Hot dust on the outskirts of the broad-line region in Fairall 9
The Seyfert galaxy Fairall 9 (F9) has been observed in the far-UV and optical range with the IUE, and at 27 different epochs at J, H, K, and L. The UV continuum underwent dramatic variations, its intensity decreasing by a factor 33 from a maximum in 1978 to a deep minimum in mid-1984. The near-IR and optical fluxes changed by a factor of about three and in the same sense as the UV. The K and L emission are interpreted as thermal radiation from dust lying at about 1 lt-yr from the UV source. The Ly-alpha 1216, C IV 1550, and Mg II 2800 emission-line intensities also vary in the same sense as the UV continuum but with a lag of 155 + or - 45 days. This strongly suggests that the broad-line region (BLR) gas is photoionized and lies inside the dust shell. Strong evidence is presented that the Mg II 2800 line emissivity depends primarily on the density of soft X-ray photons, as postulated in optically thick photoionization models of the BLR. 59 references.
- Research Organization:
- International Ultraviolet Explorer Observatory, Madrid (Spain); South African Astronomical Observatory, Observatory (South Africa)
- OSTI ID:
- 6199869
- Journal Information:
- Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 337; ISSN ASJOA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
DUSTS
ELECTROMAGNETIC RADIATION
ENERGY SPECTRA
FLUIDS
GALAXIES
GALAXY NUCLEI
GASES
INFRARED RADIATION
IONIZATION
IONIZED GASES
LYMAN LINES
NEAR INFRARED RADIATION
PHOTOIONIZATION
RADIATION FLUX
RADIATIONS
SEYFERT GALAXIES
SPECTRA
ULTRAVIOLET SPECTRA
VARIATIONS