Infrared emission lines from planetary nebulae

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5323315

Shure, M A

Ionic abundances and electron temperatures in the central regions of a number of planetary nebulae were determined using infrared fine-structure lines in the 15 to 40 ..mu..m range. The 91 cm telescope of the NASA Kuiper Airborne Observatory was used to measure the following lines: (S III) 18.71 ..mu..m, (Ar III) 21.83 ..mu..m, (Ne V) 24.28 ..mu..m, (O IV) 25.87 ..mu..m, (S III) 33.47 ..mu..m and (Ne III) 36.02 ..mu..m. Line emission was integrated over the entire emitting region in a total of 22 planetary nebulae, ranging from medium to high excitation. All except the (Ar III) line were detected at greater than 3sigma. Although optical emission lines have been used for decades to derive both abundances and temperatures, use of the infrared lines offer two distinct advantages over the optical lines: (1) infrared line emission is insensitive to temperature, and (2) the high excitation ions O IV and Ne V probe regions closer to the central star than do the bright optical lines. As a consequence of (1), abundances derived from the infrared lines do not require accurate temperatures for nebulae, in contrast to the case for temperature-sensitive optical lines. Infrared ionic abundances are therefore potentially much more accurate than the optical abundances. By comparing integrated radio free-free emission to the infrared line fluxes, abundances were determined for 19 nebulae.

• Research Organization: Cornell Univ., Ithaca, NY (USA)
• OSTI ID: 5323315
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABUNDANCE
ACCURACY
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
ELECTRON TEMPERATURE
FINE STRUCTURE
INFRARED SPECTRA
IONS
NEBULAE
PLANETARY NEBULAE
SPECTRA
VISIBLE SPECTRA