2006ApJ...650..985W

We present an observational picture of the HH 409 bipolar outflow including the detection of six previously unreported Herbig-Haro knots from the Herbig Ae star HD 163296. This study combines seven years of data from ground-based Fabry-Pérot and HST coronagraphic imagery, as well as HST long-slit spectral imagery. The redshifted counterjet includes a chain of six Herbig-Haro knots spanning >27" to the northeast (P.A.~42°) of the source and has been active for >80 yr. The brightest knot in the counterjet is HH 409 C, a low-excitation bow shock with a shock velocity V_s∼50 km/s and total space motion V_jet~260 km/s. The presence of additional knots in the counterjet beyond the bow shock may indicate precession of the jet axis. The blueshifted jet includes two closely spaced knots within 10" and a distant bow shock (~21") southwest (P.A.~223°) of the source. The brightest knot in the jet is HH 409 A, a higher excitation more bullet-like shock with V_s∼90 km/s and V_jet~360 km/s. The average opening angles for both the jet and counterjet are similar, α_a∼2°, and consistent with opening angles of lower mass T Tauri stars. The mass-loss rates in both lobes of the flow, despite the asymmetry of the knots, are also comparable, M{dot}_out∼1.0x10^–8 M_☉/yr. This suggests that variations in the mass outflow rate are not more than a factor of ∼2.