Bipolar jets produced by a spectroscopic binary

We present evidence that the spectroscopically identified bipolar jets of the pre-main sequence binary KH 15D (P = 48.4 d, ε 0.6, periastron separation 18 R_A , M_A = 0.6 M _·, M _B = 0.7 M _·) are a common product of the whole binary system, rather than being launched from either star individually. They may be launched from the innermost part of the circumbinary disk (CBD) or may result from the merging of two outflows driven by the individual stars. This evidence is based on high-resolution Hα and [O I]λ6300 line profiles obtained during eclipse phases of this nearly edge-on system. The occultation of star A (the only currently visible star) by the disk strongly suppresses the stellar Hα and continuum emission and allows one to study the faint redshifted and blueshifted emission components of the bipolar jets. The strongest evidence for jet production by the whole binary system comes from the observed radial velocity symmetry of the two jet components relative to the systemic velocity of the binary in combination with current accretion models from the CBD onto a binary system.