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C. Sánchez Contreras (JPL/Caltech), A. Castro-Carrizo (National Astronomical Observatory of Spain, OAN), R. Sahai (JPL/Caltech), V. Bujarrabal (OAN), L.F. Miranda (IAA, Spain), J. Alcolea (OAN)
We have studied the structure and kinematics of the high- and low-excitation circumstellar material in two protoplanetary nebulae (i.e. objects rapidly evolving from the AGB to the planetary nebula stage): CRL618 and M2-56.
The high-excitation component (atomic and ionized gas typically at ~10,000-20,000K) is traced by many recombination and forbidden emission lines in the visible. Optical long-slit spectra were obtained with the Intermediate Dispersion Spectrograph mounted on the 2.5m Isaac Newton Telescope (La Palma Island, Spain). We used 1''-wide slits located at different positions and orientations on the nebula to obtain ~~50-80km~s-1 resolution spectra in the ~[6233-6806]Å\ and ~[4558-5331]Å\ ranges. The low-excitation component (cool molecular gas) has been studied by means of interferometric (~1'' resolution) observations of the emission from different molecular species in the millimeter-wavelength range (we observed the high density tracers HCO+(1-0) and HCN(1-0) in CRL618 and CO(2-1 & 1-0) in M2-56). Observations were performed using the Owens Valley and the IRAM radio interferometers (respectively located at California, USA, and Plateau de Bure, France).
We have modeled our multiwavelength data to obtain the three dimensional structure and kinematics of both circumstellar components in these two objects. We present the results from our modelling and discuss about the origin and evolution of the different components within the two-winds interaction scenario.
This work is partially funded through a NASA LTSA grant to R.S. and by the Spanish DGES project PB96-0104.