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abstract
They consist of small (~0.01pc), pairs of ansae or jets located symmetrically about the nucleus and appearing near the outer edges of bright inner shells of PNs. Their velocities are highly supersonic (M~5), their ionizations are much lower, their kinematic ages are less, their N abundances are typically five times greater, and their kinetic/thermal energy desnity is much higher than the gas which surrounds them. Although one expects bow shocks to form around FLIERs, seraches for the appropriate exxcitation patterns yield negaitve results.
