We present an analysis of 32 high-resolution echelle spectra of the premain sequence spectroscopic binary AK Sco obtained during 1998 and 2000, as well as a total of 71 photoelectric radial-velocity observations from the period 1986–1994. These data allow considerable improvement of the period and other orbital parameters of AK Sco. Our analysis also includes eight series of photometric observations in the uvby and Geneva seven-color systems. No eclipses or other periodic variations are seen in the photometry, but the well-determined HIPPARCOS parallax allows us to constrain the orbital inclination of the system and obtain physical parameters for the two stars.
Disk models have been fitted to the spectral energy distribution of AK Sco from 350 nm to 1100 μm. The stellar parameters permit a consistent solution with an inner rim temperature of 1250 K, instead of the usual 1500 K corresponding to the dust evaporation temperature. Dynamical e ects due to tidal interaction of the binary system are supposed to be responsible for pushing the disk inner radius outwards.
The spectrum of AK Sco exhibits emission and absorption lines that show substantial variety and variability in shape. The system displays variations at the binary orbital period in the Hα equivalent width, although with appreciable scatter. We find no evidence of enhanced accretion near the periastron passage in AK Sco as expected theoretically and observed previously in DQ Tau, a similarly young binary system with a mass ratio near unity and an eccentric orbit.