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Paper: Far-infrared emission lines from planetary nebulae
Volume: 73, Airborne Astronomy Symposium on the Galactic Ecosystem: From Gas to Stars to Dust
Page: 387
Authors: Dinerstein, Harriet L.; Haas, Michael R.; Erickson, Edwin F.; Werner, Michael W.
Abstract: The line trio (O III) 52, 88 microns, (N III) 57 microns has been measured in a number of planetary nebulae (PNe) and used to determine nebular properties such as density, temperature, and N/O abundance. The N/O ratios, which are elevated in many PNe due to nuclear processing in the progenitor star, agree well with optical determinations. The (O I) 63 micron line has been detected in about a dozen PNe, demonstrating the ubiquity of neutral envelopes. Measurements of (O I) 63, 146 microns and (C II) 158 microns, the primary cooling lines from the ionized/neutral interface zone or photodissociation region (PDR), have been made for six PNe. The line strengths indicate that the line-emitting regions are warm (T greater than or equal to 500 K), dense (log n greater than or equal to 4), and contain of order 0.1 solar masses.
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