudes, both LP 209-28 and LP 209-27 are located at 200-250
pc, from where one can deduce an astonishing projected physical separation of
0.6-0.8 pc. The system Koenigstuhl 6 AB represents another world record among
the least-bound systems with low-mass star components.
