Bibcode
                                    
                            Phillips, J. P.; Riera, A.; Mampaso, A.
    Bibliographical reference
                                    Astronomy and Astrophysics (ISSN 0004-6361), vol. 234, no. 1-2, Aug. 1990, p. 454-468.
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                        8
            
                        1990
            
  Citations
                                    10
                            Refereed citations
                                    10
                            Description
                                    Deep spectra of the planetary nebula IC 418 were obtained in the
wavelength range 4190-5850 A. The data made it possible to map an
extended halo about the source, evaluate the variation in halo intensity
with radius, and model the results in terms of a radially symmetric dust
scatter envelope. It is suggested that the nebula is in a relatively
early stage of evolutionary expansion, with a lifetime of no more than
about 850 yrs. It is also believed that the enveloping halo zone
represents an earlier mass-ejection phase in the low-mass carbon star
progenitor.