Abundances of planetary nebula NGC 2392*
Kapteyn Astronomical Institute, PO Box 800, 9700 AV Groningen, The Netherlands e-mail: email@example.com
2 Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853, USA
3 NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035-1000, USA
Accepted: 10 January 2008
The spectra of the planetary nebula NGC 2392 is reanalysed using spectral measurements made in the mid-infrared with the Spitzer Space Telescope. The aim is to determine the chemical composition of this object. We also make use of IUE and ground based spectra. Abundances determined from the mid-infrared lines, which are insensitive to electron temperature, are used as the basis for the determination of the composition, which are found to differ somewhat from earlier results. The abundances found, especially the low value of helium and oxygen, indicate that the central star was originally of rather low mass. Abundances of phosphorus, iron, silicon and chlorine have been determined for the first time in this nebula. The variation of electron temperature in this nebula is very clear, reaching quite high values close to the center. The temperature of the central star is discussed in the light of the observed high stages of ionization. The nebular information indicates that the spectrum of the star deviates considerably from a blackbody.
Key words: ISM: planetary nebulae: individual: NGC 2392 / infrared: ISM
© ESO, 2008