| Description |
Carbon (and nitrogen) abundances, which can be used to constrain
stellar evolution theory, are not well known in Galactic bulge
planetary nebulae because the lines used are in the ultraviolet and
are weak and difficult to measure accurately. We propose to measure
the C(+) abundance in a selection of low ionization PNe where it is
the dominant ion, by measuring the CII line at 157 microns. The
nitrogen line at 122 microns is used in conjunction with the line at
6584 angstroms to accurately determine the electron temperature, which
not only will make the nitrogen abundance more accurate, but will
enable abundances to be determined for other ions measured in the
visual spectrum. |
