For Scorpius-Centaurus, de Zeeuw et al. One cannot distinguish this kind of relative motion from slow orbital motion by analyzing relative velocities. It is, however, not probable that chance projections within the same SFR are a frequent phenomenon, because of the low stellar density in the SFRs discussed here. Leinert et al. This includes association members and field stars.
All companions discussed here are brighter than and have projected separations of less than .
The low observed relative velocities in some systems are probably due to the fact that we can only detect the projected motion on the sky. 3.2.4 Herbig-Haro objects G95 raised the question of whether an appreciable number of companions of young stars detected with only one observation in one broad band filter may in fact not be stellar, but rather condensations in gaseous nebulae. Such companions would appear as Herbig-Haro objects that are driven by strong winds of active T Tauri stars. Moreover, their relative motion with respect to their driving source can be only radial, not tangential. Thus, the locus of Herbig-Haro objects in Fig.