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Session 97 - Planetary Nebulae.
Display session, Thursday, January 16
We have carried out 3600 - 6800 Å\ long slit echelle spectroscopy of this bipolar nebula at the 2.1-m telescope of Observatorio Astronómico Nacional in San Pedro Mártir, Baja California, México.
The emission in the lobes is dominated by the Balmer lines; they also show emission in He I, [N II], [N I], [O III], [O II], [O I], [S III], and [S II]. In all emission lines the southern lobe emission is blueshifted while the northern one is redshifted relative to the systemic velocity, typically \DeltaV \sim 30 km/s between the bright knots separated \sim 40". The condensations appear as intensity maxima with peculiar velocities.
The core shows a faint featureless continuum and a very complex emission spectrum. In addition to those lines characteristic of PNe, it exhibits numerous relatively bright emission lines ([Fe II], [Fe III], Si II, [Fe I] and [Ni II]). These lines are also prominent in \eta Car and in RR Tel. All the lines are very wide, with a FWHM at least 50 km s^-1, some lines are as wide as FWHM \sim 100 km s^-1 (H\alpha has been reported to have extensions up to 1000 km s^-1, typical of symbiotic stars Balick 1989, AJ 97, 671). The velocity profiles of the core show different unresolved regions with large velocities that are producing the emission. The Balmer lines are double peaked with a dominating red component (H\alpha, H\beta, H\gamma, ... ), some of the high excitation forbidden lines are also double peaked with a dominating it blue component ([O III], [Ne III], ...) while others are single peaked (He I 5876, [N II] 6584, [O I] 6300) at the systemic velocity.
We derive the physical conditions and chemical compostion of the lobes and the core. We present possible kinematical models of the core emitting region.
Program listing for Thursday