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Seyfert galaxies with weak broad H alpha emission lines
Abstract
Spectrophotometric measurements show five galaxies with strong narrow emission lines combined with weak, broad H-alpha and H-beta components to have line and continuum spectral properties intermediate between those of Seyfert 1 and Seyfert 2 galaxies. Because they are closer to the latter, they are called Seyfert 1.8 and Seyfert 1.9, depending on the presence of broad H-beta emissions in the scans. The observed intensity ratios of the broad H-alpha/H-beta emission lines are large compared with those of typical Seyfert 1 galaxies, suggesting the importance of dust in the broad-line regions. Narrow-line spectra of the Seyfert 1.8 and 1.9 are found to have low ionization, implying that their narrow-line region is reached by few high-energy photons. Emphasis is placed on the correlation between a strong, featureless continuum and broad H I emission lines in Seyfert and radio galaxies.
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Cited by
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Véron-Cetty, M.-P., & Véron, P. (2006) · Astronomy & Astrophysics · doi:10.1051/0004-6361:20065177 · Cited by 829
Active galactic nuclei: what’s in a name?
Padovani, P., Alexander, D. M., Assef, R. J., De Marco, B., Giommi, P., Hickox, R. C., Richards, G. T., Smolčić, V., Hatziminaoglou, E., Mainieri, V., et al. (2017) · The Astronomy and Astrophysics Review · doi:10.1007/s00159-017-0102-9 · Cited by 666
Optical Classification of Southern Warm Infrared Galaxies
Kewley, L. J., Heisler, C. A., Dopita, M. A., & Lumsden, S. (2001) · The Astrophysical Journal Supplement Series · doi:10.1086/318944 · Cited by 476
LaMassa, S. M., Cales, S., Moran, E. C., Myers, A. D., Richards, G. T., Eracleous, M., Heckman, T. M., Gallo, L., & Urry, C. M. (2015) · The Astrophysical Journal · doi:10.1088/0004-637x/800/2/144 · Cited by 451
Metadata
- Authors
- Osterbrock, D. E.
- Venue
- The Astrophysical Journal
- Publisher
- American Astronomical Society
- Published
- 1981-10
- Volume
- 249
- Pages
- 462
- ISSN
- 0004-637X (ISSN-L)
- 1538-4357
- OpenAlex
- W2041216883
- Cited by
- 306
- References
- 0
- FWCI
- 2.39
- Type
- journal article
- Language
- en
- Open access
- closed
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- Osterbrock, D. E. (1981). Seyfert galaxies with weak broad H alpha emission lines. The Astrophysical Journal. https://doi.org/10.1086/159306
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