Bibcode
                                    
                            Manchado, A.; Pottasch, S. R.
    Referencia bibliográfica
                                    Astronomy and Astrophysics (ISSN 0004-6361), vol. 222, no. 1-2, Sept. 1989, p. 219-226.
Fecha de publicación:
    
                        9
            
                        1989
            
  Número de citas
                                    40
                            Número de citas referidas
                                    34
                            Descripción
                                    Spatial resolved low resolution spectroscopy of the haloes around the
planetary nebulae NGC 6543 and NGC 6826 were conducted. The results
imply that the radiation is thermal and not due to dust reflection. From
those data chemical abundances and masses were calculated. Chemical
abundances decrease in the haloes, while masses increase up to ten times
in NGC 6543 reaching a value of 1 solar mass. The mass loss required to
form these haloes coincides with that expected at the beginning of the
evolution off the AGB.