Abstract
The Galactic centre contains a low-ionization nebula that has been previously interpreted as plasma photoionized by relatively cool O stars. We consider the possibility that this material is instead ionized by more energetic continua and described by a relatively low ionization parameter (ratio of ionizing photon to nucleon density). We find that the predicted spectrum is more sensitive to ionization parameter and cloud density than to details of the ionizing continuum shape. The Galactic centre spectrum can be generated by stars with a range of temperatures irradiating clouds with multiple components of differing densities. The present calculations also show that optical emission from many LINERs (low-ionization nuclear emission-line regions) can be generated by relatively hot, yet normal O stars embedded in gas clouds similarly characterized by a range of densities.
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References
DePoy, D. L.: 1992, Astroph. J. 398, 512.
Eckart, A., et al.: 1992, Nature 355 526.
Ferland, G. J.: 1991, OSU Internal Report 91–01, Ohio State Astronomy, Columbus.
Ferland, G. J., and Netzer, H.1983, Astroph. J. 264 105.
Filippenko, A. V., and Halpern, J. P.: 1984, Astroph. J. 285, 458.
Genzel, R., and Townes, C. H.: 1987, Annual Rev. Astron. Astroph. 25 377.
Heckman, T. M.: 1980, Astro. Astroph. 87, 152.
Lacy, J. H., Townes, C. H., Geballe, T. R., and Hollenbach, D. J.: 1980, Astroph. J. 241, 132.
Phillips, M. M., Jenkins, C. R., Dopita, M. A., Sadler, E. M., and Binette, L.: 1986, Astron. J. 91, 1062.
Phinney, E. S.: 1989, in M. Morris (ed.), IAU Symposium 136, The Center of the Galaxy Kluwer, Dordrecht, p. 543.
Serabyn, E., and Lacy, J. H.: 1985, Astroph. J. 293, 445.
Terlevich, R., and Melnick, J.: 1985, Monthly Not. Roy. Astr. Soc. 213, 841.
Terlevich, R., Tenorio-Tagle, G., Franco, J., and Melnick, J. 1992, Monthly Not. Roy. Astz Soc. 255 713.
Watson, M. G., Willingale, R., Grindlay, J. E., and Hertz, P.: 1981, Astroph. J. 250, 142.
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© 1993 Springer Science+Business Media Dordrecht
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Shields, J.C. (1993). The Ionizing Radiation Field in the Galactic Centre and the Nature of Liners. In: Beckman, J.E. (eds) The Nearest Active Galaxies. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-1930-6_3
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DOI: https://doi.org/10.1007/978-94-011-1930-6_3
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-4853-8
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