4 The bipolar jets and blobby mass outflow

Figure 2 presents the temporal evolution of HeI 5876 Å emission line profile as a template for other helium lines, H$\alpha$ for hydrogen, and [OIII] for the nebular lines. Over the observational period no other substantial change affected the spectrum of StH$\alpha$ 190.

The H$\alpha$ profile is dominated by a central component that has remained remarkably constant over the last four mounts (see Table 1). Two weaker and symmetrically placed components are flanking the central component. They show large day-to-day variability in both $RV_\odot$ and width (cf. Table 1). We identify them as spectral signatures of jet-like discrete ejection events. Weak P-Cyg absorptions interfere with the blue jet component, reducing its width and its velocity shift vs. the main H$\alpha$component. Orbital inclination of StH$\alpha$ 190 is probably high, so the de-projected velocity of the jet components must be much larger than the observed velocity shifts ($\sim$150 km s^-1) and well in excess of the escape velocity from the O sub-dwarf companion to the G7 III ($\sim$1000 km s^-1). The mass of the gas originating the jets is $10^{-11}~M_\odot$, while the circumstellar ionized region has $M = 1~10^{-6} \ M_\odot$ and $R = 4.5~10^{14}~{\rm cm} = 30$ AU (assuming a simple spherically symmetric geometry). The mass loss rate necessary to sustain the jets is $\dot{M} \sim 5\ 10^{-8}\ (V_{\rm jet}/1000\ {\rm km~s^{-1}})~M_\odot\ {\rm yr}^{-1}$.

The jet components are visible in the profiles of HeI lines too (see HeI 5876 Å in Fig. 2). The velocity and profile of the red component corresponds closely to that seen in the H$\alpha$ profile. The most outstanding feature of the HeI profile is however the multi-component and highly variable P-Cyg component, with terminal velocity even in excess of 300 km s^-1. The P-Cyg absorption can be so strong as to completely overwhelm the jet's blue component. The P-Cyg profiles evolve on a few days or hours time scale. The strong P-Cyg component on Sep. 9 (see Fig. 2), for example, accelerated outward by 20 km s^-1 day^-1 and dissolved in the next two days, while being replaced by a growing and accelerating new P-Cyg component. The typical mass involved in the absorption profiles is $M = 10^{-11}{-}10^{-10}~M_\odot$.

The relative appearance of hydrogen and HeI lines in StH$\alpha$ 190 closely resembles Hen 3-1341 and its well developed jets and mass outflow (Tomov et al. 2000). We are continuing with the photometric and spectroscopic monitoring and a detailed modeling of StH$\alpha$ 190 will be presented elsewhere.