Contributed Talk

Mixed Chemistry Phenomenon in the Galactic Bulge Planetary Nebulae

¹Ryszard Szczerba, ¹Slawomir Gorny, ²Pedro Garcia-Lario, ³anibal garcia-Hernandez (¹NCAC, Torun, Poland, ²ESAC, Madrid, Spain, ³IAC, La Laguna, Tenerife,Spain)

Out of the 26 planetary nebulae observed in the Galactic Bulge with Spitzer Space Telescope, 21 show signatures of dual-dust chemistry. Observations reveal that the simultaneous presence of oxygen and carbon-rich dust features in the infrared spectra of planetary nebulae is not restricted to late/cool [WC]-type stars. We have found that the dual-dust chemistry is seen also in all observed weak emission-line stars (wels), as well as in other planetary nebulae with central stars being neither [WC] nor wels. Most sources observed display crystalline silicate features in their spectra, with only a few PNe exhibiting, in addition, amorphous silicate bands. Three separate sub-groups of planetary-nebulae can be defined characterized by the different chemical composition of the dust and the presence of crystalline and amorphous silicates. We will show that the classification based on the dust properties is reflected in the more general properties (like gas chemical composition) of these planetary nebulae.

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