The spectrum of the Seyfert galaxy NGC 3516

Journal Article · Tue Feb 15 04:00:00 EST 1977 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155017· OSTI ID:7224042

Boksenberg, A; Netzer, H

The Seyfert galaxy NGC 3516 was observed during 1975 using a digital image detector. Accurate measurements of emission-line intensities and profiles are presented. The narrow lines are emitted in a region with n/sub e/approx. =1100 cm/sup -3/. Photoionization calculations made show that excitation by a central nonthermal source can explain the observed intensity of the high-excitation forbidden lines. A cooler gas, shielded from the central ionizing source, is suggested to explain the strong (O II) and (N II) lines observed. Broad multicomponent hydrogen lines are seen in the spectrum. A decrease in the intensity of H..beta.. by 30% in 5 weeks has been observed and was associated with a large enhancement of Fe II broad lines near lambda5270 and a change of the H..cap alpha../H..beta.. line ratio. Short time continuum variations can explain the change observed in emission-line intensities, provided the atmosphere is optically thick to Balmer line radiation.

• Research Organization: Department of Physics and Astronomy, University College London
• OSTI ID: 7224042
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 212:1; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BALMER LINES
COSMIC RADIO SOURCES
ELECTRON DENSITY
EMISSION SPECTRA
FUNCTIONS
GALAXIES
H2 REGIONS
IONIZATION
LINE WIDTHS
PHOTOIONIZATION
SEYFERT GALAXIES
SPECTRA
SPECTRAL DENSITY
SPECTRAL FUNCTIONS
VARIATIONS