Naslov
Luminosity Indicators in Dusty Photoionized Environments

Autori
Bottorff, Michael ; Lamothe, Joseph ; Momjian, Emmanuel ; Verner, Egerland ; Vinković, Dejan ; Ferland, Gregg

Izvornik
The Publications of the Astronomical Society of the Pacific (0004-6280) 110 (1998), 751; 1040-1045

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
H II regions; infrared: general; infrared: stars; methods: observational; planetary nebulae; stars: fundamental parameters

Sažetak
The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment and is one of the most fundamental physical quantities one can measure. We outline a method of determining the luminosity for any emission-line region using only infrared data. In dusty environments, grains compete with hydrogen in absorbing continuum radiation. Grains produce infrared emission, and hydrogen produces recombination lines. We have computed a very large variety of photoionization models, using ranges of abundances, grain mixtures, ionizing continua, densities, and ionization parameters. The conditions were appropriate for such diverse objects as H ii regions, planetary nebulae, starburst galaxies, and the narrowand broad-line regions of active nuclei. The ratio of the total thermal grain emission relative to Hb (IR/Hb) is the primary indicator of whether the cloud behaves as a classical Stro¨mgren sphere (a hydrogen-bounded nebula) or whether grains absorb most of the incident continuum (a dust-bounded nebula). We find two global limits: when , infrared recombination lines determine the source luminosity in ionizing photons ; when IR/Hb ! 100 , the grains act as a bolometer to measure the luminosity.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Informacijske i komunikacijske znanosti

POVEZANOST RADA